Source: MICHIGAN STATE UNIV submitted to NRP
PHYTOPHTHORA RESEARCH, MI
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
SPECIAL GRANT
Reporting Frequency
Annual
Accession No.
0221970
Grant No.
2010-34572-21038
Cumulative Award Amt.
(N/A)
Proposal No.
2010-01642
Multistate No.
(N/A)
Project Start Date
Jul 1, 2010
Project End Date
Jun 30, 2012
Grant Year
2010
Program Code
[YG]- Phytophthora Research, MI
Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
Plant, Soil and Microbial Science
Non Technical Summary
Phytophthora capsici is a soil mold that causes crown, fruit, and root rot. It can infect cucumber, melon, squash, pumpkin, tomato, pepper, eggplant, lima, snap and wax bean crops, and has recently been found to infect Fraser fir, a Christmas tree crop. Michigan is the number 1 producer of pickling cucumber and squash and ranks among the top 10 in the USA for the production of fresh market cucumber, snap bean, bell pepper, pumpkin and fresh market and processing tomato. Michigan cultivates 79,210 acres of Phytophthora-susceptible vegetables worth $163 million and 7,600 acres of Fraser fir worth $10.6 million. Phytophthora can be easily spread across and within agricultural regions via water. Phytophthora management is complicated by its large host range and lack of known disease resistance in vegetables. Phytophthora can last for 10 or more years in soil and it is common for growers to experience complete crop loss in some fields. Some strains of Phytophthora have mutated to become resistant to key fungicides and have colonized an estimated 25% of the acreage in the Michigan growing region. Disease outbreaks occur yearly and recent losses have become so large (up to $32.5 million) that the economic viability of these Michigan industries is at risk. This project seeks to reduce losses suffered by Michigan growers and stakeholders by developing integrated management strategies that emphasize cultural methods and environmentally friendly practices. Research will include investigating ways to limit the spread of Phytophthora; identifying and developing cultivars that are resistant to Phytophthora disease; investigating soil amendments, mulches, crop rotation and water management as new techniques for managing Phytophthora; and testing fungicides, biological control agents and new chemistries for disease control. Phytophthora management recommendations for growers will be developed from research results and demonstrated in on-farm trials and presented at extension meetings.
Animal Health Component
90%
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2161411116014%
2161420116014%
2161421116016%
2161429116014%
2161460116014%
2161461116014%
2161462116014%
Knowledge Area
216 - Integrated Pest Management Systems;

Subject Of Investigation
1460 - Tomato; 1461 - Peppers; 1411 - Beans (fresh, fresh-processed); 1420 - Melons; 1429 - Cucurbits, other; 1421 - Cucumber; 1462 - Eggplant;

Field Of Science
1160 - Pathology;
Goals / Objectives
Phytophthora is a major disease of many vegetable crops that can cause Michigan and U.S. growers to lose 25-100% of their crops annually. Through this project, a solution to this disease problem will be developed and implemented. Graduate and undergraduate students will be trained in science and sustainable, environmentally friendly agriculture. Many high school students employed as labor go on to college in related science areas. Jobs are created indirectly in rural Michigan communities by keeping family farms profitable and retaining industry jobs in agricultural vegetable production, processing and direct market sales. OBJECTIVE 1. Limit the spread of Phytophthora. 1a) Assist growers in the diagnosis and management of Phytophthora. 1b) Examine the effects of temperature and relative humidity (RH) on disease and sporulation of P. capsici. 1c) Study the diversity and population structure of P. capsici isolates collected from different hosts worldwide and Michigan surface water irrigation sources. 1d) Compare virulence and phenotypic characteristics of P. capsici isolates collected from different hosts worldwide and Michigan surface water irrigation sources on pepper and cucumber. 1e) Map the loci that confer mefenoxam resistance to P. capsici. 1f) Map the resistance found in the tomato accession LA407 to P. capsici root and fruit rot. 1g) Assess the threat of P. capsici in floriculture crops. 1h) Evaluate the effects of temperature, RH, and leaf age on infection and sporulation of P. capsici on the foliage of cucumber, watermelon, cantaloupe and pepper. OBJECTIVE 2. Identify and develop Phytophthora-resistant varieties. 2a) Determine virulence of isolates of P. capsici on squash seedlings and resistance/tolerance of the squash types and cultivars to the isolates. 2b) Assess tolerance/resistance of squash germplasm to P. capsici. 2c) Examine the role of cucumber fruit surface in preventing infection by P. capsici. OBJECTIVE 3. Develop new techniques for Phytophthora control including soil amendments, mulches, crop rotation, and water management. 3a) Test the Phytophthora susceptibility of cover crops commonly used to improve crop rotation to predict their impact on disease occurrence. 3b) Test the effect of ITCs (isothiocyanates) produced by hydrolysis of glucosinolates from mustard cover crops on P. capsici incidence. 3c) Investigate washing pits as potential postharvest sources of P. capsici inoculum for cucumber fruits. OBJECTIVE 4. Test currently labeled fungicides, biological control agents, and new chemistries for activity against Phytophthora. Identify active ingredients effective against P. capsici. DISSEMINATION: Research will be conducted in grower-cooperator's fields and featured in field days. Research findings will be integrated and presented in a grower-friendly fashion at field demonstrations, presentations, and via handouts and presented to growers, extension agents, local agricultural consultants, and agronomists at local extension meetings, a regional extension meeting, published in newsletters, scientific journals and at a website dedicated to this project.
