Progress 10/01/11 to 09/30/16
Outputs
Target Audience:The target audience for information produced by this project is the commercial lowbush blueberry growers and field managers of Maine, NH and Massachusetts, the general public living near blueberry fields, growing patches of blueberries, or interested in blueberries, and fellow researchers on blueberries. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One graduate student, since graduated in Dec. 2015, studied the population genetics of Valdensia heterodoxa and has been trained in steriletechniques, isolation and maintenance of fungi, DNA extraction and DNA amplification techniques, statistics and population genetic analysis and GIS statistics. Another graduate student has been trained in sterile techniques, isolation and maintenance of fungi, and experimental design and statistics. Eleven undergraduate students have been trained in various lab and field techniques throughout the duration of the project. Four research assistants have been trained in blueberry field research, lab techniques to work with fungi, and statistics. How have the results been disseminated to communities of interest?Each year of the project, information on results of the objectives have been presented to blueberry growers and the general public in blog posts at umaine.edu/blueberries/blog/ website and via an email mailing list and answering machine messages during the season. Presentations were made on results of studies to Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April and May and to growers at the Wild Blueberry field day in July. Results were also presented to growers as talks and in written reports at the Wild Blueberry Commission meeting each fall and early winter. Research results were presented in talks to growers and fellow blueberry disease researchers at Wild Blueberry research and Extension workers meetings and at scientific meetings of the American Phytopathological Society, Mycological Society of America, Botany 2015 meeting by the lead researcher, graduate students and research assistants. One peer-reviewed journal articles has been published and once has been accepted. Two manuscripts are in the process of being submitted and three are in preparation. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Lowbush (wild) blueberries are an important and unique commercial crop to the state of Maine. Lowbush blueberry growers are increasingly under both economic and public pressure to efficiently manage their inputs to control diseases. We studied a variety of diseases that affect lowbush blueberry to better understand their biology and develop improved methods of control. We DNA fingerprinted isolates of the fungus causing Valdensia leaf spot from fields in Maine and northeastern Canada and found isolates were very similar to one another. We also found most outbreaks of the disease were at field entrances and near roads suggesting that isolates are being transported by field equipment. This has led growers to be more careful in their movement of field equipment and to wash equipment before it is transported. We found variation in the levels of leaf spots and stem blights between different management systems that may be due to different levels of inputs. Use of fungicides and maybe fertility treatments have an impact on disease levels and this is currently under further study. We have identified a decrease in sensitivity to propiconazole among isolates of the fungus causing mummy berry in fields where that fungicide had been used for years. We have identified fungicides with different modes of action than propiconazole that can effectively control mummy berry and some growers are starting to use them. We have found that the number of chilling hours, soil temperature and moisture affect the production of inoculum by the mummy berry fungus. We are developing a model of inoculum production to better time fungicide application for control of mummy berry in the future. This research has increased knowledge of the key diseases affecting lowbush blueberry and growers have changed their practices to improve control of these diseases. Obj. 1: Study the biology and control of Valdensia leaf spot of lowbush blueberries. 1a). Thirty four Maine locations were identified with Valdensia leaf spot from 2009 to 2015 and Valdensia was found to occur as varying sized patches, often under shade or near the roads into fields. Erika Lyon, MS graduate student, did a comparison of landscape features between 27 Valdensia sites located in lowbush blueberry fields to 84 random locations in blueberry fields. The only landscape features that are significantly found to occur more commonly with Valdensia leaf spot locations are nearness to roads, field entrances and field edges. 1b) We were unable to find a suitable field to test control of Valdensia in the field, we did try a variety of biological controls in lab experiments with mixed results. 