Progress 10/01/08 to 09/30/10
Outputs
OUTPUTS: The most notable accomplishment in 2010 was development and hosting a Soybean Aphid Summit in Minneapolis, MN on July 28-30, 2010. The program was developed in conjunction with the North Central Soybean Research Program (NCSRP), a grower based multi-state check off program. Twelve soybean aphid researchers representing the 12 states in the North Central region with an active soybean aphid program were represented. Approximately 50 Farmer-leaders and staff from various state soybean commodity boards were present. The purpose of the Soybean Aphid Summit was to review research and outreach accomplishments to date, listen to concerns expressed by the grower representatives that led to a discussion of the overall research direction for the future. Topics included were the management strategies for soybean aphid with a focus on economic threshold, host plant resistance, and current control recommendations. A separate panel of experts led a discussion on the state of host plant resistance. Topics included modification of economic thresholds of aphids on resistant varieties, and included the impact of soybean aphid biotypes on deployment of Rag (Resistance Aphis glycines) genes, and the educational needs to inform growers how to deploy aphid resistant varieties in 2011. The future of exploring for novel genes and the importance of genetic resistance as a key component of soybean aphid management was highlighted. The last topic was deployment of classical biological control for permanent reduction of soybean aphid density in the North Central region. Plans were discussed on how best to get the information to growers and perhaps another multi-page color insert into a trade magazine might be needed to assist growers in selecting and using aphid-resistant soybean varieties. A series of articles in the new online journal, Journal of Integrated Pest Management, sponsored by the Entomological Society of America will launch in January 2011 and several articles focused on soybean aphid will be included in this inaugural issue. These articles are focused for the extension specialist and consultant and professional agronomist and outline the current state of knowledge with regard to management in this case of soybean aphid. PARTICIPANTS: Individuals: Heimpel, G.E. (co-PI) Potter, B. (co-PI) MacRae, I.V. (co-PI) Hutchison, W.D. (collaborator) Moon, R.D. (collaborator) McCornack, B.D. (graduate student, co-PI) Costamagna, A. (post-doc) Hodgson, E.W. (graduate student, co-PI) Koch, K. (graduate student) Heidel, T. (graduate student) Partner organizations North Central Soybean Research Program (NCSRP) Minnesota Soybean Research & Promotion Council (MNSR&PC) TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The initial discovery of soybean aphid in Minnesota followed the report of aphids on soybean in Wisconsin in July 2000. By the end of that growing season soybean aphid had been identified in 10 contiguous Midwestern states. Minnesota led the initial work on developing an economic threshold for soybean aphid which resulted in a landmark publication in the Journal of Economic Entomology that represented the equivalent of 2 decades of research (19 location-years conducted during 3 growing seasons). This economic threshold and the adoption of this threshold by producers throughout the upper Midwest will save soybean producers $1.3 billion over the next 15 years (estimated by Michigan State Ag Economist). Equally important, was the development of a simple method to sample soybean aphids, known as "Speed Scouting," which accelerated adoption of IPM for soybean aphid. Before the arrival of the soybean aphid, soybean producers in Northern Great Plains rarely applied insecticide or miticides. Typically, less than 1% of the soybean acres in the North Central region were treated with an insecticide, but after 2000 when soybean aphid became established, outbreaks of the aphid have occurred on a regional scale with populations often reaching several thousand individuals per plant, capable of reducing yields by 40%. In outbreak years, insecticide use could exceed 50% of the planted acres in a given state. With more than 62 million acres of soybean annually produced in the North Central US, preventing yield loss from aphids on even a tenth of these acres would represent annual savings of more than $694M (6.2M*40%*40bu/a*$7/bu). One reason the thresholds have been so widely adopted (80% adoption estimated by Olson and Badibanga, U of MN Applied Economics Dept.) was because of the general awareness of soybean aphid biology and management by the grower community. The North Central Soybean Research Program (NCSRP) funded a 16-page color brochure using data and photographs supplied by soybean researchers across the Midwest, including Minnesota. This brochure was provided as an insert to the American Soybean Association trade magazine in winter 2004 which meant that nearly every soybean producer in the U.S. received a copy of the latest information on soybean aphid biology and management. A second brochure highlighting the classical biological control of soybean aphid has increase awareness of growers of the importance of natural enemies to the overall management of the soybean aphid. The other major accomplishment was assisting breeders (both public and private) in identifying resistant germplasm for incorporation into aphid-resistant varieties. Aphid-resistant varieties were first available in limited supply to growers in 2010 and will be widely planted in 2011. Overall, the project developed a fully integrated pest management program with a solid foundation in aphid biology, development of sampling schemes, economic thresholds, deployment of aphid resistant varieties, and the long term goal of suppressing soybean aphid reproduction using classical biological control.
Publications
- Ragsdale, D. W., G. E. Heimpel, D.A. Landis, J. Brodeur, N. Desneux. 2011. Ecology and Management of the soybean aphid in North America. Annual Review of Entomology. 56: 375-399.
- Pang, Y.P., S. Brimijoin, D. W. Ragsdale, K. Y. Zhu, and R. Suranyi. 2011. Novel and Viable Acetylcholinesterase Target Site for Developing Effective and Environmentally Safe Insecticides, Current Drug Targets. accepted for publication in 2011.
- Polsinelli, G. A., S. K. Singh, R. K. Mishra, R. Suranyi, D. W. Ragsdale, Y. P. Pang, and S. Brimijoin. 2010. Insect-Specific Irreversible Inhibitors of Acetylcholinesterase in Pests Including the Bed Bug, the Eastern Yellowjacket, German and American Cockroaches, and the Confused Flour Beetle. Chem. Biol. Interact. 187 (1-3): 142-147.
- ONeal, M., K. Johnson, E. Hodgson, D. Ragsdale, I. MacRae, B. Potter, C. DiFonzo, K. Tilmon, E. Cullen, P. Glogoza, and B. P. McCornack. 2010. Comment on "Soybean Aphid Population Dynamics, Soybean Yield Loss, and Development of Stage-Specific Economic Injury Levels" by M. A. Catangui, E. A. Beckendorf, and W. E. Riedell, Agron. J. 101:1080-1092 (2009). Agronomy Journal 102: 55-56.
- Alejandro, A.C., McCornack, B. P., D. W. Ragsdale, and. D.A. Landis. 2010. Development and Validation of Node-Based Sample Units for Estimating Soybean Aphid (Hemiptera: Aphididae) Densities in Field Cage Experiments. J. Econ. Entomol. 103: 1483-1492.
- Koch, K.A., B. D. Potter, and D. W. Ragsdale. 2010. Non-target Impacts of Soybean Rust Fungicides on the Fungal Entomopathogens of Soybean Aphid. J. Invert. Pathology 103: 156-164.
- Chiozza, M.V., M.E. ONeal, G.C. MacIntosh, D.I. Chandrasena, N.A. Tinsley, S.R. Cianzio, A.C. Costamagna, E. Cullen, C.D. DiFonzo, B.D. Potter, D.W. Ragsdale, K. Steffey, K.J. Tilmon, and K.J. Koehler. 2010. Host plant resistance for soybean aphid management: a multi-environment study. Crop Sci. (Accepted)
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Aphids are vectors of multiple plant viruses and can cause crop injury through feeding injury alone. Effective virus management is achieved through both vector control and host plant resistance. The goal of this research project is to focus on aphid management and how this management might impact spread of plant viruses. Evaluation of breeding lines that are resistant to the aphid, viruses or to both aphids and viruses is also a focused goal. This project focuses on two distinct cropping systems, seed potato and soybean. In seed potato production the health of the mother plant dictates the health of the daughter tubers. Since potatoes are planted from vegetative tubers and not true seed, many plant viruses become reintroduced into the system through the sale and planting of virus-infected seed potatoes (tubers). We continually work with seed potato producers through commodity organizations to communicate the most effective management strategies to control aphid populations while at the same time minimize the impact of aphid-transmitted plant pathogens. Our work is disseminated directly to growers through on-farm demonstrations, meetings held during the winter and through publication of results in appropriate journals for peer scientists to use in their educational programming. Work with the soybean production system is focused primarily on the feeding damage of the aphid itself. Aphids can cause up to a 40% loss in yield if left uncontrolled and our goal here is to develop the tools that growers can use to prevent catastrophic losses to aphids in the northern Great Plains where 85% of the soybean production in the US is located. Communication of results is through meetings with producers and their consultants, the use of mass media (radio, internet, and print), and through scholarly publications focused at our peers. PARTICIPANTS: Professor David Ragsdale was the lead scientist on the soybean aphid project. The soybean aphid project collaborates broadly with faculty throughout the upper Midwest. The research focusing on potato production is lead by Professor Ian MacRae and former Professor (now retired) Dr. Edward B. Radcliffe. Drs. MacRae and Ragsdale are coadvising an M.S. student, Ms. Caitlin Krueger who is working in the seed potato production system. TARGET AUDIENCES: Potato producers and their respective commodity associations in Minnesota and North Dakota are the target of the potato cropping system research. The soybean aphid project works collaboratively with scientists, producers and their commodity organizations throughout the upper Midwest and in particular, the North Central Soybean Research Program and the Minnesota Soybean Research and Promotion Council who sponsored much of the research to date on soybean aphid. We regularly report to these commodity organizations. Other target audiences are peers throughout North America who are dealing with the invasive soybean aphid. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
A major impact of this research has been the widespread adoption by seed potato producers of targeted insecticide treatment of green peach aphids at field edges where our research documented this is where migrating aphids alight and begin their whole field colonization. We have further refined this research to demonstrate that removing infected plants in a seed potato field mechanically, a process known as roguing, leaves sufficient gaps in the field that aphids recognize as an edge and can thus colonize the interior of the field if a sufficient number of these gaps occur. By targeting insecticide treatment for aphids at field edges upon initial field colonization we documented that was no significant difference in aphid suppression or any increase in virus levels in post-harvest tests between edge treated or whole-field treated seed potato fields. By confining aphid insecticidal treatment to field edges, producers significantly reduce negative outcomes associated with whole field application and growers benefit by reducing overall control costs. A similar program was evaluated for control of soybean aphid, but was found not to be effective. Thus soybean producers cannot treat just field edges and achieve satisfactory aphid control. In soybean we have successfully developed an economic threshold of 250 aphids per plant as a point in the population growth of soybean aphids to trigger action by growers to chemically manage the population. Treatment below the 250 threshold often results in the need to re-treat field while waiting until populations exceed 250 often will result in loss of yield. The economic injury level is defined as the density of aphids that causes yield loss equal to the cost of control is 674 aphids per plant. The ET and EIL numbers are widely adopted throughout the northern Great Plains as the appropriate treatment levels for this new invasive aphid pest of soybean. Host plant resistance to aphids continues to be evaluated. In potato we have identified a breeding line that has sufficient aphid and plant virus resistance to be of value for plant breeders to use this parental line as a source of aphid and virus resistance. The line HPR24 was provided to potato breeders for their use. In soybean we have helped to evaluate multiple lines of resistance to soybean aphid by collaborating broadly with soybean breeders at Universities and at seed companies. 2010 marks the first year when soybean aphid resistant soybean varieties will be commercially available. Aphid population growth on these resistant lines is much lower than corresponding growth on lines lacking the aphid resistance genes (Rag1, Rag2, Rag3 and Rag4). We are developing economic thresholds for use with these resistant lines and are collaborating with entomologists, plant breeders, and company agronomists across the region to evaluate this research methodology.