Project Methods
Data will be statistically analyzed when possible. 1a) Fungicide sensitivity of P. capsici from growers' crops will be determined. 1b) Inoculated cucumbers will be incubated at 30-100% RH, 10-30C and disease evaluated at 48-120 hr. 1c) Allele subtraction/data analysis in a diploid organism will be tested with 7 nuclear, 3 mitochondrial genes from 300 isolates. Bioinformatic analysis will determine if some populations occur frequently in certain hosts or regions. 1d) The P. capsici collection will be characterized by mefenoxam resistance, mating type, sporangial size, pedicel length, growth at optimum temperature, presence of papillate sporangia and/or chlamydospores, virulence on inoculated fruits. 1e) Single nucleotide polymorphisms (~386 SNP, identified by the Solexa Platform) of the parents will be genotyped in 200 F2 progeny using BeadXpress. After confirming mendelian segregation, SNP data will determine correlation between loci and mefenoxam resistance. 1f) Root and fruit inoculation will evaluate disease of 65 tomato lines (inbred backcross population, LA407 x Hunt100). SNPs (~386) from the parents' genome will correlate loci resistance to root and/or fruit rot as in 1e. 1g) Calibrachoa, ornamental and vegetable hosts will be inoculated with P. capsici and Phytophthora spp. and rated for wilting, lesion, girdling severity, death. 1h) Effects of varying temperatures, relative humidities and leaf ages will be tested on P. capsici-inoculated foliage of cucumber Vlaspik, watermelon Sugar Baby, cantaloupe Athena, pepper Red Knight for disease severity. 2a) Tolerant/susceptible zucchini, yellow squash, and butternut squash will be inoculated with 5 P. capsici isolates and rated for wilting, lesion, girdling severity, plant death. 2b) Inoculated plants and fruit of cultivars and breeding lines of a squash type will be rated for wilting, lesion, girdling severity, death in the greenhouse and field. 2c) Greenhouse cucumber Vlaspik fruits of known ages will be inoculated and rated for disease. Fruit samples of different susceptibilities will be selected for RNA extraction, cDNA library preparation, 454 sequence analysis. 3a) Cover crops (Brassicaceae, Poaceae, Fabaceae, Polygonaceae) will be rated for disease after inoculating leaves (agar plugs) and roots (infested millet seed) in the greenhouse/lab. Roots will be evaluated and biomass measured. 3b) Brassica-produced isothiocyanates (ITCs) will be tested for biofumigation effects. Summer squash planted in soil inoculated with infested millet seed and treated with 0-10000 ppm ITCs will be rated for disease. 3c) Cucumber washing pit water will be monitored at farms by removing hourly samples, soaking fruit overnight and comparing with unwashed fruit collected at the farm. Data will relate the number of cucumbers loads washed, water temperature, and disease level of unwashed fruit. 4) Doses, application frequencies and efficacy of registered and experimental materials will be tested in field plots. Above-ground sprays applied with CO2 backpack sprayers will assess foliar and fruit infection, below ground applications via drip irrigation will assess root infection.

Progress 07/01/10 to 06/30/12

Outputs
OUTPUTS: Project knowledge was advanced by 51 local, regional and national presentations. Two MS students, Tiffany B. Enzenbacher and M. Catalina Cespedes-Sanchez, and one PhD student, Michael D. Meyer, graduated. Population structure of 255 P. capsici world-wide isolates was analyzed by 4 mitochondrial and 6 nuclear loci. Population structure of 106 P. capsici isolates from a water source and nearby field was analyzed by 6 nuclear loci; virulence of P. capsici from worldwide hosts was evaluated on cucuubit and solanaceous fruits by lesion/pathogen growth size and sporulation density. Phenotypic variation of 124 P. capsici world-wide isolates was determined by dimensions of sporangia, pedicles and oospores, and growth at 32, 35 and 38C. Pepper fruits of 108 recombinant inbred population lines (susceptible Early Jalapeno x partially resistant Criollo de Morelos) were evaluated for P. capsici disease resistance. An F2 fungicide resistance-mapping population of 200 P. capsici isolates (progeny of intermediately mefenoxam sensitive isolates #2 [A1 mating type (MT)] x #6 [A2]) were characterized by MT and mefenoxam resistance and genetically analyzed. A tomato inbred backcross population (62 lines, resistant LA407 x Hunt 100) was analyzed by quantitative trait loci (QTL) and introgression using 152 markers, and plants root-inoculated with P. capsici isolates. Two trials tested 9 ornamental crops (2 Fabaceae [Lathyrus, Lupinus], 5 Solanaceae [Browallia, Calibrachoa, Nicotiana, Nierembergia, Petunia], 2 Asteraceae [Osteospermum, Chrysanthemum]) for P. capsici disease. Cucumber cotyledon susceptibility was evaluated by inoculation with encysted or motile zoospores at varied concentrations and incubation times, and