Source: NORTH CAROLINA STATE UNIV submitted to NRP
EXTENSION VEGETABLE PATHOLOGY WITH EMPHASIS ON CUCURBITS, SWEETPOTATOES, POSTHARVEST, FORECASTING AND COMMUNICATIONS TECHNOLOGY
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0212177
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jun 1, 2007
Project End Date
Sep 30, 2012
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
PLANT PATHOLOGY
Non Technical Summary
A. Several diseases of cucurbits and sweetpotatoes significantly reduce yield, quality and availability. B. Electronic communications provide new tools that can be used to develop, archive and rapidly disseminate training and expert knowledge. A. The purpose of these studies is to reduce losses from plant diseases by improving disease forecasting (timing of fungicide applications) and management practices by increasing our understanding of the biology of the causal agents. B. The purpose of using electronic communications is to provide high-quality and consistent training and to package expert and detailed information for efficient retrieval and usage.
Animal Health Component
70%
Research Effort Categories
Basic
15%
Applied
70%
Developmental
15%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2121429116050%
2121450116030%
2121499116020%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants;

Subject Of Investigation
1499 - Vegetables, general/other; 1450 - Sweet potato; 1429 - Cucurbits, other;

Field Of Science
1160 - Pathology;
Goals / Objectives
1. Cucurbit disease management (downy mildew and Phytophthora blight). 1.1 Since 1998, we have been forecasting the spread of cucurbit downy mildew (caused by Pseudoperonospora cubensis) using meteorological models that predict wind speed and direction (e.g., HYSPLIT). Currently we are focused on validation of the forecasting system. In addition, we are characterizing the pathogen with regards to host specialization (e.g., pathotypes) and fungicide resistance to strobilurin and acylanaline fungicides. 1.2 Research on Phytophthora blight is focused on fungicide efficacy, relative susceptibility of host plants and host tissues, and the effect of cultural systems on disease development. 2. Postharvest diseases of sweetpotato. The objective of my program is to understand the etiology and epidemiology of economically important postharvest diseases of sweetpotato. 2.1 I am co-PI in a multi-state (NC, LA, MS, AL), multi-disciplinary (plant pathology, entomology, weed science) project focused on preharvest factors affecting postharvest susceptibility to Rhizopus soft rot and Erwinia root rot. 2.2 Identification and characterization of Penicillium species found on sweetpotato. 2.3 Efficacy of postharvest treatments for control of Rhizopus soft rot. 3. Information and communication technology in extension. 3.1 Creating a national training program in crop biosecurity for first detectors. This is an online training program targeted at county agents and crop consultants nationwide. 3.2 Development of a database-driven management and retrieval system for extending IPM information to southeastern vegetable growers.
Project Methods
1.1 The accuracy and utility of a cucurbit downy mildew forecasting system is being evaluated by increasing the frequency of issued forecasts and comparing predictions of disease outbreaks with observed outbreaks. A network of over 40 cooperators in 19 states validate and report outbreaks in their respective locations. A system of sentinel plots also has been established to accurately determine the date of disease occurrence and to determine the pathotype/s involved. Multiple isolates of P. cubensis collected in many states are being screened for resistance to mefenoxam and azoxystrobin. Plants are treated with various concentrations of the fungicide followed by inoculation, incubation and evaluation of disease severity. Host specificity/pathotype is being determined by the compatibility of P. cubensis with a set of 12 differentials (i.e., cucurbit species). 1.2 Each year fungicides (timing and rates) are evaluated under field conditions for their efficacy against Phytophthora blight in cucurbits and solanaceous vegetable crops. Growing crops on bare ground, raised beds or with overhead irrigation is also being evaluated. 2.1 Thirty commercial fields of sweetpotatoes have been monitored annually for the past 3 years. Over 30 variables were measured (weather parameters, soil moisture and nutrient status, cropping history, cultural practices, etc.) and will be correlated to susceptibility of sweetpotato roots to Rhizopus soft rot and Erwinia root rot. 2.2 Over 100 isolates of Penicillium species have been collected from sweetpotato in NC. Each isolate is grown on several artificial media for characterization of growth rate, colony texture, color and micromorphology. These measurements will be used to identify each isolate to species. 2.3 Postharvest sweetpotato treatments are evaluated by dipping roots in suspensions of products under evaluation after inoculation with R. stolonifer. Each year several products are tested under different conditions (duration of dip treatment, concentration of active ingredient, method of treatment application, etc.) 3.1 A Content Management System (Lyra) and a Learning Management System (Moodle) were selected to create a training program in crop biosecurity for first detectors. Training materials were organized into 6 modules: Mission of the NPDN; Monitoring for high-risk pests, Diagnosing plant problems, Submitting plant samples, Photography for diagnostics, and Disease and pest scenarios. Each module is being developed in collaboration with the NPDN Training and Education committee and be reviewed by approximately 80 volunteer reviewers and beta testers. Training will be launched in Fall 2007. 3.2 In this project, we seek to develop a web-based information management and retrieval system for fungicide recommendations for vegetable crops in the Southeastern US. Pesticide label information will be archived, updated and retrieved using a custom database that integrates IPM strategies for disease control. While initially targeted at plant diseases control, the system will be applicable to insect and weed control.