Publications
- Yuan-Ping Pang, Fredrik Ekstrom, Gregory A. Polsinelli, Yang Gao, Sandeep Rana, Duy H. Hua, Bjorn Andersson, Per Ola Andersson, Lei Peng, Sanjay K. Singh, Rajesh K. Mishra, Kun Yan Zhu, Ann M. Fallon, David W. Ragsdale, Stephen Brimijoin. 2009. Selective and Irreversible Inhibitors of Mosquito Acetylcholinesterases for Controlling Malaria and Other Mosquito-Borne Diseases. PloS ONE 4 (2), e4349 (2009).
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Activities included on this project are demonstration sites and field days conducted in conjunction with the applied research and reporting those results through extension education activities (field days, short courses, workshops and scientific symposia) held throughout the year. For example: Research findings were presented to 17 unique audiences ranging in size from 650 to a few dozen in 8 different states during 2008. In addition to these public presentations, I was invited to make similar presentation to scientific staff of 3 private companies or foundations (Monsanto Corp. - St. Louis, MO, Syngenta Crop Protection, Lucerne, Switzerland, and the Gates Foundation for operations in Africa. The focus of these presentations were on the economic impact of an invasive species in North America, the soybean aphid, and its impact and management tools we have developed so that US soybean producers remain profitable while trying to deal with this new and invasive insect pest of soybean. Products made available to producers in the form of decision analysis trees which will be made available as a modified Soybean Aphid Growth Estimator (SAGE) model for producers to access and use via the WWW. In addition these tools will be used to train undergraduate students enrolled in a Crop and Pest Management course (CFANS 3005) for students enrolled in various agricultural sciences at the University of Minnesota. Dissemination of 12 page color brochure produced in partnership with the North Central Soybean Research Program (NCSRP) was provided to every soybean producer in the North Central US. The brochure described the ongoing research activity on soybean aphid biological control where the goal is to reuniting soybean aphid parasitoids from China with soybean aphid in the US. This Soybean Aphid Research Update is available for downloading at: http://www.planthealth.info/pdf_docs/sba_update08.pdf. PARTICIPANTS: Three post-doctoral scientists and 1 Ph.D. student worked on the projects during the past year, Dr. Brian McCornack (now at Kansas State University) and Dr. Alejandro Costamagna (now with CSIRO, Brisbane Australia) and Ms. Karrie Koch and 6 undergraduate research assistant all labored on the soybean aphid projects in 2008. In potato research Dr. Jeff Davis (now at Louisiana State University) was a principal investigator on the projects involving potato pest management. Collaborators include entomologists from several adjoining states who are involved in a commodity funded project on soybean aphid. The North Central Soybean Research Program (NCSRP) provided key financial support for work on soybean aphid management and biological control. The program director is Dr. David Wright, Director of Research, North Central Soybean Research Program, Telephone: (800) 383-1423, email: dwright@iasoybeans.com. Biological Control of soybean aphid involves two insect quarantine facilities, one operated by USDA in the Newark, DE location by Drs. Kim Hoelmer and Keith Hopper (khopper@udel.edu and khoelmer@udel.edu) and a Biosafety Level 2 quarantine laboratory operated by the Minnesota Department of Agriculture, Dr. Zhishan Wu, Quarantine Officer, State of Minnesota, Address: University of Minnesota, MAES/MDA Plant Growth Facilities East Room 102, 1907 Dudley Ave., St. Paul, MN 55108 Tel: (612) 625-3779 (office), (612) 626-3568 (facility) Fax: (612) 626-6411 Email: Zhishan.Wu@state.mn.us Collaboration with private companies (Monsanto Corp., St. Louis, MO and Syngenta Crop Protection) provided financial support for testing crop protection chemicals and screening soybean germplasm for aphid resistance. TARGET AUDIENCES: The target audience for this research includes all soybean producers in the North Central US and their advisors (Certified Crop Advisors) who seek training through a variety of forums (field days, summer field tours, intensive crop pest management short courses and seminars, and consulting arrangements with private companies). All of these individuals are involved in making pest management decisions or influencing staff who make those decisions. We also trained cooperative extension educators (State specialists and county based staff) in proper aphid pest management methods. An economic analysis of our soybean aphid management recommendations by Agricultural Economists at Michigan State showed the future value of the soybean aphid economic threshold of 250 aphids per plant to be $1.3 billion (forward projected 15 years into the future). PROJECT MODIFICATIONS: There has been a shift in emphasis in this project from one focused almost solely on potato pest management where aphids and the plant viruses they transmit (vector) were the target insect vector and virus pathosystem to one that focuses on soybean aphid a more important invasive aphid species that can cause significant economic loss over a wide area of soybean production in Minnesota (nearly 7 million acres are grown annually). Soybean aphid is also a virus vector but those relationships are far less important than the yield loss attributed to soybean aphid feeding that can translate into yield losses approaching 50% if left untreated.
Impacts
Outcomes of the research conducted has been to document the value of natural enemies in controlling aphids and that when natural enemies are eliminated that aphid reproduction can rapidly cause significant loss in crop production. In soybean aphid we have shown that the 250 aphids per plant economic threshold is broadly applicable to soybean production in the North Central region. Regardless of variety, row spacing, or maturity group, the economic threshold will allow producers 1 week to arrange for treatment of the field to prevent economic loss, defined as loss (in bu/ac) equal to the cost of control. Pesticide manufacturers have often insisted that given the current commodity prices that the economic threshold must be lower, but our research showed this is not the case and we demonstrated what can occur of treatment occurs too early (aphid population resurgence due to lack of natural enemies).
Publications
- ABSTRACTS - Katovich, E.J.S., R. L. Becker, L.C. Skinner, and D.W. Ragsdale. 2008. Growth and phenology of three Lythraceae species in relation to feeding by the leaf beetles Galerucella spp. XII International Symposium on Biological Control of Weeds, Le Grande Motte, France, April 2007. CAB International, pp. 358.
- Skinner, L.C., D. W. Ragsdale. 2008. Population dynamics and long-term effects of Galerucella spp. on purple loosestrife, Lythrum salicaria, and non-target native plant communities in Minnesota. International Symposium on Biological Control of Weeds, Le Grande Motte, France, April 2007. CAB International, pp. 643.
- Becker, R.L., D.W. Ragsdale, D. Sreenivasam, J. Heil, Z. Wu, M. Hanks, E.J.S. Katovich, and L.C. Skinner. 2008. The new quarantine facility, St. Paul, MN USA. International Symposium on Biological Control of Weeds, Le Grande Motte, France, April 2007. CAB International, pp. 395.
- REFEREED JOURNAL ARTICLES - Davis, J.A., E. B. Radcliffe, C. A. Thill, and D. W. Ragsdale. 2008. Planter skips and impaired stand favors PVY spread in potato. Amer. J. Potato Research (accepted, Oct 2008, in press)
- Yoder, M. V., L.C. Skinner, and D.W. Ragsdale. 2008. Common buckthorn, Rhamnus cathartica L.: Available feeding niches and the importance of controlling this invasive woody perennial in North America. Proc. International Biological Control of Weeds Symposium. pp. 232-237.
- Carroll, M. W., E. B. Radcliffe, I. V. MacRae, D. W. Ragsdale, K. D. Olson, and T., Badibanga. 2008. Border Treatment to Reduce Insecticide Use in Seed Potato Production: Biological, Economic, and Managerial Analysis. Amer. J. Potato Res. (accepted April 2008, in press)
- Katovich E.J.S., R.L. Becker, D.W. Ragsdale, and L.C. Skinner. 2008. Growth and Phenology of Three Lythraceae Species in Relation to Feeding by Galerucella calmariensis and Galerucella pusilla: Predicting Ecological Host Range from Laboratory Host Range Testing. Inv. Plant Sci Management. 1(2):207-215.
- McCornack, B. P., A. D. Costamagna, and D. W. Ragsdale. 2008. Within-Plant Distribution of Soybean Aphid (Hemiptera: Aphididae) and Development of Node-Based Sample Units for Estimating Whole-Plant Densities in Soybean. J. Econ. Entomol. 101(4): 1501-1509.
- BOOK CHAPTERS - Radcliffe, E. B., D. W. Ragsdale, R. A. Suranyi, C. D. DiFonzo, and E. E. Hladilek. 2008. Aphid Alert: how it came to be, what it achieved, and why it proved unsustainable. In Areawide IPM: Theory to Implementation, Koul, O., G. W. Cuperus, and N.C. Elliott [eds.]. pp. 244-260. CAB International , Wallingford.
- Radcliffe, E. B., D. W. Ragsdale, and R. A. Suranyi. 2008. IPM Case Studies: Seed Potato. In: Aphids as crop pests, H.F. van Emden and R. Harrington (eds.). CAB International, 717 pp.
- Davis, J. A., E. B. Radcliffe, W. Schrage and D. W. Ragsdale. 2008. Seed potato production IPM, In: E.B. Radcliffe, W. D. Hutchison, and R. E. Cancelado (eds.), Insect Pest Management, Cambridge University Press.