1c) In total, 185 isolates from fields in Maine, Nova Scotia and Prince Edward Island have been genotyped with seven microsatellite markers identified from 35 putative microsatellite primer pairs provided by James Polashock, USDA- ARS. Analysis of the microsatellite data found low genetic diversity within and between sampled fields and that populations in Maine and Canada were also genetically similar to one another. Many of the fields contained a single multilocus haplotype, and many fields, from all regions, shared a single multilocus haplotype, suggesting that there is primarily clonal reproduction. There were significant differences among fields managed by different entities. These data suggest the populations in Maine and Canada are similar and that there has been spread from one field to the next in Maine probably on contaminated field equipment. Obj.2: Examine the effects of management techniques on fungal diseases of lowbush blueberries. The management system study examining low, medium, high and organic inputs for blueberry management has been looking at a variety of fields for three crop cycles (2 years each; 2010 to 2015). Field surveys found significant differences in blueberry cover, leaf loss and some diseases among management systems. Blueberry cover has been consistent over the 6 years with the lowest levels in organic and low input fields and higher levels in medium and high input fields. No differences were found among the fields for mummy berry which is probably from variation in inoculum levels and control tactics. Some leaf spots, Septoria leaf spot and leaf rust, were more common in low and organic input fields, but Phomopsis stem blight was found at higher levels typically in medium and higher input fields. Mulch had no effect on disease levels in the one crop cycle it was applied. Preliminary analysis suggested factors associated with higher fertility were also associated with higher levels of Phomopsis. Leaf loss was inconsistent among the years but higher levels of leaf rust were correlated with higher levels of leaf loss in the prune year.Obj. 3: Study the biology of Monilinia vaccinii-corymbosi (MVC) and control of mummy berry. In fungicide trials over the last 5 years, in two fields each year, we have tested fungicides with different chemistries, biological control materials, and mixtures of fungicides to find alternatives to the most commonly used fungicide, propiconazole. We have found one fungicide with a different chemistry and one with a different azole ingredient which had significantly less mummy berry disease compared to untreated controls. These data have provided new materials to use for control of this disease. Growers at field meetings answered questions about mummy berry disease correctly over 75% of the time, and consistently 67% of surveyed growers are using the mummy berry forecasting method using internet connected weather stations and grower monitored pseudosclerotia plots. To look at MVC pseudosclerotia germination and apothecia longevity, common garden field experiments have been set up for the last 5 years and lab experiment for the last 4 years with pseudosclerotia from four to five different blueberry fields. We have had mixed results with both lab and field experiments. Field experiments have been affected by drought, flooding, and loss of MVC pseudosclerotia to an unknown cause. We have determined pseudosclerotia require a "maturing" process in the fall before a chilling period and then warmer conditions for germination. Freeze/thaw cycles in the lab, prolonged storage at room temperature or at 4 C and water content of the soil also can decrease germination. Tyler Case, a MS graduate student has found pseudosclerotia require at least 900 chill hours before germination and that longer chill hours require less post-chill hours for germination. Apothecia can persist from 2 to 4 days and many pseudosclerotia start germination but do not produce apothecia. Soil temperature and moisture strongly affect germination with warmer temperatures producing higher levels of germination. Experiments have demonstrated insects also consume or damage pseudosclerotia in the field. There may also be fungi and bacteria involved in the breakdown of pseudosclerotia, and over 40 fungal and 50 bacterial isolates have been isolated from surface-sterilized pseudosclerotia. Over 40 fungal isolates have been preliminarily screened for antagonism to MVC hyphae. Obj. 4: Studies on emerging diseases in lowbush blueberry. We have identified 3 new fields with an early dieback of prune plants. We have identified Phytophthora cactorum as a potential pathogen consistently isolated from infected roots. Fungal inoculations on potted plants have demonstrated some effects on roots. We have also identified the fungal fruit spot disease Exobasidium on lowbush blueberry.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Factors affecting germination of pseudosclerotia of Monilinia vaccinii-corymbosi on lowbush blueberry. http://www.apsnet.org/meetings/Documents/2016_meeting_abstracts/aps2016_330.htm
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Annis. S., F. Drummond, R. Martin, T. Case, E. Ballman, and E. Venturini. 2016. Update on Mummy Berry Disease. WILDBREW. Fredericton, NB, Oct. 19 to 21, 2016.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Martin, R. and S. Annis. 2016. Using spore traps to track disease. WILDBREW. Fredericton, NB, Oct. 19 to 21, 2016.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2015
Citation:
Lyon, Erika, "Dispersal and Establishment of the Fungal Pathogen, Valdensia heterodoxa, in Maine" (2015). Electronic Theses and Dissertations. 2382.
http://digitalcommons.library.umaine.edu/etd/2382
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2012
Citation:
Thompson, Ashley A., "An Assessment of the Variation in Populations of Monilinia Vaccinii-Corymbosi in Lowbush Blueberry in Maine" (2012). Electronic Theses and Dissertations. 1837.