Progress 06/01/07 to 09/30/12

Outputs
OUTPUTS: Many diseases affect vegetable crops grown in NC. This extension and research program primarily addressed diseases of cucurbits and sweetpotatoes and focused on reducing crop losses by reducing disease. It also included service to growers of many different vegetable crops grown in NC (e.g., crucifers, lettuce, potatoes, beans, onions, etc.) as well as the county agents who, in turn, served growers. Research results were published in nearly every form available from the peer-reviewed scientific paper to newsletters, both in print and on the Internet. A disease forecasting service for cucurbit downy mildew was developed in 1998 and continues to the present (Dec 2008). The Southeastern Vegetable Extension Workers (SEVEW) was formed in 1999. Each year this group meets to update vegetable production recommendations and publishes them in the yearly Southeastern Vegetable Handbook available in hard copy and on the Internet. Each year, 300-500 disease diagnoses and recommendations were provided to those submitting diseased specimens to the Plant Disease and Insect Clinic. Oral presentations were delivered in hundreds of venues across the United States and within NC to growers, extension educators, peer scientists and the general public. Through all of this, students and a postdoc received career training and advanced degrees and were able to quickly obtain gainful employment in closely related fields. PP500 was a 4-unit, graduate-level course developed for county agents and was taught spring semester of even-number years. PARTICIPANTS: Individuals who contributed significantly to this program include Wilfred Jester, Allan Thornton, and Jonathan Schultheis. These individuals are all faculty in the Horticultural Science Department at NCSU. Charles Averre who preceded me in this position was a tremendous mentor throughout. Other collaborators at NCSU are Mark Lancaster, Frank Louws, Kelly Ivors, and George Kennedy. Chris Clark at LSU was also a major contributor on sweetpotato projects. Many organizations supported the program with funding and other types of support. These include the NC Sweetpotato Commission, NC Vegetable Growers Association, NC Watermelon Association, Pickle Packers International, National Watermelon Association, Southern Region IPM Center, USDA CSREES, USDA National Research Initiative as well as state commodity boards in many eastern and mid-western states. Training and professional development was provided for graduate students and a postdoc as well as county agents on a regular basis. PP500 trained approximately 80 students and county agents in applied plant pathology through an intensive course. TARGET AUDIENCES: Target audiences included vegetable growers, the agents who served them and the commodity boards that represented them. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Outcomes from this program took the form of improved disease management practices. Perhaps the greatest impact was achieved with cucurbit downy mildew. This disease suddenly devastated the cucumber crop in NC and mid-Atlantic states in 2004. In 2005 it spread to Michigan, Ohio and Ontario, Canada and has been a serious problem each year since then. The forecasting system in place since 1998 had been temporarily suspended due to lack of funds, but was quickly revived to play a pivotal role in managing this new problem. Moreover, a disease management field trial was quickly put into place through the combined efforts of the principle investigator, a