- REFEREED PROCEEDINGS - Ragsdale, David W. and Karrie A. Koch. 2008. Fungicides: Do They Adversely Affect Beneficial Insect Pathogens in Multiple Cropping Systems Proceedings of the 2008 Illinois Crop Protection Technology Conference, pp. 57-66. http://www.ipm.uiuc.edu/education/proceedings/icptcp2008.pdf
- Ragsdale, David W. and Karrie A. Koch. 2008. Fungicides: Do They Adversely Affect Beneficial Insect Pathogens in Multiple Cropping Systems Proceedings of the 2008 Illinois Crop Protection Technology Conference, pp. 57-66.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Dissemination of research outputs have been made to a variety of audiences including 7 grower organizations (Northern Plains Potato Growers, MN Area II Potato Growers, MN Soybean Growers Association, North Central Soybean Research Program, Minnesota Agri Growth Council, and Montreal Soybean Producers Association, Minnesota ), 3 presentations at key extension meetings in Minnesota (Crop Pest Management short course, Crop Professional Field School), multiple legislative delegations mostly focused on the the research involved in out biosafety level 2 and 3 quarantine facility on the St. Paul campus (US Congress, MN State Legislature), and 2 formal meetings of University scientists with the Ag Chem industry (Bayer and Monsanto), and 11 presentation were made to peers at scientific meetings (Entomological Soc. of Amer., Potato Assoc. of Amer., USDA Multistate research committees, S1010 and WERA89).
PARTICIPANTS: David W. Ragsdale, Professor of Entomology, University of Minnesota Brian P. McCornack, Research Associate, Dept. of Entomology, University of Minnesota Karrie A. Koch, Graduate Research Assistant, Dept. of Entomology, University of Minnesota Alejandro Costamagna, Research Associate, Dept. of Entomology, University of Minnesota Jeffrey A. Davis, Research Associate, Dept. of Entomology, University of Minnesota Elizabeth J. Katovich, Research Associate, Dept. of Agronomy and Plant Genetics, University of Minnesota
TARGET AUDIENCES: Minnesota Department of Agiculture, Seed Certification Program Minnesota Department of Natural Resources - staff in invasive species program Minnesota Soybean Producers Minnesota Potato Producers
Impacts
An economic analysis of the damage of soybean aphid in terms of current market conditions and control costs were presented to all soybean focused meetings in Minnesota, the region (North Central Region) and in Quebec. This new invasive insect (soybean aphid) has caused more than $1 billion in losses since it was first discovered in the year 2000 and regional research directed in Minnesota has been the basis of the economic threshold adopted by all states and provinces in Canada. By using the economic threshold we can demonstrate to producers that only when aphids reach 250 aphids per plant and the population is continuing to grow is it beneficial to apply an insecticide. Aphid densities that remain low can be tolerated and cause no economic loss thus preventing the overuse of insecticide in soybean.
Publications
- Ragsdale, D. W., B. P. McCornack, R. C. Venette, B. D. Potter, I. V. MacRae, E. W. Hodgson, M. E. ONeal, K. D. Johnson, R. J. ONeil, C. D. Difonzo, T. E. Hunt, P. Glogoza, and E. M. Cullen. 2007. Economic threshold for soybean aphid (Homoptera: Aphididae). J. Econ. Entomol. 100(4): 1258-1267.
- Davis, J.A., E. B. Radcliffe, and D. W. Ragsdale. 2007. Identifying and mapping resistance to green peach aphid, Myzus persicae (Sulzer), in potato. Am. J. Potato Res. 84: 86-87.
- Radcliffe, E. B., D. W. Ragsdale, R. A. Suranyi, C. D. DiFonzo, and E. E. Hladilek. 2007. Aphid Alert: how it came to be, what it achieved, and why it proved unsustainable. In Areawide IPM: Theory to Implementation, Koul, O., G. W. Cuperus, and N.C. Elliott [eds.]. CAB International. (in press)
- McCornack, B. P., R. L. Koch, and D. W. Ragsdale. 2007. A simple method for in-field sex determination of the multicolored Asian lady beetle (Coleoptera: Coccinellidae). J. Insect Science. 7: 10 http://www.insectscience.org/7.10/i1536-2442-2007-10.pdf
- Hodgson, E. W., B. P. McCornack, K. A. Koch, D. W. Ragsdale, K. D. Johnson, M. E. ONeal, E. M. Cullen, H. J. Kraiss, C. D. DiFonzo, M. Jewett, and L. M. Behnken. 2007. Field validation of Speed Scouting for soybean aphid. Online Journal. Crop Manag. http://www.plantmanagementnetwork.org/cm/
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Progress 01/01/06 to 12/31/06
Outputs
Potato, Solanum tuberosum L., is planted using vegetative tubers thus aphid-transmitted viruses are extremely important since seed tubers are only as healthy as the mother plant from which they are derived. For successful production, commercial potato producers must plant high quality, disease-free tubers. Planting virus infected tubers reduces yield and quality of the crop, at times resulting in complete failure of the crop to be marketed. The two most important potato viruses are Potato leafroll virus (PLRV, Genus Polerovirus, Family Luteoviridae) and Potato virus Y (PVY, Genus Potyvirus, Family Potyviridae). These viruses are both transmitted by aphids, but their transmission characteristics dictate that each control measures are different for each virus. We have shown that to reduce spread of PLRV only field borders need to be treated with an insecticide. This takes advantage of the behavior of the green peach aphid which colonizes the edge of fields first.
Prediction of movement of green peach aphid can be forecasted using the frequency and duration of low level jet winds with their origin in the southern U.S. For PVY control we have promoted the use of a border crop that takes advantage of aphid landing behavior. However, since 1992, a PVY epidemic has devastated the seed potato industry and this ongoing epidemic is fueled, in part, by a change in virus strains. The ordinary or common strain designated as PVYO has been largely replace with PVY strains that are less symptomatic in potato, designated as PVYN or as a recombinant strain or mixture of the two strains designated as PVYN:O. We have worked with the seed certification agency in Minnesota to independently assess their winter test procedures. Using a serological test, ELISA we showed that plants visually scored as PVY positive agreed with ELISA 87% of the time three years ago. In the second year, this agreement between visual and ELISA dropped to 62% and by the third year, there
was only a 50% agreement. Over the same period, PVYO became less common (46% to 21%) so that by the third year, PVYN was the more common strain, 79%. Our research shows that the seed potato certification procedures must either use a serological test to conduct winter testing or reduce the number of field generations that a seed lot can be grown from the current 5 to no more than 3 if field generations. The most critical component of seed potato IPM is a seed certification program that effectively reduces inoculum. The other tactics are only effective in reducing the level of inoculum entering the field from outside sources. But cultural control tactics that take advantage of vector behaviour must work in concert with an effective seed certification program that reduces inoculum.
Impacts
Crop borders, mineral oil sprays and other non-chemical control tactics are no longer effective if the source of PVY inoculum is the seed potato crop itself. Seed certification agencies must either no longer rely on visual inspection as a means of certifying a seed potato crop as virus-free. Either the seed potato crop must be grown for fewer field generations following tissue culture propagation of virus-free plants or the agencies must adopt more rigorous testing methods to certify a seed potato crop.
Publications
- Davis, Jeffrey A., Edward B. Radcliffe and David W. Ragsdale. 2006. Resistance to green peach aphid, Myzus persicae (Sulzer), and potato aphid, Macrosiphum euphorbiae (Thomas), in potato cultivars. Amer. J. Pot. Res. In press.
- Davis, J. A., E. B. Radcliffe, and D. W. Ragsdale. 2006. Modeling effects of high and fluctuating temperatures on green peach aphid, Myzus persicae (Hemiptera: Aphididae). Environ. Entomol. 35: 1461-1468.
- Zhu, M., E.B. Radcliffe, D.W. Ragsdale, I.V. MacRae and M.W. Seeley. 2006. Low-level jet streams associated with spring aphid migration and current season spread of potato viruses in the U.S. northern Great Plains. Agricultural Forest Meteorol. 138: 192-202.
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Progress 01/01/05 to 12/31/05
Outputs
Potato virus Y (PVY) and Potato leafroll virus (PLRV) are two important aphid-transmitted viruses in potato. Because insecticides cannot prevent PVY spread, we have been selecting potato accessions that are resistant to aphids and viruses. We subjected 174 advanced potato lines to intensive selection for resistance to these pests (aphids and viruses). A single potato line (HPR24) that has consistently expressed resistance to aphids was crossed with a standard cultivar, Chieftain, to produce an F1 population. Thirty HPR24 F1 progeny were tested for aphid survivorship, development, reproduction and adult longevity. Intrinsic rates of increase for green peach aphid ranged from 0.042 to 0.311 and for potato aphid, this value ranged from -0.077 to 0.161. All values are substantially lower than those obtained on aphid-susceptible potato cultivars. In addition, we are using electrical penetration graphs to record feeding behavior on resistant and susceptible plants. With
these techniques, we will be able to ascertain whether the resistance(s) expressed in our potato lines are due to antixenosis (non-preference) or antibiosis (toxicity), and to use marker assisted selection to guide aphid resistance integration into current potato cultivars. To slow spread of PVY in the field, we have employed a cultural practice of planting a crop border alongside a seed potato crop to intercept immigrating viruliferous aphids before they land on potato. Crop borders have been shown to reduce PVY spread by more than 60%. But because crop borders were first developed prior to the establishment of soybean aphid we re-evaluated effectiveness of crop borders in replicated field trials. In 2004 and 2005, experiments were planted at two locations, Grand Forks, ND and Rosemount, MN. Crop border treatments were fallow (no border), soybean, potato, and spring planted winter wheat. We also compared untreated crop borders with insecticide treated crop borders. We harveste 100
random tubers from each plot. The 6000 tubers were tested for PVY infection. Using a visual assessment of PVY infection, crop borders (soybean, wheat, or potato) compared to no border (fallow) were significant lower in PVY (X2 = 30.36, P-value = 0.000001). When daughter tubers were indexed serologically there were no significant differences in virus levels between using a border and no border. The difference between visual and serological tests may be due to late season infection that is harder to detect visually or to strain of PVY, some which are essentially symptomless. Based on ELISA tests we concluded that PVY infection was not reduced by crop borders, but this failure to reduce PVY spread was likely due to high initial infection rates in planted seed (26%). Another nonpersistently transmitted virus, Potato virus S (PVS) which had a low initial infection rate (<4%), crop borders did significantly reduce transmission (LRT P-value: 0.016). Insecticide treatment of borders had
inconsistent effects on spread of non-persistent viruses and no effect on PLRV. PLRV infection rates were not influenced by crop borders.