http://digitalcommons.library.umaine.edu/etd/1837
|
Progress 10/01/14 to 09/30/15
Outputs
Target Audience:The target audience for information produced by this project is the commercial lowbush blueberry growers and field managers of Maine, NH and Mass., the general public living near blueberry fields, growing patches of blueberries, or interested in blueberries, and fellow researchers on blueberries. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One graduate student is working on the population genetics of Valdensinia heterodoxa and has been trained in sterile techniques, isolation and maintenance of fungi, DNA extraction and DNA amplification techniques, statistics and population genetic analysis and GIS statistics. Another graduate student has been trained in sterile techniques, isolation and maintenance of fungi, and experimental design. Five undergraduate students have been trained in various lab and field techniques. A research assistant been trained in blueberry field research and statistics. How have the results been disseminated to communities of interest?Information on results of the objectives have been presented to blueberry growers and the general public in blog posts at umaine.edu/blueberries/blog/ website and via an email mailing list and answering machine messages during the season. Presentations were made on results of studies to Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April and May and to growers at the Wild Blueberry field day in July. Results were also presented to growers at the Wild Blueberry Commission meeting and growers and fellow blueberry disease researchers at the WILDBREW meeting Bar Harbor, ME and other researchers at the Botany 2015 conference and Maple syrup conference. What do you plan to do during the next reporting period to accomplish the goals?Continue on current path to complete goals by Sept. 2016.
Impacts
What was accomplished under these goals?
Obj. 1: Study the biology and control of Valdensia leaf spot of lowbush blueberries. 1a). Thirty four Maine locations were identified with Valdensia leaf spot from 2009 to 2015 and Valdensia was found to occur as varying sized patches, often under shade or near the roads into fields. Erika Lyon, MS graduate student, did a comparison of landscape features between 27 Valdensia sites located in lowbush blueberry fields to 84 random locations in blueberry fields. The only landscape features that are significantly found to occur more commonly with Valdensia leaf spot locations are nearness to roads, field entrances and field edges. 1c) In total, 185 isolates from fields in Maine, Nova Scotia and Prince Edward Island have been genotyped with seven microsatellite markers identified from 35 putative microsatellite primer pairs provided by James Polashock, USDA-ARS. Analysis of the microsatellite data found low genetic diversity within and between sampled fields and that populations in Maine and Canada were also genetically similar to one another. Many of the fields contained a single multilocus haplotype, and many fields, from all regions, shared a single multilocus haplotype, suggesting that there is primarily clonal reproduction. There were significant differences among fields managed by different entities. These data suggest the populations in Maine and Canada are similar and that there has been spread from one field to the next in Maine probably on contaminated field equipment. Obj.2: Examine the effects of management techniques on fungal diseases of lowbush blueberries. The management system study examining low, medium, high and organic inputs for blueberry management has been looking at a variety of fields for three crop cycles (2 years each; 2010 to 2015). Field surveys found significant differences in blueberry cover, leaf loss and some diseases among management systems. Blueberry cover has been consistent over the 6 years with the lowest levels in organic and low input fields and higher levels in medium and high input fields. No differences were found among the fields for mummy berry which is probably from variation in inoculum levels and control tactics. Some leaf spots, Septoria leaf spot and leaf rust, were more common in low and organic input fields, but Phomopsis stem blight was found at higher levels typically in medium and higher input fields. Mulch had no effect on disease levels in the one crop cycle it was applied. Preliminary analysis suggested factors associated with higher fertility were also associated with higher levels of Phomopsis. Leaf loss was inconsistent among the years but higher levels of leaf rust were correlated with higher levels of leaf loss in the prune year. Analysis is continuing on 2015 data and factors that may be affecting disease levels. Obj. 3: Study the biology of Monilinia vaccinii-corymbosi (MVC) and control of mummy berry. In fungicide trials over the last 4 years, in two fields each year, we have tested fungicides with different chemistries, biological control materials, and mixtures of fungicides to find alternatives to the most commonly used fungicide, propiconazole. We have found one fungicide with a different chemistry and one with a different azole ingredient which had significantly less mummy berry disease compared to untreated controls. These data have provided new materials to use for control of this disease. Growers at field meetings answered questions about mummy berry disease correctly over 75% of the time, and consistently 67% of surveyed growers are using the mummy berry forecasting method using internet connected weather stations and grower monitored pseudosclerotia plots. To look at MVC pseudosclerotia germination and apothecia longevity, common garden field experiments have been set up for the last 4 years and lab experiment for the last 3 years with pseudosclerotia from four to five different blueberry fields. We have had mixed results with both lab and field experiments. Field experiments have been affected by drought, flooding, and loss of MVC pseudosclerotia to an unknown cause. We have determined pseudosclerotia require a "maturing" process in the fall before a chilling period and then warmer conditions for