county agent (Allan Thornton) and a local grower. The trial was the first to directly address the new problem and provided clear results that provided the basis of effective control programs for the entire US. These efforts led to increased funding for the downy mildew forecasting system which is now one of five components of the ipmPIPE system. Other impacts in cucurbits include host range and disease management studies on the pathogen Phytophthora capsici that gave growers the best tools available and realistic expectations regarding management of this disease. Fungicide efficacy trials were conducted on powdery mildew of squash, lettuce drop, cucumber anthracnose, watermelon gummy stem blight, cantaloupe Alternaria blight and others. The results of these studies figured prominently in the national scene and often led to additional projects. Sweetpotato work focused primarily on postharvest diseases and the factors that influence susceptibility. Rhizopus soft rot was the main disease investigated, but Erwinia soft rot, scurf, soil rot, white rust, root knot, viruses, Fusarium surface rot and root rot were also studied. A large multi-state, multi-disciplinary project included an intensive survey of packinglines in NC and LA. It also measured dozens of field factors as they relate to the susceptibility of sweetpotatoes to decay by Rhizopus and Erwinia pathogens. The packingline survey has led many packinghouse managers to make significant changes to their packinglines in order to minimize injury to sweetpotatoes. The program was the leader in providing postharvest decay control recommendations in the US. Both conventional and biological products were evaluated. Export markets relied extensively on data generated from this program to justify the decay control measures taken. The Southeastern Vegetable Extension Workers met annually with participations from 12 states and over 40 extension specialists. The Vegetable Handbook was published annually and the number of printed copies increased each year to 6,500 for the 2009 edition. The publication was sponsored by the agricultural chemicals industry which paid all publication costs. Several research projects grew out of the collaboration and communication resulting from this important group and meeting. It has never been stronger than it is today (Dec 2008). PP500 attracted 10-20 students each time it was taught. Student evaluations were consistently very high (4.8/5.0).

Publications

  • BOOK CHAPTER: Clark, C. A., Holmes, G. J., and Ferrin, D. M. 2008 Major Fungal and Bacterial Diseases. Chapt. 10 in: The Sweet Potato, G. Loebenstein, ed., Springer. In press.
  • PLANT DISEASE MANAGEMENT REPORTS: Edmunds, B.A. and Holmes, G.J. 2008. Susceptibility of sweetpotato tablestock and high dry matter cultigens to Rhizopus soft rot, 2005. Plant Disease Management Reports (online). Report 2:V146. DOI:10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • PEER REVIEWED: Yencho, G.C., Pecota, K.V., Schultheis, J.R., Pesic-VanEsbroeck, Z., Holmes, G.J., Little, B.E., Thornton, A.C. and Truong, V. 2008. Covington Sweetpotato. HORTSCIENCE 43(6):1911-1914.
  • Edmunds, B.A. and Holmes, G.J. 2008. Evaluation of alternative decay control products for control of postharvest Rhizopus soft rot of sweetpotatoes. Plant Health Progress. In press.
  • EXTENSION BULLETIN: Edmunds, B.A., Boyette, M.D., Clark, C.A., Ferrin, D.M., Smith, T.P. and Holmes, G.J. 2008. Postharvest handling of sweetpotatoes. NC State University publication AG-413-10-B. 56 pp.