Impacts
Crop borders will not prevent spread of PVY if the crop begins heavily infected. Crop borders may in fact increase spread of virus if abundant inoculum is present in the crop. This research reiterates the need to plant the cleanest seed available for seed increase. Although many years away from development of aphid and virus resistant potato cultivars, we have developed a selection that has maintained strong aphid resistance (HPR24). Further work characterizing the type of resistance (antibiosis or non-preference) will help direct future breeding efforts.
Publications
- Olson, K., T. Badibanga, E. Radcliffe, M. Carroll, I. MacRae, and D. Ragsdale. Economic analysis of using a border treatment for reducing organophosphate use in seed potato production. Staff. Paper P04-8, Department of Applied Economics, University of Minnesota, 2004.
- Ragsdale David W., Edward B. Radcliffe, and Kathy L. Flanders. 2006. Managing Aphids and Leafhoppers. In D. Johnson, [ed]. Potato Health Management, American Phytopath. Society Plant Health Management Series, APS Press, St. Paul, MN.
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Progress 01/01/04 to 12/31/04
Outputs
Cultural control practices to stimulate early onset of fungal pathogens that attack soybean aphid were evaluated in 2004. Factors investigated were row spacing (7 vs 30" rows) and high (250,000) and low (125,000) plant populations per acre were used to create an earlier canopy closure to provide environmental conditions conducive to fungal epizootics. The first fungal infected aphid was detected in plots on 24 July, but relative humidity within the canopy at less than 50% in all treatments due primarily to a lack of rainfall and relatively warm overnight temperatures that did not reach dewpoint prevented an epizootic from developing in any of the experimental treatments. Based on this one year of data collection, cultural manipulation of row spacing and plant density was not sufficient to stimulate an early onset of epizootics to help reduce aphid density in soybean. Work will continue on this in 2005 to include the use of a cover crop (rye) in organic soybean
production to determine if a more complex agroecosystem will assist in an earlier onset of fungal epizootics on soybean aphid. In potato we documented that application of methamidophos to only the first 18 m of the field timed when green peach aphid was first detected resulted in treatment of only 38.5 of 730 hectares in the EPA funded on-farm demonstration project. On average growers saved $23.65 per acre using border treatments. There was no increase in virus incidence noted by producers between fields where a border treatments was used compared to fields where the entire field was treated. An interview of all participating growers stated that all are planning on using border application next year because of the substantial cost saving realized will pay for the increased scouting costs associated with detecting when aphids first arrive in the field. We documented that Potato virus Y (PVY) infection spread to healthy potato plants adjacent to planting skips or gaps in a field more
readily compared to portions of the same field where no skips were found. We hypothesize that the gaps created by planting skips or roguing (removal of infected plants early in the season) makes the surrounding plants more attractive to winged aphids. These preliminary data suggest that operations just as roguing may need to be modified.
Impacts
1. Soybean aphid is now known to be a vector of potato virus Y and seed potato growers which have soybean adjacent to seed potato fields need to consider managing aphids in soybean. 2. Green peach aphid can be effectively controlled in seed potato fields by only treating field edges (60ft) in the Red River Valley. This research demonstrated on 27 grower fields that treating field edges only can save 75% in treatment costs for the first application of insecticide to control green peach aphid. 3. Advanced potato breeding lines have been characterized for resistance to aphids and viruses. Sources of this resistance is being characterized so more crosses can be made in an interdisciplinary effort to use wild potato germplasm as a source of resistance to aphids and the viruses they transmit
Publications
- McCornack, B., D. W. Ragsdale, and R. C. Venette. 2004. Demography of Soybean Aphid (Homoptera: Aphididae) at Summer Temperatures. J. Econ. Entomol. 97(3): 854-861.
- Skinner, L. C., D. W. Ragsdale, R.W. Hansen, M.A. Chandler and R.D. Moon. 2004. Temperature-dependent development of overwintering Aphthona lacertosa and A. nigriscutis (Coleoptera: Chrysomelidae), two flea beetles introduced for the biological control of leafy spurge, Euphorbia esula. Environ. Entomol. 33: 147-154.
- Ragsdale, D. W., D. V. Voegtlin and R. J. ONeil. 2004. Soybean Aphid Biology in North America. Annals Entomol. Soc. Amer. 97: 204-208.
- Heimpel G. E., D. W. Ragsdale, R. C. Venette, K. Hopper, R. J. ONeil, C. Rutledge, and Z. Wu. 2004. Prospects for importation biological control of the soybean aphid: anticipating potential costs and benefits, Ann. Entomol. Soc. Amer. 97: 249-258.
- Wu, Z., D. Schenk-Hamlin, Zhan, D. W. Ragsdale and G. E. Heimpel. 2004. The soybean aphid in China an historical review. Ann. Entomol. Soc. Amer. 97: 209-218.
- Venette, R. C and D. W. Ragsdale. 2004. Assessing the invasion by soybean aphid (Homoptera: Aphididae): where will it end? Ann. Entomol. Soc. Amer. 97: 219-226.
- Hodgson, E. W., E. C. Burkness, W. D. Hutchison, and D. W. Ragsdale. 2004. Enumerative and Binomial Sequential Sampling Plans for Soybean Aphid (Homoptera: Aphididae) in Soybean. J. Econ. Entomol. 97(6): 2127-2136.
- Davis, J. A., E. B. Radcliffe, D. W. Ragsdale. 2005. Soybean aphid, Aphis glycines Matsumura, a new vector of Potato Virus Y in potato. Amer. J. Potato Res. 81: 101-105.
- McCornack, B. P., M. A. Carrillo, R. C. Venette, and D.W. Ragsdale. 2005. Physiological constraints to the overwintering distribution of the soybean aphid (Homoptera: Aphididae). Environ. Entomol. (in press).
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Progress 01/01/03 to 12/31/03
Outputs
Soybean aphid, Aphis glycines, was confirmed as a vector of Potato virus Y (PVY). Soybean aphid was first found in North American in July 2000. Soybean aphid can now be found throughout Minnesota. Since soybean aphid is an efficient vector of other potyviruses, we tested if this aphid could also transmit another potyvirus, PVY. We successfully transmitted PVY from potato to potato by soybean aphid in greenhouse arena tests. We also used single aphids and in groups of 5, to measure transmission efficiency which ranged from 27% to 65%. Soybean aphid transmitted all known PVY strains present in our inoculum source, PVYO, PVYN, PVYN/NTN. Recombinant PVYO:N variants were also transmitted. In transmission experiments, soybean aphid transmitted PVYO more frequently than the other strains but definitive experiments need to be designed to confirm this finding. This is the first report of A. glycines transmitting PVY. To control the green peach aphid in seed potato fields,
growers almost exclusively rely on an organophosphate insecticide, methamidophos, (Monitor). Previous research has shown that more than 90% of the green peach aphids can be found within the first 18m of a field edge in the first 10 days following colonization. This finding suggested that aphid control in the Red River Valley could be obtained by treating only field margins. We tested this assumption in 27 seed potato fields in Minnesota and North Dakota that by treating potato field borders alone and sampling aphids 3 and 7 days following treatment. Pretreatment counts showed that border treatment exposed 91% of the green peach aphid population present in these fields to insecticides. Post treatment evaluation showed that green peach aphids were significantly reduced and that the initial treatment of potato fields for green peach aphid could be a border application rather than treating the entire field, thereby reducing methamidophos use by more than 75%. A final area of investigation
has been to test advanced potato breeding lines for resistance to aphids and viruses, specifically PVY and Potato leafroll virus (PLRV). Over the past 6 years we subjected 174 potato lines from the Minnesota Potato Breeding Program and 134 lines from other programs to intensive selection for resistance to PVY, PLRV and aphids. Of these, 21 potato lines have been found to consistently express field resistance to both PVY and PLRV, 35 are resistant to PVY but susceptible to PLRV, and 9 are resistant to PLRV but susceptible to PVY. We have identified durable multigenic resistance and we are currently trying to characterize the source of this resistance. These clones have subsequently been tested in the greenhouse for their ability to support green peach aphid and potato aphid (Macrosiphum euphorbiae) population development. From this research, we have identified 12 lines resistant to M. persicae and 12 lines resistant to M. euphorbiae. None of the lines are resistant to both aphids. We
have made 900 crosses from these lines which have produced 26,000 seeds which will be tested in 2004.
Impacts
1. Soybean aphid is now known to be a vector of potato virus Y and seed potato growers which have soybean adjacent to seed potato fields need to consider managing aphids in soybean. 2. Green peach aphid can be effectively controlled in seed potato fields by only treating field edges (60ft) in the Red River Valley. This research demonstrated on 27 grower fields that treating field edges only can save 75% in treatment costs for the first application of insecticide to control green peach aphid. 3. Advanced potato breeding lines have been characterized for resistance to aphids and viruses. Sources of this resistance is being characterized so more crosses can be made in an interdisciplinary effort to use wild potato germplasm as a source of resistance to aphids and the viruses they transmit
Publications
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of Colorado potato beetle on potatoes using soil applied insecticides and treated potato seed, 2002. Arthropod Management Tests, 28: E51.
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of potato leafhopper on potatoes using foliar insecticides, 2002. Arthropod Management Tests, 28: E52.
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of potato leafhopper on potatoes using soil applied insecticides and treated potato seed, 2002. Arthropod Management Tests, 28: E53
- Skinner, L.C., D.W. Ragsdale, R.W. Hansen, M.A. Chandler and R.D. Moon, 2004. Temperature dependent development of overwintering Aphthona lacertosa and A. nigriscutis (Coleoptera: Chrysomelidae), two flea beetles introduced for the biological control of leafy spurge, Euphorbia esula. Environmental Entomology (in press).
- Radcliffe, E. B., D. W. Ragsdale and R. A. Suranyi. 2003. IPM case studies seed potato, In. Aphids as Crop Pests, H. F. van Emden and R. Harrington [eds.]. CABI Publishing, Wallingford, U.K. (accepted for publication)
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of aphids on potatoes using foliar insecticides, 2002. Arthropod Management Tests, 28: E48.