germination. Freeze/thaw cycles in the lab, prolonged storage at room temperature or at 4 C and water content of the soil also can decrease germination. Since July 2014, Tyler Case, MS graduate student, has been working on this project. From the last two years of lab experiments, we have found pseudosclerotia require at least 900 chill hours before germination and that longer chill hours require less post-chill hours for germination. Apothecia can persist from 2 to 4 days and many pseudosclerotia start germination but do not produce apothecia. Field and lab experiments have been set up again this fall and more years of study may be required. Preliminary experiments to determine if there are insect fungivores eating pseudosclerotia are being conducted. There may also be fungi and bacteria involved in the breakdown of pseudosclerotia, and over 40 fungal and 50 bacterial isolates have been isolated from surface-sterilized pseudosclerotia. Over 40 fungal isolates have been preliminarily screened for antagonism to MVC hyphae. Tests of isolated bacteria will be completed in 2016. Obj. 4: Studies on emerging diseases in lowbush blueberry. We have identified 3 new fields with an early dieback of prune plants. We have identified Phytophthora cactorum as a potential pathogen consistently isolated from infected roots. Fungal inoculations on potted plants have demonstrated some effects on roots and will be repeated. Preliminary control trials in prune fields with prior symptoms of the disease will be done in spring 2016.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2015
Citation:
Lyon, E., Polashock, J., Hildebrand, P.D., Annis, S.L. 2015. Population genetic structure and spread of Valdensinia heterodoxa, an emergent plant pathogen in Maine and Eastern Canada. Botany 2015 meeting. Edmonton, AL, Canada. July 25-29, 2015.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2015
Citation:
Annis, S. L., Case, T. 2015. Factors affecting the germination of pseudosclerotia of Monilinia vaccinii-corymbosi. Botany 2015 meeting. Edmonton, AL, Canada. July 25-29, 2015.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Annis, S.L., Hopkins, K., Calder, B. and Perkins, B. 2014. Fungi contaminating bottled maple syrup. Abstract. Mycological Society of America, Inoculum 65(3), June 2014 page. 19
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2015
Citation:
Annis, S.L and T. Case. 2015. Factors affecting the overwintering and germination of pseudosclerotia of Monilinia vaccinii-corymbosi. WILDBREW. Bar Harbor, ME. Oct. 22, 2015
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2015
Citation:
T. Case, S.L. Annis and F. Drummond. 2015. Are ground dwelling insects consuming mummy berries during the overwintering process? WILDBREW. Bar Harbor, ME. Oct. 22, 2015
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Annis, S.L., Hopkins, K., Calder, B. and Perkins, B. 2014. Fungi contaminating bottled maple syrup. North American Maple Syrup council meeting. Wolfville, NS, Canada. Oct. 23 to Oct 25, 2013.
|
Progress 10/01/13 to 09/30/14
Outputs
Target Audience: The target audience for information produced by this project is the commercial lowbush blueberry growers and field managers of Maine, NH and Mass., the general public living near blueberry fields, growing patches of blueberries, or interested in blueberries, and fellow researchers on blueberries. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One graduate student is working on the population genetics of Valdensinia heterodoxa and has been trained in sterile techniques, isolation and maintenance of fungi, DNA extraction and DNA amplification techniques. Another graduate student has been trained in sterile techniques, isolation and maintenance of fungi, and experimental design. Four undergraduate students have been trained in various lab and field techniques. A research assistant was trained on maintenance of fungi and statistical methods and another has been trained in blueberry field research. How have the results been disseminated to communities of interest? Information on results of the objectives have been presented to blueberry growers and the general public in blog posts at umaine.edu/blueberries/blog/ website and via an email mailing list and answering machine messages during the season. Presentations were made on results of studies to Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April, May, and June and at an organic grower meeting in June and to growers at the Wild Blueberry field day in July. Results were also presented to growers at the Wild Blueberry Commission meeting and growers and fellow blueberry disease researchers at the NABREW meeting in Atlantic City, NJ in June. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Over the last decade, the lowbush blueberry industry in Maine has come under pressure to decrease inputs, such as fungicides, that may impact the environment and at the same time, the number of fungal diseases affecting the crop has increased. Development of effective integrated pest management strategies for the most damaging fungal diseases to lowbush blueberry will improve the productivity of the blueberry industry. One of the potentially most damaging diseases is Valdensinia leaf spot which has only recently been found in Maine. This research will increase our knowledge of how this disease spreads among fields and will develop control strategies for this disease, as well as, study the genetic diversity of this fungus. Blueberry growers have increased their knowledge of Valdensinia leaf spot and are becoming aware that they will need to change their practices to control the spread of this disease. Mummy berry disease is the most widespread, damaging disease of lowbush blueberry and the disease that most fungicides are applied to control. The fungicide, propiconazole, is widely used to control this disease and has been used for many years. We have found there is a significant decrease in sensitivity to propiconazole in isolates from fields treated with this fungicide compared to isolates from an area never treated with fungicides. Continued use of only propiconazole may increase the risk of