  • Southeastern U.S. 2008 Vegetable Crop Handbook. G.J. Holmes and J.M. Kemble, eds. Southeastern Vegetable Extension Workers. 260 pp. 6,200 copies printed
  • M. L. Adams, G. J. Holmes, and A.C. Thornton. 2008. Evaluation of fungicides for control of downy mildew of cabbage, Sampson County 2007. Plant Disease Management Reports (online). Report 2:V119. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams and G. J. Holmes . 2008. Evaluation of fungicides for control of downy mildew of cucumber and winter squash, Clayton 2007. Plant Disease Management Reports, (online). Report 2:V114. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams and G. J. Holmes. 2008. Evaluation of fungicides for control of powdery mildew of winter squash, Fletcher 2007. Plant Disease Management Reports, (online). Report 2:V115. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams and G. J. Holmes. 2008. Evaluation of fungicides for control of downy mildew and powdery mildew of winter squash, Kinston 2007. Plant Disease Management Reports, (online). Report 2:V113. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams, G. J. Holmes, and A.C. Thornton. 2008. Evaluation of fungicides for control of downy mildew of watermelon, 2007. Plant Disease Management Reports, (online). Report 2:V117. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams, G. J. Holmes, and W.R. Jester. 2008. Evaluation of cultural practices and fungicides for control of Phytophthora blight of watermelon, 2007. Plant Disease Management Reports, (online). Report 2:V116. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • M. L. Adams, G. J. Holmes, and K.L. Ivors. 2008. Evaluation of fungicides for control of Phytophthora blight of summer squash, Fletcher 2007. Plant Disease Management Reports, (online). Report 2:V118. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • S.J. Colucci, A.C. Thornton, M.L. Adams and G.J. HolmeS. 2008. Evaluation of fungicides for control of downy mildew of cucumber I, 2007. Plant Disease Management Reports, (online). Report 2:V043. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • S.J. Colucci, A.C. Thornton, M.L. Adams and G.J. Holmes. 2008. Delayed fungicide application to cucumber and the effects of downy mildew severity and yield I, 2007. Plant Disease Management Reports, (online). Report 2:V044. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • S.J. Colucci, A.C. Thornton, M.L. Adams and G.J. Holmes. 2008. Evaluation of fungicides for control of downy mildew of cucumber II, 2007. Plant Disease Management Reports, (online). Report 2:V045. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • S.J. Colucci, A.C. Thornton, M.L. Adams and G.J. Holmes. 2008. Delayed fungicide application to cucumber and the effects of downy mildew severity and yield II, 2007. Plant Disease Management Reports, (online). Report 2:V046. DOI: 10.1094/PDMR02. The American Phytopathological Society, St. Paul, MN.
  • RESEARCH ABSTRACTS: Adams, M.L., Kousik, C.S. and Holmes, G.J. 2008. Evaluation of fungicides for control of Phytophthora blight of watermelon in North Carolina and South Carolina. Phytopathology 98:S10.
  • Holmes, G.J., Edmunds, B.A. and Colucci, S.J. 2008. Using wikis to communicate plant pathology information. Phytopathology 98:S68.
  • Edmunds, B.A. and Holmes, G.J. 2008. The effect of packingline impacts on susceptibility of sweetpotatoes (Ipomoea batatas) to Rhizopus stolonifer. Phytopathology 98:S49.
  • Edmunds, B.A, Clark, C.A., Holmes, G.J., and Gray, E.D. 2008. Relationships between Preharvest Conditions and Increased Susceptibility of Sweetpotatoes to Rhizopus and Bacterial Soft Rots in Louisiana and North Carolina. HortScience 43(3):619.
  • NC PEST NEWS: Holmes, G.J. 2008. Agrian.com: A Free, Comprehensive, Searchable Pesticide Label Database, and More. North Carolina Pest News 23(13) July 3, 2008
  • Holmes, G.J. and Louws, F.J. 2008. First Report of Cucumber Downy Mildew for North Carolina in 2008. North Carolina Pest News 23(14) July 11, 2008
  • Edmunds, B.J. and Holmes, G.J. 2008. Potato late blight outbreak in Camden county. NC Pest News 23(8): May 30, 2008 http://ipm.ncsu.edu/current_ipm/08PestNews/08News8/pestnews.html#titl e3
  • Holmes, G., Ivors, K and Louws, F. 2008. New fungicides for vegetables in 2008. North Carolina Pest News 23(1), April 11.
  • EXTENSION FACT SHEETS: Louws, F.J., Holmes, G.J. and Ivors, K.L. 2008. Cucurbits - Phytophthora blight. http://www.cals.ncsu.edu/plantpath/extension/fact_sheets/Cucurbits_-_ Phytophthora_blight.htm. May 20.
  • Ye, W., Barker, K, Holmes, G., Pecota, K. and Yencho, C. 2008. Nematodes on sweetpotato. Nema Note 14. NCDA Nema Note Series. www.ncagr.com/agronomi/uyrnem.htm