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of aphids on potatoes using soil applied insecticides and treated potato seed, 2002. Arthropod Management Tests, 28: E49.
- Davis, J. A. E. B. Radcliffe, and D. W. Ragsdale. 2003. Control of Colorado potato beetle on potatoes using foliar insecticides, 2002. Arthropod Management Tests, 28: E50.
- Legg, D. E., S. M. Van Vleet, D. W. Ragsdale, R. W. Hansen, B. Chen-Charpentier, L. Skinner, and J. E. Lloyd. 2003. Required number of location years for estimating functional lower developmental thresholds and required thermal summations of insects: first emergence of Apthona nigriscutis Foudras as an example. International Journal of Pest Management 49: 319-325.
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Progress 01/01/02 to 12/31/02
Outputs
Aphid-transmitted potato viruses have caused unprecedented losses to seed potato producers in the northern Great Plains since 1995. This project focuses on the fundamental drivers of this epidemic by evaluating the level of aphid-transmitted potato viruses in seed potato fields along with vector abundance and species diversity. Unfortunately, economic losses because of aphid-transmitted viruses have been so great that seed producers are going out of business with more than half of the seed growers no longer producing seed and consequently a 50% reduction in seed potato acreage compared to acreage entered in 1995. We initiated an area-wide aphid monitoring network, Aphid Alert, which has run continuously since 1998. Data from this suction trap and pan-trap network provides growers with near real-time information on flight activity of key aphid vectors. Prior to the establishment of Aphid Alert, potato growers had no information on which to base aphid pest management
decisions. Crop scouting will detect aphids but usually some weeks after aphids first arrive. With aphid-transmitted viruses, particularly potato leafroll virus, aphid densities that exceed more than 3-10 aphids per 100 leaves translate into increased virus spread. Aphid Alert provides an early warning of immigrating winged aphids and many potato growers make their pest management decisions using the regional trapping data provided by Aphid Alert. One estimate of the value of Aphid Alert by the Northern Plains Potato Growers Association was that by following Aphid Alert advisories the Minnesota and North Dakota potato industry saved over $6 million in 2000 and 2002. Additional work on how green peach aphids colonizes potato fields has shown that initial colonization is confined to field margins. Typically, for the first 10 days following colonization, more than 90% of the aphids are within 20 m of the field margin. We have suggested that growers use this information coupled with Aphid
Alert to focus scouting and treatment on field margins for at least the first insecticide spray targeted for aphids. Conservatively, this practice could save growers 70-80% for the first application and in some fields no further treatment would be needed the rest of the season. Growers are very receptive to this approach because it has the potential to greatly reduce their control costs. We also continue to build weather based models that can predict green peach aphid immigration into the northern Great Plains. Variables associated with the model include isolines where winter temperatures drop below -14C, wind events that are of sufficient duration and point of origin that they likely are to contain winged green peach aphids and local temperatures that are suitable for population growth. This is an extremely complex model, but we are confident we will be able to predict whether aphids will be below normal, normal or at outbreak levels in any year by analyzing these factors.
Impacts
Seed potato producers are facing unprecedented losses due to aphid-transmitted plant viruses. Traditional scouting and crop protection chemicals do not provide control. This project informs growers what cultural practices favor virus spread, how they can limit virus spread without having to use additional insecticidal sprays and educates growers and crop professionals on the factors that are driving this current epidemic.
Publications
- Ruano-Rossil, Jorge M., E. B. Radcliffe and D. W. Ragsdale. 2002. Disruption of entomopathogenic fungi of green peach aphid, Myzus persicae (Sulzer), by fungicides used to control potato late blight. Proceedings: Aphids in a New Millenium, VIth Int. Symp. on Aphids, Rennes, France 3-7 Sept. 2001. (accepted for publication).
- Radcliffe, E. B. and D. W. Ragsdale. 2002. Aphid transmitted potato viruses: the importance of understanding vector biology. Amer. J. Pot. Res. 79:353-386.
- Legg, D. E., S. M. Van Vleet, D. W. Ragsdale, R. W. Hansen, B. Chen-Charpentier, L. Skinner, and J. E. Lloyd. 2002. Required number of location-years for estimating functional lower developmental thresholds and required thermal summations of insects: first emergence of Apthona nigriscutis Foudras as an example. International Journal of Pest Management, (In press) Accepted for publication, October 2001.
- Legg, D. E., S. M. Van Vleet, D. W. Ragsdale, R. W. Hansen, and J. E. Lloyd. 2002. Phenology Models for first emergence of aldult Apthona nigriscutis (Coleoptera: Chrysomelidae), a biological control agent of leafy spurge (Euphorbiaceae). Environ. Entomol. 31: 348-353.
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Progress 01/01/01 to 12/31/01
Outputs
Funding for MN 17-049 was augmented by competitive grants from USDA NC-IPM grants program ('Site Specific Management of Potato Virus Vectors') and the University of Minnesota Rapid Response Fund. We provided potato producers in Minnesota and North Dakota with information real-time information on aphid abundance using a multi-state aphid trapping network (28 traps in 5 states). Information on aphid abundance and movement is provided to growers via an e-mail alert, a surface mail hard copy weekly newsletter, `Aphid Alert' plus information is posted on the World Wide Web (http://www.ipmworld.umn.edu/alert.htm). The aphid trapping network was expanded to SE Minnesota to encompass areas of the state recently invaded by the soybean aphid to determine if traps could provide information on movement of this new exotic aphid. Traps were serviced weekly with the aphids sorted to species and abundance recorded. The 'Aphid Alert' trapping network is unique in North America both in
area of coverage and outreach to clientele. The number of growers participating by hosting traps on their farms has increased each year, from 12 in 1998, to 28 in 2001. Increases in the number of trapping sites has been due solely to additional grower participation since no grower has chosen to withdraw from the project. A survey of seed potato growers revealed that 98% of respondents found the information provided by the Aphid Alert project useful and 78% indicated they used this information in making pest management decisions. In 2001, green peach aphid colonization of potato fields was the lowest ever recorded. Other aphids routinely monitored (cereal aphids and others) were also the lowest ever recorded. It appears that the summer of 2001 provided seed potato growers with an opportunity to increase seed in a climate of very low aphid abundance thereby limiting spread of aphid transmitted viruses. A majority of green peach aphids captured in August are carrying potato leafroll
virus determined by RT-PCR analysis of aphids captured in suction traps. This indicates that these aphids are coming off potatoes, most likely processing potato fields where aphids are considered occasional pests. The NC-IPM project focuses on site-specific management of green peach aphid. Here we demonstrated to potato producers that green peach aphid colonizes field edges, giving producers a window of opportunity to treat field edges before the entire field is colonized. Growers participating in the pilot project were able to reduce treatment costs by 72.7% ($1417 per field) in chemical costs alone. Overall, the Aphid Alert project has demonstrated an excellent multi-institutional cooperation among the University of Minnesota, the Red River Valley Potato Growers Association, the Minnesota Department of Agriculture, and the North Dakota State Seed Department. Ultimately, successful management of the current potato virus epidemic is largely dependent upon such close cooperation among
growers, state regulatory agencies, researchers and extension specialists.
Impacts
Seed potato producers in the Northern Great Plains are provided real-time information on regional movement of aphid vectors of potato viruses. This information is used by growers to make management decisions such as when to treat fields with insecticides or in lieu of insecticides, when to top-kill the crop to prevent further virus spread. Without this vital information growers would be operating in an information vacuum. Processing potato growers are also impacted by the site-specific treatment recommendations produced by this project. We now know that green peach aphids colonize field edges first and that treatment of field perimeters will reduce chemical costs by nearly 73%. Treatment of field edges will reduce the number of winged green peach aphids flying in August already carrying potato leafroll virus.
Publications
- Radcliffe, E. B. and D. W. Ragsdale. 2001. Aphid transmitted potato viruses: the importance of understanding vector biology. Amer. J. Pot. Res. (invited review - accepted for publication).
- Novy, R.G., A. Nasruddin, D.W. Ragsdale, and E.B. Radcliffe. 2001. Genetic Resistance to Potato Leafroll Virus (PLRV), Potato Virus Y (PVY), and Green Peach Aphid (Myzus persicae) in Progeny of Solanum etuberosum. Amer. J. Potato Research, Accepted for publication, August 2001.
- Radcliffe, E.B., D.W. Ragsdale, & R.A. Suranyi. 2002. IPM case studies - seed potato. In: H.F. van Emden & R. Harrington (eds.) Aphids as Crop Pests. CABI, Wallingford, U.K.
- Ragsdale, D. W., E. B. Radcliffe, and C. D. DiFonzo. 2001. Epidemiology and Field Control of PVY and PLRV, pp. 237-270. In G. Loebenstein and P. Berger, A. A. Brunt and R. Lawson [eds.] Virus and virus-like diseases of potatoes and production of seed-potatoes, Kluwer Academic Publishers, The Netherlands, 460 pp.