the fungus developing resistance to this fungicide over time. We have tested numerous fungicides and have found ones with different modes of action (mechanisms of disrupting fungi) that are effective in controlling mummy berry disease. Growers are now starting to use fungicides with different modes of action. Lowbush blueberry growers vary in their management practices and range from few inputs, such as only pruning, to intensive management with inputs of fertilizer, pesticides, irrigation, and pollinators. Organic growers also vary in their inputs compared to those using conventional pesticides. We have found higher levels of leaf spot diseases in organic and lower input fields but higher levels of some stem diseases in medium and higher input fields. We are examining which management practices may be related to these differences in disease levels. We have found increased reports of root rot disease in blueberry fields and have isolated organisms that may be causing this disease. We are in the process of identifying the disease causal organism which will lead to methods of controlling this problem. The information obtained during this project will increase productivity of lowbush blueberry fields by improving control of diseases affecting the crop. Obj. 1: Study the biology and control of Valdensinia leaf spot of lowbush blueberries. GIS landscape analysis is continuing as new fields were identified with Valdensinia leaf spot. We are examining the landscape features for 27 locations where Valdensinia has been found in the last 5 years in Maine. Multiple fungal isolates have been collected in the majority of these locations. We have collected new isolates of the fungus and have 167 isolates from Maine fields and DNA from 55 isolates from the Maritime provinces. We obtained putative microsatellite primer sequences from James Polashock and have tested 37 pairs and have 9 pairs that look promising for genetic work. The microsatellite analysis of all of the Canadian and US isolates will be conducted in 2015. Preliminary experiments have been performed to develop the method of inoculating detached leaves to study the variation in disease development among different blueberry clones. The inoculation experiments will be conducted in 2015. In 2013, a large field was identified with Valdensinia leaf spot disease but the grower decided to apply fungicides and so we were unable to use this area for a control trial. We have been encouraging growers to burn the above-ground plants and leaf litter to eradicate the fungus and most growers who identify small disease patches have been doing so. We were again unable to find a field with a large enough area of this disease to conduct a field control trial. I am discussions with some growers about using their fields in the 2015 season. Obj.2: Examine the effects of management techniques on fungal diseases of lowbush blueberries. The management system study examining low, medium, high and organic inputs for blueberry management was extended for another two year crop cycle. To accommodate growers who were no longer interested in the project and to expand the geographic range of field, seven new fields were used to replace other fields used for the last 4 years. Field surveys were made in September of 2014 of blueberry cover, leaf loss, and percent cover of fungal stem (Phomopsis) and leaf spot (leaf rust, powdery mildew, Septoria) diseases in the organic, low, medium and high input management systems. Blueberry cover has been similar in all 5 years with lowest levels in organic and low input fields and higher levels in medium and high input fields. Leaf loss has varied amongst the systems each year and may be related to levels of combinations or individual levels of leaf spot diseases, such as Septoria leaf spot and leaf rust. Significantly higher levels of stem blight have been found in the high input fields compared to the other inputs in the last four years. Preliminary studies suggest these high levels may be correlated to measures of plant fertility and may be affected by fertilizer treatments. Obj. 3: Study the biology and control of mummy berry disease. We conducted fungicide field trials to test new fungicides for control of mummy berry disease and have found ones with either different modes of action or different chemistries that are effective in controlling mummy berry disease. We have set up a second field common garden experiment with pseudosclerotia from 4 different blueberry fields to determine if there are inherent differences in when the apothecia develop and the weather factors that affect apothecia development and longevity. We did not see any differences in germination amongst original field locations, but did have low levels of germination. Many initial early stage structures do not develop into apothecia, and many stages can persist for multiple days before further development. We also discovered that there are organisms that are ingesting or breaking down the pseudosclerotia in the fall and we will run experiments to determine the organisms involved. We also set up an in vitro germination experiment and found that less than 1000 chill hours produces mostly stalks with little further development to apothecia. With increasing chill hours we had increasing numbers of apothecia produced. This experiment is being repeated with pseudosclerotia from more fields. Plots were set up in growers' fields in 2013 and used to monitor development of apothecia for a mummy berry forecast system in 2014. Obj. 4: Studies on emerging diseases in lowbush blueberry. We have identified 3 new fields with an early dieback of prune plants. We have identified Phytophthora cactorum as a potential pathogen consistently isolated from infected roots. Fungal inoculations on potted plants have demonstrated some effects on roots and will be repeated. New symptoms including a scorch of plants and yellowing of leaves of some plants are being investigated.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Thompson, A. A., and Annis, S. L. 2014. Fungicide sensitivity assessed in Monilinia vaccinii-corymbosi isolates from lowbush blueberry fields in Maine.