- Radcliffe, E. B., Suranyi, R., D. W. Ragsdale, and I. MacRae. 2001. Aphid Alert, 2001, 10 weekly articles written and distributed to potato growers in Minnesota and North Dakota. http://ipmworld.umn.edu/alert.htm
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Progress 01/01/00 to 12/31/00
Outputs
Funding for MN 17-049 was augmented by competitive grants from USDA NC-IPM grants program, two potato grower organizations, and the University of Minnesota Rapid Response fund. We provided potato producers in Minnesota and North Dakota with information on how to manage aphids to reduce the impact of aphid transmitted viruses in seed and commercial potato production. We used an aphid-trapping network to provide near real-time information to growers on aphid flight activity. These data were reported on our Aphid Alert web site located at: http://www.ipmworld.umn.edu/alert.htm, in a weekly newsletter mailed to all seed potato producers in MN and ND, and through an e-mail version of the newsletter sent to over 300 growers, consultants, extension specialists and crop professionals throughout the upper Midwest and Canada. In 2000, aphid traps were operated at 12 locations in Minnesota, 7 in North Dakota, 2 in Wisconsin, and 1 each in South Dakota, and Nebraska. Trap
locations in the Red River Valley of Minnesota and North Dakota were about 70 miles apart, providing information on phenology and numerical abundance of the aerial aphid fauna in the region. Traps were serviced weekly with the aphids sorted and counted to species. The 'Aphid Alert' trapping network is unique in North America both in area of coverage and outreach to clientele. The positive impact of the 'Aphid Alert' project is shown by the enthusiastic participation of growers. The number of growers participating by hosting traps on their farms has increased each year, from 12 in 1998, to 24 in 2000. Increases in the number of trapping sites has been due solely to additional grower participation since no grower has chosen to withdraw from the project. A survey of seed potato growers revealed that 98% of respondents found the information provided by the 'Aphid Alert' project useful and 78% indicated they used this information in making pest management decisions. We demonstrated that
green peach aphid colonization of potato fields begins at the field margins. Selectively targeting pesticide applications to only these areas (site-specific management) offers growers a means of reducing the costs and the environmental impact associated with pesticide use without compromising overall control. The 'Aphid Alert' project was the first to successfully demonstrate that site-specific management of green peach aphids is possible in a grower's field, and the participating grower achieved a 70% reduction in treatment cost. Overall, the Aphid Alert project has demonstrated an excellent multi-institutional cooperation among the University of Minnesota, the Red River Valley Potato Growers Association, the Minnesota Department of Agriculture, and the North Dakota State Seed Department. Ultimately, successful management of the current epidemic is largely dependent upon such close cooperation among growers, state regulatory agencies, researchers and extension specialists.
Impacts
A survey of seed potato growers revealed that 98% of respondents found the information provided by the 'Aphid Alert' project useful and 78% indicated they used this information in making pest management decisions. The 'Aphid Alert' project was the first to successfully demonstrate that site-specific management of green peach aphids is possible in a grower's field, and the participating grower achieved a 70% reduction in treatment cost.
Publications
- Stamm Katovich, E. J., Ragsdale, D. W., Skinner, L. C., and R. L. Becker. 2000. Effect of Galerucella spp. feeding on seed production in Lythrum salicaria. Weed Science (accepted July 2000)
- Newman, R. M., D. W. Ragsdale, A. Milles, C. Oien. 2000. Overwinter habitat and the relationship of overwinter to in-lake densities of the milfoil weevil, Euhrychiopsis lecontei, a Eurasian watermilfoil biological control agent. J. Aquatic Plant Management, Accepted July 2000.
- Munyaneza, J., E, B, Radcliffe and D. W. Ragsdale. 2000. Control of Colorado potato beetle on potatoes, 1999. Arthropod Management Tests 2000, 25: 140-141.
- Munyaneza, J., E, B, Radcliffe and D. W. Ragsdale. 2000. Control of potato leafhopper on potatoes, 1999. Arthropod Management Tests 2000, 25: 141-142.
- Munyaneza, J., D. W. Ragsdale and E. B, Radcliffe. 2000. Control of green peach aphid on potatoes, 1999. Arthropod Management Tests 2000, 25: 143.
- Munyaneza, J., D. W. Ragsdale and E. B, Radcliffe. 2000. Control of potato insect pests using treated potato seeds, 1999. Arthropod Management Tests 2000, 25: 142-145.
- Munyaneza, J., D. W. Ragsdale and E. B, Radcliffe. 2000. Control of potato leafhopper and green peach aphid using reduced rates of insecticides, 1999. Arthropod Management Tests 2000, 25: 145-146.
- Munyaneza, J., D. W. Ragsdale and E. B, Radcliffe. 2000. Control of potato leafhopper adults using reduced rates of insecticides, 1999. Arthropod Management Tests 2000, 25: 145-146.
- Munyaneza, J., E. B. Radcliffe, and D. W. Ragsdale. 2000. Control of green peach aphid using reduced rates of insecticides, 1999. Arthropod Management Tests 2000, 25: 147-148.
- Ragsdale, D. W., E. B. Radcliffe, and C. D. DiFonzo. 2000. Epidemiology and Field Control of PVY and PLRV, In G. Loebenstein and P. Berger, A. A. Brunt and R. Lawson [eds.] Virus and virus-like diseases of potatoes and production of seed-potatoes, Kluwer Academic Publishers, The Netherlands.
- Radcliffe, E. B., Suranyi, R., D. W. Ragsdale, I. MacRae, and B. Lockhart. 2000. Aphid Alert, 2000, 12 weekly articles written and distributed to potato growers in Minnesota and North Dakota.
- Suranyi, R., I. V. MacRae, D. W. Ragsdale, and E. B. Radcliffe. 2000. Site specific management of green peach aphid in seed potatoes. Amer. J. Potato Res. 77: 420 (abstract)
- Newman, R.M., D.W. Ragsdale, A. Loos and J.L. Foley. 2001. Factors limiting populations of the native milfoil weevil, a control agent of Eurasian watermilfoil. X International Symposium on the Biological Control of Weeds. 6 July 1999, Bozeman, MT. (invited for talk). [Pages 427-428 in N.R. Spencer, ed. 2000. Proceedings of the X International Symposium on the Biological Control of Weeds, Montana State University, Bozeman, MT]
- Suppression of entomopathogenic fungi of green peach aphids, Myzus persicae, (Sulzer) by late blight fungicides. 2000. Ph.D. dissertation, University of Minnesota, 98 pp.
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Progress 01/01/99 to 12/31/99
Outputs
An aphid trapping network consisting of 14 suction traps and 56 pan traps was established in Minnesota and North Dakota in 1999. Colleagues in Manitoba independently operated an additional 5 trapping sites so that the entire Red River Valley of the North has aphid flight activity monitored throughout the growing season. Additional traps were distributed throughout the seed producing areas of Minnesota and North Dakota. Aphid trapping data were supplied to growers, consultants, industry and University contacts via e-mail, internet and a weekly publication "Aphid Alert" was mailed to over 300 recipients. A survey of those who receive this information was conducted and 31.7% of the surveys were returned. In 1999, no green peach aphid captured and tested using immunocapture PCR contained potato viruses. This demonstrated that green peach aphids were not likely entering the field carrying PVY or PLRV but that virus was being spread within a seed potato field because
inoculum was available. These data underscore the importance of eliminating virus sources in seed potato field. Isolation distances of seed potato fields from commercial potatoes need to be determined and is the focus of the 2000 field research.
Impacts
Based on a survey of those receiving the "Aphid Alert" newsletter, 93.6% of growers indicated they used the information to make management decisions.
Publications
- Radcliffe, E. B., Suranyi, R., D. W. Ragsdale, I. MacRae, and B. Lockhart. 1999. Aphid Alert: A research/outreach initiative addressing potato virus problems in the northern Midwest USA.
- Ragsdale, D. W. 1999. Colorado Potato Beetle, for Midwest VegEdge: Vegetable IPM Resource for the Midwest.
- Radcliffe, E. B., Suranyi, R., D. W. Ragsdale, I. MacRae, and B. Lockhart. 1999. Aphid Alert, 1999, 14 weekly articles written and distributed to potato growers in Minnesota and North Dakota.
- Radcliffe, E. B., A. Lagnaoui, and D. W. Ragsdale. 1999. Fungicides Impact Aphid Control.
- Radcliffe, E. B., Suranyi, R., D. W. Ragsdale, I. MacRae, and B. Lockhart. 1999. Aphid Alert: A research/outreach initiative addressing potato virus problems in the northern Midwest.
- Ragsdale, D. W. and E. B. Radcliffe. 1999. A new threat from an old pest: green peach aphid. Valley Potato Grower 64(110): 12, 14.
- Ragsdale, D. W., E. B. Radcliffe, and C. D. DiFonzo. 1999. Epidemiology and Field Control of PVY and PLRV, In G. Loebenstein and P. Berger, A. A. Brunt and R. Lawson [eds.] Virus and virus-like diseases of potatoes and production of seed-potatoes, Kluwer Academic Publishers, The Netherlands.
- Suranyi, R., C. Longtine, D. Ragsdale, and E. Radcliffe. 1999. Controlling leafhoppers with below-label rates. Valley Potato Grower 64(113): 11-13, 16.
- Suranyi, R. A., C. A. Longtine, D. W. Ragsdale, E. B. Radcliffe. 1999. Control of Colorado potato beetle, 1998A. Arthropod Man. Tests. 24: 169.
- Longtine, C. A., R. A. Suranyi, D. W. Ragsdale, E. B. Radcliffe. 1999. Colorado potato beetle control on potatoes with foliar insecticide sprays, 1998. Arthropod Man. Tests. 24: 155.
- Longtine, C. A., R. A. Suranyi, D. W. Ragsdale, E. B. Radcliffe. 1999. Control of green peach aphid, 1998. Arthropod Man. Tests. 24: 155-156.
- Longtine, C. A., R. A. Suranyi, D. W. Ragsdale, E. B. Radcliffe. 1999. Control of Colorado potato beetle, 1998. Arthropod Man. Tests. 24: 156-158.
- Longtine, C. A., R. A. Suranyi, D. W. Ragsdale, E. B. Radcliffe. 1999. Control of potato leafhopper, 1998. Arthropod Man. Tests. 24: 158.
- Longtine, C. A., R. A. Suranyi, D. W. Ragsdale, E. B. Radcliffe. 1999. Control of potato leafhopper and green peach aphid using reduced rates of insecticides, 1998. Arthropod Man. Tests. 24: 158-160.
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Progress 01/01/98 to 12/31/98
Outputs
Since 1993, potato growers in Minnesota and North Dakota have experienced devastating and escalating economic losses due to aphid transmitted potato viruses, specifically potato leafroll virus (PLRV) and potato virus Y (PVY). Potatoes are planted from vegetative tubers so a potato plant is only as healthy as the tuber from which it is grown. Strict regulations are set by law and enforced by the Minnesota Department of Agriculture to keep seed potatoes as disease free as possible using tolerance levels that range from 0 to 1% disease. Once a seed lot exceeds legal tolerance it cannot be sold as seed the following year often resulting in total loss to the grower. Potato seed lot rejections increased to near catastrophic proportions in the 1997 seed crop, with 31% of seed potato lots rejected for above tolerance levels. Preliminary data indicates that rejection rates in 1998-99 winter trials exceeds 50%. Dozens of seed growers, some in business for multiple generations,
are facing financial ruin. Also, for the first time in this production area, commercial potato growers whose crop is used for processing (frozen potato products) experienced significant quality losses. Losses were caused by a tuber condition called net necrosis (caused by PLRV) which resulted in loss of grade and for some growers outright rejections of potatoes at the processing plant. This research project conducted the following in 1998 to assist growers in this crisis . 1. Set up an aphid monitoring network (five sites in Minnesota, two in North Dakota in 1998). 2. Collected GPS data for statistical analysis (GIS) of the spatial dynamics of virus spread. 3. Evaluate three potential isolation sites at Minnesota Agricultural Experiment Stations. 4. Develop an immunocapture-PCR diagnostic test that can detect PLVR in a single aphid to forecast virus epidemic. 5. Publish a weekly newsletter, Aphid Alert distributed to all seed potato growers in the two states by mail and the internet,
<http://ipmworld.umn.edu/alert.htm>.
Impacts
(N/A)
Publications
- Longtine, C. A., E. B. Radcliffe and D. W. Ragsdale. 1998. Control of Colorado potato beetle, 1997B. Arthropod Pest Management 23: 128.
- Longtine, C. A., E. B. Radcliffe and D. W. Ragsdale. 1998. Laboratory tests for Colorado potato beetle control, 1997. Arthropod Pest Management 23: 371.
- Radcliffe, E. B. and D. W. Ragsdale. 1998. Aphids cause big problems for industry. Valley Potato Grower 63(110): 4, 6, 31.
- Radcliffe, E. B. and D. W. Ragsdale. 1998. Initiative to address viruses in seed potatoes. Valley Potato Grower 63(113): 20-21.
- James, P. J., R. D. Moon, and D. W. Ragsdale. 1998. Serum and skin surface antibodies and their association with sheep biting lice, Bovicola ovis, on experimentally infested sheep. Med. Vet. Entomol. 12: 276-283. Ragsdale, D. W. 1998. Ecological impacts of transgenic potatoes - an entomological perspective. Amer. Pot. J. (in press)
- Longtine, C. A., R. A. Suranyi, T.J. Connors, D. W. Ragsdale, and E. B. Radcliffe. 1998. Control of green peach aphid on potato, 1997. Arthropod Pest Management 23: 127.
- Longtine, C. A., D. W. Ragsdale, and E. B. Radcliffe. 1998. Control of Colorado potato beetle, 1997A. Arthropod Pest Management 23: 127.
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Progress 01/01/97 to 12/31/97
Outputs
Fungicides used to protect the U.S. potato crop from potato late blight, the disease that caused the Irish potato famine in 1845-46, are indirectly causing green peach aphid populations to increase. We discovered that fungicides used for late blight control are harmful to parasitic fungi that attack green peach aphids. In irrigated potatoes the proportion of green peach aphids parasitized by various fungi were Entomophthora planchonicana (60%), Conidiobolus obscurus (23%) and Pandora neoaphidis (3%). In nonirrigated potatoes, aphids were infected with P. neoaphidis (48%), C. obscurus (24%), Zoophthora radicans (9%)and E. planchonicana (8%). All fungicides tested were detrimental to the parasitic fungi and peak aphid populations were 3 to 10-fold larger than those in untreated plots. Since 1993, Ridomil-resistant strains late blight strains have replaced Ridomil-sensitive strains, to protect their crop. Insecticides used for Colorado potato beetle and potato leafhopper
control trigger green peach aphid outbreaks by eliminating beneficial insects. The combination of insecticide and fungicide treatments creates environments with no natural enemies to keep green peach aphid populations in check and aphid populations explode, doubling every 2 days. Aphid populations can increase to densities that cause plants to die and in our trials yield losses averaged 153 cwt/acre. Our goal is to identify management practices which are least disruptive to natural enemies of green peach aphids.
Impacts
(N/A)
Publications
- Ragsdale, D.W., Radcliffe, E.B., Ruano-Rossil, J., Gudnestad, N., and Secor, G. 1997. Late Blight Fungicides Linked to Increases in Green Peach Aphids in Potato, Midwest Biological Control News. (4(12): 1-3.
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Progress 01/01/96 to 12/30/96
Outputs
Experiments were conducted at three locations, Rosemount, Staples, and Grand Forks, North Dakota. Some fungicides used to control late blight in potato have detrimental effects on entomopathogenic fungi that help control aphids colonizing potato. At the end of the season, green peach aphid populations were 14-fold higher when some EBDC fungicides were used than when other formulations or active ingredients were used. The organotin and copper containing fungicides had intermediate effects on aphid populations with the lowest aphid populations found when chlorothalonil was used alone or in combination with section 18 materials (Acrobat, Tattoo, Diva and Polyram). Studies on the impact various pest management practices have on aphid populations and subsequent spread of potato leafroll virus (PLRV) are being investigated. It appears that potato leafhopper damage to potatoes affects the liklihood that tubers will become infected with PLRV. Cage studies were conducted to
corroborate this interaction.
Impacts
(N/A)
Publications
- DIFONZO, C.D., RAGSDALE, D.W., RADCLIFFE, E.B., GUDMESTAD, N. C., & SECOR, G.A. 1996. Crop borders reduce potato virus Y incidence in seed potato. Annals Appl. Biol. 129:xxx-xxx.
- DIFONZO, C.D., RAGSDALE, D.W., RADCLIFFE, E.B, GUDMESTAD, N. C., & SECOR, G.A. 1996. Seasonal abundance of aphid vectors of potato virus Y (PVY) in the Red River Valley of Minnesota and North Dakota. J. Econ. Entomol (in press).
- DIFONZO, C.D., RAGSDALE, D.W., RADCLIFFE, E.B., GUDMESTAD, N. C., & SECOR, G.A. 1995. IPM Results Minnesota.
- RADCLIFFE, E. B., RAGSDALE, D.W. 1996. Late blight fungicides have an impact on aphid control. Valley Potato Grower 61:16-17, 21.
- DIFONZO, C.D., RAGSDALE, D. W., RADCLIFFE, E.B. 1996. Use of reflective mulches to reduce potato virus Y Potyvirus incidence in seed potato. Congress of IsraeliPhytopathological Society. July 1996.
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Progress 01/01/95 to 12/30/95
Outputs
Fall, 1994: All plots from 4 experiment station trials & 12 on-farm demo. trialswere harvested & approx. 26,000 tubers were shipped to Homestead, FL for winter trials. Plots were destroyed in late Nov. when 24 inches of rain fell in 48h a few days after planting. An attempt was made to re-sample some of the field experiments in MN. but tubers were frozen or frost damaged. No further evaluation of field plots was undertaken. A survey was sent to all commercial & seed potato growers in N. Dakota & MN. in Sept. Included was info. on pest mgmt. strategies for all potato pests, including adoption of crop borders by seed potato growers. Results of the survey are being assembled. Spring, 1995: an experiment to test the PLRV resistance & differential response to various target green peach aphid densities using 8 of the most commonly grown potato cultivars in Minn. was planted. Green peach aphid population densities were manipulated in 120 plots using foliar applications of
various insecticides. A sample of 100 tubers were collected from ea. plot (50 from rows with PLRV inoculum & 50 from adjacent rows without PLRV inoculum), shipped to Texas & planted at the Texas A&M Agric. Exp. Sta., Weslaco in Nov. Plots are scheduled for eval. Feb. 1996. Another experiment was designed to compare PLRV spread in plots with different CPB controls applied. CPB control flared aphid populations while others had no effect, e.g, esfenvalerate and Btt.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Aphid trap & bait-plant sites (11) were located in the Red River Valley of Minn.& N. Dakota. Aphid density at all sample sites in 1993 were 10 to 100 times lower than aphid density in 1992. To date, 18 aphid species have been identified from 1993 trap catches. As in 1992, grain aphids (Rhopalosiphum maidis, the corn-leaf aphid; R. padi, the oat-birdcherry aphid; Sitobion avenae, the English grain aphid), pea aphid (Acyrthosiphum pisum), sunflower aphid (Aphis helianthi), & an aphid found on Canada thistle (Capitophorus elaeagni) were the most abundant species & accounted for over 66% of the total aphids trapped. Green peach aphid, Myzus persicae, never exceeded 1% of the trap catch at any location. PVY spread to bait-plants occurred only twice in 1993 compared to 35 infected bait-plants in 1992. In experiments using crop borders to reduce PVY spread, aphid landing rates in border crops and potato were lower than landing rates found in traps placed over fallow ground.
Effect of crop border on PVY spread will be assessed once winter testing of tubers for PVY is completed. Data from both years show that neither commercial seed cutters nor hand cutting is a means of transmitting PVY in potatoes. These data are contrary to work done in North Dakota where substantial PVY spread was found in hand cut tubers. Some spread (5.9-6.5%) of PVY did occur when post-emergence but not pre-emergence cross-field cultivation ("drag-off") was practiced.
Impacts
(N/A)
Publications
- No publications reported this period.
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Progress 01/01/92 to 12/30/92
Outputs
At 13 aphid trap and bait-plant locations we installed 4 aphid traps and 16 bait-plants which were changed twice and once each week, respectively. In all, we have collected over 20,000 aphids from 1,600 pan traps and are in the process of cataloging the species abundance. In addition we evaluated PVY spread from 1,498 bait plants. PVY was detected in 35 bait plants (2.3 %) and was being spread from 2 July through 13 August with peak transmission occurring between 16 and 23 July. Peak aphid abundance was found between 30 July and 6 August. The predominate aphid species collected during this interval were Rhopalosiphum padi and Sitobion avenae, both small grain infesting species. No PVY transmission occurred after 13 August or before 2 July. Floating row covers used at a single site identified the interval of July 9-20 as the first time PVY was being spread by aphids. When using crop borders as a means if preventing PVY spread we documented that aphid landing rates on
potato are significantly reduced when potatoes are bordered by soybean. None of the mineral oil, neem oil, and whitewash treatments had any effect on aphid landing or PVY transmission when testing current season foliage for virus. Further evaluation of all the 1992 field experiments by planting progeny tubers are currently under way in a winter test plot in Florida. Continued observation of green peach aphid population dynamics indicates that it is unlikely this species is holocyclic in Minnesota.