Plant Health Progress doi:10.1094/PHP-RS-13-0127.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Annis, S.L. 2014. Improved management of Monilinia vaccinii-corymbosi in lowbush blueberry in Maine. North American Blueberry Research and Extension Workers meeting, June 23 to 27, 2014, Atlantic City, NJ.
|
Progress 10/01/12 to 09/30/13
Outputs
Target Audience: The target audience for information produced by this project is the commercial lowbush blueberry growers and field managers of Maine, NH and Mass., the general public living near blueberry fields, growing patches of blueberries, or interested in blueberries, and fellow researchers of blueberries. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One graduate student. Erika Lyon, is working on the population genetics of Valdensinia heterodoxa and has been trained in sterile techniques, isolation and maintenance of fungi, DNA extraction and DNA amplification techniques. Four undergraduate students have been trained in various lab and field techniques. How have the results been disseminated to communities of interest? Information on results of the objectives have been presented to blueberry growers and the general public in blog posts on the www.wildblueberries.maine.edu website and via email mailing list and answering machine messages during the season. Presentations were made on results of studies to Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April, May, and June and at an organic grower meeting in June, to growers at the Wild Blueberry field day in July each year. Results were also presented to growers at the Wild Blueberry Commission meeting and growers and fellow blueberry disease researchers at the APS meeting in August in Austin, TX, and the WildBrew meeting in Bangor, ME in Oct. 2013. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Over the last decade, the lowbush blueberry industry in Maine has come under pressure to decrease inputs, such as fungicides, that may impact the environment and at the same time, the number of fungal diseases affecting the crop has increased. Development of effective integrated pest management strategies for the most damaging fungal diseases to lowbush blueberry will improve the productivity of the blueberry industry. One of the potentially most damaging diseases is Valdensinia leaf spot which has only recently been found in Maine. This research will increase our knowledge of how this disease spreads among fields and will develop control strategies for this disease, as well as, study the genetic diversity of this fungus. Blueberry growers have increased their knowledge of Valdensinia leaf spot and are becoming aware that they will need to change their practices to control the spread of this disease. Mummy berry disease is the most widespread, damaging disease of lowbush blueberry and the disease that most fungicides are applied to control. The fungicide, propiconazole, is widely used to control this disease and has been used for many years. We have found there is a significant decrease in sensitivity to propiconazole in isolates from fields treated with this fungicide compared to isolates from an area never treated with fungicides. Continued use of only propiconazole may increase the risk of the fungus developing resistance to this fungicide over time. We have tested numerous fungicides and have found ones with different modes of action (mechanisms of disrupting fungi) that are effective in controlling mummy berry disease. Growers are now starting to use fungicides with different modes of action. Lowbush blueberry growers vary in their management practices and range from few inputs, such as only pruning, to intensive management with inputs of fertilizer, pesticides, irrigation, and pollinators. Organic growers also vary in their inputs compared to those using conventional pesticides. We have found higher levels of leaf spot diseases in organic and lower input fields but higher levels of some stem diseases in medium and higher input fields. We are examining which management practices may be related to these differences in disease levels. We have found increased reports of root rot disease in blueberry fields and have isolated organisms that may be causing this disease. We are in the process of identifying the disease causal organism which will lead to methods of controlling this problem. The information obtained during this project will increase productivity of lowbush blueberry fields by improving control of diseases affecting the crop. Obj. 1: Study the biology and control of Valdensinia leaf spot of lowbush blueberries. A preliminary GIS landscape analysis was conducting on the sites with Valdensinia but no landscape features were identified as correlating with presences of the disease possibly due to our low sample size of 15 fields. Valdensinia leaf spot was identified in four new blueberry fields and these sites will be added to the GIS analysis. New disease sites and some fields previously identified with the disease were visited, disease locations were GPS marked, and samples were taken to isolate the fungus. We have collected new isolates of the fungus and have 148 isolates from Maine fields and DNA from 55 isolates from the Maritime provinces. DNA has been extracted from the majority of the Maine isolates and we are testing microsatellite primers identified by James Polashock. We were again unable to find a field with a large enough area of this disease to conduct a field control trial. Some of the fields identified this year may be large enough to conduct a trial next year. Obj.2: Examine the effects of management techniques on fungal diseases of lowbush blueberries. Field surveys were made in June and September in 2013 of blueberry cover, leaf loss, mummy berry severity and incidence, and percent cover of fungal