Impacts
(N/A)
Publications
- RAGSDALE, D.W. and RADCLIFFE, E.B. 1992. PVY Research: aphid trapping network. Valley Potato Grower 58(101): 8-9.
- RAGSDALE, D.W. and RADCLIFFE, E.B. 1992. Aphid research in the Red River Valley. Valley Potato Grower 58(105): 20-21.
- DIFONZO, C.D. 1992. Spread of potato leafroll virus in differentially resistant potato cultivars, M.S. Thesis. University of Minnesota.
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Progress 01/01/91 to 12/30/91
Outputs
OBJECTIVES: Experiments were conducted on green peach aphid (GPA) transmitted potato viruses to: establish action thresholds (AT) for potato leafroll virus (PLRV) control based on GPA apterae density; determine if AT can be elevated for PLRV resistant cultivars; determine if using AT for PLRV control would cause potato virus Y (PVY) to increase, and; substantiate that wild germplasm can be selected or both GPA and PLRV resistance. SINGNIFICANT FINDINGS: PLRV resistance was lowest in Russet Burbank, intermediate in Kennebec, and highest in Cascade. PLRV spread was highly correlated with GPA apterae density with r = 0.96, 0.68, and 0.74 for Russet Burbank, Kennebec, and Cascade, respectively. An AT of 10 GPA apterae per 100 leaves (based on Russet Burbank) can be increased to 30 and 300 GPA apterae per 100 leaves for Kennebec, and Cascade, respectively. This is the first example of using an AT based on vector density to control an aphid-transmitted disease. Using an
AT to control PLRV spread does not increase the risk of PVY spread since PVY incidence did not increase until the AT was exceeded 30-fold. PVY can be spread mechanically as more infected plants (P=0.083) were found in wheel rows. All three cultivars were equally acceptable for GPA growth, suggesting that virus resistance, not GPA resistance was the mechanism.
Impacts
(N/A)
Publications
- RADCLIFFE, E.B., RAGSDALE, D.W. and FLANDERS, K.F. In press. Aphids and Leafhoppers: Economic Importance, Biology and Control. In R. C. Rowe, (ed.) APS Plant Health Management in Potato Production. APS Press, St. Paul, MN. RADCLIFFE, E.B., OUEDRAGO, G., PATTEN, S.E., RAGSDALE, D.W. and STRZOK, P. In press. Neem in Niger: A new context for a system of indigenous knowledge. In D.M. Warren, et al., eds., Indigenous knowledge systems: the cultural dimension.
- OIEN, C.T. and RAGSDALE, D.W. In press. A species-specific enzyme-linked immunosorbent assay for Nosema furnacalis (Microspora: Nosematidae). J. Invert.
- FLANDERS, K.L., RADCLIFFE, E.B. and RAGSDALE, D.W. 1991. Potato leafroll virus spread in relation to densities of green peach aphid (Homoptera: Aphididae): implications for management thresholds for Minnesota seed potatoes. J. Econ.
- RADCLIFFE, E.B., FLANDERS, K.F., RAGSDALE, D.W. and NOETZEL, D.M. 1991. Potato Pests -- Pest Management Systems for Potato Insects, pp. 587-621. In D. Pimentel, (ed.) CRC Pest Management, second edition Vol. III, CRC Press.
- RADCLIFFE, E.B. and RAGSDALE, D.W. In press. Insect Pests of Potato in the Red River Valley. In Potato Production in North Dakota, N. Dakota State Univ., Agricultural Extension Bulletin xx.
- RAGSDALE, D.W., RADCLIFFE, E.B., DIFONZO, C.D. and CONNELLY, M.S. In press. Spread of potato viruses in the field with reference to potato leafroll virus and potato virus Y, In G.W. Zehnder, et al., eds. Potato Pest Management:.
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Progress 01/01/90 to 12/30/90
Outputs
Of 79 Solanum spp, hybrids tested (1292 plants) in replicated field trials, there was a significant correlation of aphid resistance to PLRV resistance. About 8% (125) of these progeny identified as aphid resistant and tested for PLRV were crossed with advanced breeding material for future analysis. Analysis of 1989 field plots for PLRV was completed in May 1990. Proportion of plots with PLRV infection in Russet Burbank (a PLRV susceptible cultivar) was significantly higher than Kennebec (moderately resistant to PLRV) (59.3 vs. 25.0%, P<0.01). Within an infected plot the trend was for more Russet Burbank plants to be infected than Kennebec (4.1 vs. 2.2%, P>0.05). When under identical aphid pressure (188 vs. 224 aphid-days) Kennebec was more resistant to PLRV than Russet Burbank. Once, infected the proportion of tubers with PLRV was equal (67.5 and 65.0%). Average distance of virus spread was not significantly different between varieties (1.7 vs. 1.5 m). Cascade
(highly resistant to PLRV) was included with Russet Burbank and Kennebec in 1990 field trials. Green peach aphid longevity and reproductive period was not significantly different among these three cultivars (P<0.05). Aphid fecundity was significantly different being highest on Cascade (86.8 apterae), intermediate on Kennebec (76.9 apterae), and lowest on Russet Burbank (57.5 apterae) (P<0.05).
Impacts
(N/A)
Publications
- RAGSDALE, D.W., RADCLIFFE, E. B., DIFONZO, C.D., and BANTTARI, E. E. 1990. Action thresholds for an aphid vector of potato leafroll virus, In Potato integrated pest mgmt. in the north central U.S., accomplishments and priorities.
- FLANDERS, K.L., RAGSDALE, D.W. and RADCLIFFE, E.B. 1990. Use of enzyme linked immunosorbent assay to detect potato leafroll virus in field grown potato, c.v, Russet Burbank. Amer. Potato J. 67:589-602.
- FLANDERS, K.L., RAGSDALE, D.W. and RADCLIFFE, E.B. 1990. Spread of potato leafroll virus in relation to densities of GPA: implications for mgmt. thresholds for MN seed potatoes. In Proceedings: Aphid-plant interactions:populations to molec.
- FLANDERS, K.L., RADCLIFFE, E.B. and RAGSDALE, D.W. 1990. Potato leafroll virus spread in relation to densities of green peach aphid: implications for management thresholds for Minnesota seed potatoes. J. Econ. Entomol. 84: (In press).
- RADCLIFFE, E.B., RAGSDALE, D.W., and FLANDERS, K.L. 1990. Aphids and Leafhoppers: Economic Importance, Biology and Control. In APS Plant Health Management in Potato Production. (in-press).
- RADCLIFFE, E.B., FLANDERS, K.L. RAGSDALE, D.W. and NOETZEL, D.M. 1990. Potato Insects--Pest Management Systems for Potato Insects. In CRC Pest Management Series.
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Progress 01/01/89 to 12/30/89
Outputs
Using a split plot arrangement of treatments, experiments were designed that allowed us to test aphid action thresholds on spread of both potato leafroll virus (PLRV) and potato virus Y (PVY). We used two cultivars, Russet Burbank and Kennebec. Population gradients green peach aphids, Myzus persicae (Sulzer), were produced using selective insecticides. Target populations were 0,3,10,30 and 100 aphids per 100 leaves. Previous work demonstrated that 88% of the virus spread was accounted for in the center 3 rows so we concentrated our virus sampling effort on these rows. We harvested three tubers from each of 20 plants per row. We will sprout and serologically assay foliage from these tubers during the winter. Action thresholds were exceeded in five of the plots while in the remainder, aphid populations were maintained very near the prescribed action thresholds. We will analyze the data using linear regression of aphid-days to percent virus infection. These data will
allow us to critically examine the potential for both viruses to spread under low aphid population pressure. Sampling for overwintered green peach aphids at the Landscape Arboretum's Prunus collection did not yield any overwintered green peach aphids. In the late fall the Prunus collection at the research center was seeded with aphids which carry a genetic marker that will allow us to identify if any of these individuals survive the winter.
Impacts
(N/A)
Publications
- HANAFI, A., RADCLIFFE, E.B. and RAGSDALE, D.W. 1989. Spread and control of potato leafroll virus in Minnesota. J. Econ. Entomol. 82:1201-1206.
- FLANDERS, K.L. 1989. Green peach aphid (Homoptera:Aphididae) action thresholds for management of potato leafroll virus in potato. Ph.D. dissertation, Department of Entomology, University of Minnesota.
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Progress 01/01/88 to 12/30/88
Outputs
One spring migrant green peach aphid (GPA), M. persicae, was collected in pan traps at Rosemount Exper. Stn. indicating that GPA may overwinter here but in very small numbers. However, sampling Prunus americana at Rosemount provided no evidence that GPA overwintered. Field experiments conducted to determine if apterae- based thresholds (0, 10, 30, and 100/100 leaves) could be used to initiate aphid controls resulted in 2, 6.5, 9 and 13% potato leafroll virus (PLRV). Percent PLRV was highly correlated with GPA-days (r = 0.76). Caging viruliferous GPA on Russet Burbank at four different growth stages resulted in a decreasing number of infected tubers. Inoculating at early vegetative, late vegetative, tuber initiation, and tuber bulking resulted in 87, 70, 29 and 11% tuber infection, respectively. Field testing of the Acarapis woodi diagnostic test (enzyme linked immunosorbent assay - ELISA) was conducted. ELISA was more reliable and sensitive when frozen material
was used as compared to alcohol preserved material. Additional costs to collect and maintain frozen samples are offset by reducing required ELISA components, specifically bovine serum albumin, when using alcohol preserved material. No false positives were found in tests of 132 samples. ELISA is as accurate, reproducible, yet more cost effective than dissection. The principle advantage of ELISA over dissection is speed of processing samples. More than 3 times the number of samples could be processed by ELISA as compared to dissection.
Impacts
(N/A)
Publications
- HANAFI, A., RADCLIFFE, E.B. and RAGSDALE, D.W. 1988. Spread and control of potato leafroll virus in Minnesota. J. Econ. Entomol. (in-press).
- KJER, K.M., RAGSDALE, D.W. and FURGALA, B. 1984. A retrospective and prospective overview of the honey bee tracheal mite, Acarapis woodi R. Apidology (in-press).
- KJER, K.M. 1988. Diagnosis of tracheal mite (Acarapis woodi R.) parasitism of honey bees using monoclonal antibody based enzyme linked immunosorbent assay. M.S. thesis. Univer. Minn., St. Paul. 82 pp.
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