stem (Phomopsis, red leaf) and leaf spot (leaf rust, powdery mildew, Septoria, false Valdensinia) diseases in the organic, low, medium and high input management systems. We found no effect of management type on mummy berry disease, powdery mildew and minor leaf spot diseases. There was a significant higher levels of leaf loss in the high input fields compared to medium and low input and the lowest level of leaf loss was in the organic fields. The leaf loss did not correlate with higher levels of leaf spot diseases. The highest levels of Septoria were in the low and organic input fields and the levels of leaf rust were highest in the low and high input field. The level of Phomopsis blight was significantly higher in the medium and high input fields for the last 3 years. We are in the process of looking for which management practices may be affecting these diseases. Obj. 3: Study the biology and control of mummy berry disease. We have found there is a significant decrease in sensitivity to propiconazole, but not fenbuconazole, in isolates from fields treated with this fungicide compared to isolates from an area never treated with fungicides. Continued use of only propiconazole may increase the risk of the fungus developing resistance to this fungicide over time. We conducted fungicide field trials to test new fungicides for control of mummy berry disease and have found ones with either different modes of action or different chemistries that are effective in controlling mummy berry disease. We have set up a field common garden experiment with pseudosclerotia from 4 different locations to determine if there are inherent differences in when the apothecia develop and the weather factors that affect apothecia development and longevity. We had dry weather and so had low levels of germination of pseudosclerotia. We did not find any differences in pseudosclerotia collected from different locations in this trial. We have set up a lab experiment to look at the effects of chill hours and growing degree days on the development of pseudosclerotia from different locations. We also have set up plots in growers' fields to monitor development of apothecia for a mummy berry forecast system. In 2013, we provided reports on mummy berry infection as blog posts, answering machine messages and email alerts from April to May, and then subsequent posts on other diseases. Obj. 4: Studies on emerging diseases in lowbush blueberry. We have identified 2 new fields with an early dieback of prune plants. Multiple fungi were isolated from symptomatic roots and rhizomes and fungal inoculations are being performed on potted plants to determine the causal agent. We have a putative causal agent and are in the process of replicating inoculation experiments.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Annis, S.; Slemmons, C. R. 2013 Effects of management systems on stem and leaf spot diseases in lowbush blueberry. Abstract. Phytopathology. 103(6) Suppl. 2:7-8
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Annis, S. L.; Slemmons, C. R.; Hildebrand, P. D, R. Delbridge. 2013 An Internet-served forecast system for mummy berry disease in Maine lowbush blueberry fields using weather stations with cellular telemetry. Abstract. Phytopathology 103(6) Suppl. 2:8
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2013
Citation:
S. L. Annis, C. Slemmons and T. Levitsky. 2013. Observations on disease among management systems for lowbush blueberries 2 crop cycles. WILDBREW, Bangor, ME. October 24, 2013.
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Obj. 1:Study the biology and control of Valdensinia leaf spot of lowbush blueberries. Information sheets on disease symptoms were distributed to growers via the web and at twilight scouting meetings. Valdensinia leaf spot was identified at one new site in a lowbush blueberry planting at a home. Other fields previously identified with the disease were revisited, marked by GPS and found to still have the disease with some spread within the field. We were unable to find a field with a large enough area of this disease to conduct a field control trial. We have collected new isolates of the fungus and are collaborating with James Polashock on using microsatellites to study the genetic diversity of this fungus. Obj.2: Examine the effects of management techniques on fungal diseases of lowbush blueberries. Field surveys were made in July and the end of August in 2012 of blueberry cover, leaf loss, and percent cover of fungal stem (Phomopsis, red leaf) and leaf spot (leaf rust, powdery mildew, Septoria, false Valdensinia) diseases in the organic, low, medium and high input management systems. We will continue to look at specific input factors and their possible effects upon disease. Obj. 3: Study the biology and control of mummy berry disease. Lab experiments were conducted to determine the range of sensitivity of Monilinia vaccinii-corymbosi to the most commonly used fungicides to control this fungus, propiconazole and fenbuconazole. We conducted a fungicide field trial to test new fungicides for control of mummy berry disease. We have set up a field common garden experiment with pseudosclerotia from 4 different locations to determine if there are inherent differences in when the apothecia develop and the weather factors that affect apothecia development and longevity. We also set up a lab experiment to look at the effects of chill hours and growing degree days on the development of pseudosclerotia from different locations. We have set up plots in growers' fields to monitor development of apothecia for a mummy berry forecast system. In 2012, we provided reports on mummy berry infection as blog posts, answering machine messages and email alerts from April 3 to May 18, and then subsequent posts on other diseases. Obj. 4: Studies on emerging diseases in lowbush blueberry. We have identified 4 new fields with an early dieback of prune plants. Multiple fungi were isolated from symptomatic roots and rhizomes and fungal inoculations are being performed on potted plants to determine the causal agent. One graduate student working on fungicide sensitivity of M. vaccinii-corymbosi graduated in August, 2012. Four undergraduate students have been trained in various lab and field techniques. Presentations were made on disease problems in lowbush blueberries at Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April, May, and June and at an organic grower meeting in June. Presentations about blueberry disease research were made at the WildBrew meeting in Fredericton, NB in Oct. 2012. PARTICIPANTS: Ashley Thompson was a Masters student working on fungicide sensitivity of M. vaccinii-corymbosi and graduated in August, 2012. Four undergraduate students, Lauren McPherson, Rafael Garcia, Courtney Horton and Gregory Melcher have been trained in various lab and field techniques and worked in these areas on this project. Caleb Slemmons is a research associate who has been trained in blueberry disease work and is involved in all aspects of the research. Tamara Levitsky is a part-time research associate who has worked on maintaining Valdensinia isolates and other lab and field research. Numerous blueberry growers allowed us to set up trials or sample their fields. TARGET AUDIENCES: The target audience for information produced by this project is the commercial lowbush blueberry growers and field managers of Maine, NH and Mass., the general public living near blueberry fields, growing patches of blueberries, or interested in blueberries, and fellow researchers of blueberries. Information on using the Mummy berry forcasting method and results from field experiments was also presented to growers at the Wild Blueberry field day, mid July each year and provided on the www.wildblueberries.maine.edu website and on the blog associated with this website.In 2012, we provided reports on mummy berry infection as blog posts, answering machine messages and email alerts from April 3 to May 18, and then subsequent posts on other diseases. Presentations were made on disease problems in lowbush blueberries at Wild Blueberry Grower Extension meetings at Waldoboro, Ellsworth, and Machias in March, at blueberry growers' twilight meetings in Warren, Jonesboro, and Orland in the months of April, May, and June and at an organic grower meeting in June. Presentations about blueberry disease research were made at the WildBrew meeting in Fredericton, NB in Oct. 2012. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Obj. 1) Growers have been encouraged to eradicate any patches of Valdensinia leaf spot in their fields by a hard burn of the plant material, and this has been successful in many fields. During grower meetings in March 2012, 72% of growers answered correctly that typical prune burning does not eliminate the fungus, so our education program is working. We again confirmed that burn pruning does not eradicate this disease when we found in 2012 that disease had spread in fields which were identified with the disease in 2009. Analysis is being conducted to look for landscape features that may be associated with this disease from past fields identified as having the disease. Obj. 2) In the systems study, we found significantly more Phomopsis stem disease in medium and high input prune fields than the other input fields, as we also found in 2010. We also found significantly more leaf loss in low and organic input fields than the higher input fields. The level of Septoria leaf spot and leaf rust was significantly correlated to leaf loss. We are further examining the effects of specific inputs on these diseases. Obj.3. Isolates of M. vaccinii-corymbosi collected from three fields with multiple, bi-yearly applications of propiconazole were significantly less sensitive to propiconazole than isolates collected from a wild stand of lowbush blueberries never treated with fungicides. Isolates from three organic fields were not significantly different from isolates in the other two management types. No differences in sensitivity were found with fenbuconazole. These experiments suggest that there is the possibility of resistance to propiconazole developing in M. vaccinii-corymbosi. In fungicide trials in two fields, we found fungicides with different chemistries, different azole ingredients, and mixtures of fungicides were significantly effective at controlling mummy berry disease compared to an untreated control. One field had significantly more yield in some of the fungicide treatments than the untreated control. These data have provided new materials to use for control of this disease. Growers at field meetings answered questions about mummy berry disease correctly over 75% of the time, suggesting that education program about this disease is working. Obj.4. We have not yet identified the causal agent for the new prune stem dieback disease, but are continuing fungal inoculation studies on potted plants.
Publications
- Smith MK, Annis SL, Kaplan JJ, Drummond F. 2012. Using peer discussion facilitated by clicker questions in an informal education setting: enhancing farmer learning of science. PLoS-ONE. 2102, 7(10): e47564. doi:10.1371/journal.pone.0047564
- McGovern, K., S. Annis and D. Yarborough, 2012. Efficacy of organically acceptable materials for control of mummy berry disease on wild blueberries in Maine. International Journal of Fruit Science. 12:188-204.
- Thompson, A.A and S.L. Annis. 2012. Reduced sensitivity to propiconazole found in Monilinia vaccinii-corymbosi from lowbush blueberry fields in Maine. Abstract. Phytopathology. Accepted.
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