leaf position (cotyledon, first and second true leaves) of cucumber, yellow squash and zucchini were evaluated for P. capsici isolates susceptibility. Fruits of 8 cucurbit crops (pickling/slicing cucumber; butternut, acorn, spaghetti and straightneck squashes; zucchini; pumpkin) were evaluated for P. capsici isolates disease. Seedlings of 5 summer and 4 winter squash cultivars were evaluated for susceptibility. Susceptibility of cucumber and yellow squash fruits and cotyledons to P. capsici isolates was evaluated. Eight bean and one soybean cultivars were tested for P. capsici susceptibility. Varied-aged processing pumpkin and winter squash fruits were evaluated for age-related resistance (ARR) to P. capsici disease. ARR of cucumber fruits was evaluated by analyzing a cDNA library from exocarps and whole fruits of known ages, and testing exocarp extracts in P. capsici growth assays. Susceptibility of 12 cover crops was evaluated and five isthiocyanates (ITCs, produced by mustard on P. capsici incidence) were evaluated. Cultural effects of bed height (raised, flat), mulches (bare, straw, plastic), compost amendments (0, 2 ton/A poultry litter), zucchini cultivars (Cougar, Payroll) on disease was evaluated. Two yellow squash trials tested 11 registered fungicides and 2 application methods (foliar spray, soil-applied drench) for Phytophthora control. PARTICIPANTS: Dr. Mary Hausbeck, Michigan State University, was the Principal Investigator/Project Director and oversaw the entire Phytophthora project objectives, activities, and reporting to USDA. Dr. Mathieu Ngouajio, Michigan State University, was responsible for the biofumigant research component, and was assisted by Aristarque Djoko, technician, Drey Clark, technician, and Alexandra Prediger, labor employee. Dr. Rebecca Grumet conducted the age-related cucumber exocarp susceptibility research at Michigan State University, and was assisted by Dr. Kaori Ando, post-doctoral researcher, Sue Hammar, technician, and Marivi Colle, graduate student, and undergraduate students Alan Dosenberry, Daniel Kirchoff, Daniel Raba, Elizabeth Straley and Ciana Hodges-King. Research assistants Brian Cortright and Sheila Linderman were responsible for trial design, establishment of plots, oversight and maintenance of plots, harvest/data collection, statistical analyses, and aided in reporting and presentations. Post-doctoral researcher, Dr. Leah Granke, and graduate students Catalina Cespedes, Tiffany Enzenbacher, Mike Meyer, Rachel Naegele, Lina Quesada and Lina Rodriguez and visiting scholars Johanna Del Castillo-Munera and Angela Vargas-Berdugo were trained in conducting laboratory, greenhouse, and field experiments on various crops and provided assistance with laboratory P. capsici research. Undergraduate students and labor employees were trained as field, greenhouse and laboratory support crews to assist with graduate research projects and also provide direct support for the research assistants over the course of this project. These included undergraduate students (Halli Gutting, Jennifer Harig, Lisa Henderson, Ronnie Heslip, Jayme Olsen, Scott Mauch, Jenna Milstead, Alexandra Rodebach, Justin Schmitt, Heather Sweet) and labor employees (Jon Bloemers, Alex Cook, Adam Cortright, Tina Guo, Jarrod Morrice, James Romel, Ben Zietlow). Several commercial seed and chemical companies have provided financial or product support of chemical and variety screens. Partner organizations/collaborators for this project included Kevin Carr of the MSU Research Technology Support Facility, the Pickle and Pepper Research Committee of MSU, Pickle Packers International Inc., and the DuPont, UPI and Valent chemical companies. TARGET AUDIENCES: Many of the field research studies were conducted with the help of grower cooperators to aid in quicker adaptation of new products and control measures. Over the life of this project, research results were presented in 51 talks and posters at local, regional, national and international meetings, industry meetings and national scientific meetings attended by growers, packers, processors, industry stakeholders, extension personnel, and other researchers. Local and regional extension meetings included the Great Lakes Fruit, Vegetable and Farm Market Expo, Grand Rapids, MI, Dec 2010-11; Pickle and Pepper Research Committee Meeting, East Lansing, MI, Jan 2011 and Grand Rapids, Jan 2012; Midwest Cover Crop Council Annual Meeting, West Lafayette, IN, Feb 2012; Phytophthora and Downy Mildew Workshop, Benton Harbor, MI, Feb 2012; Fruit and Vegetable Growers Association of Delaware, Delaware Ag Week, Harrington, DE, Jan 2011-12; Empire State Fruit and Vegetable Expo, Syracuse, NY, Jan 2012; Conservation Tillage and Technology Conference, Ohio Northern University, Ada, OH, 24-25 Feb 2011; Spring Horticulture Meeting, Hart, MI, 15 Mar 2011; Integrated Pest Management Phytophthora, Decision Makers EPA Tour, Hart, Pentwater and Grant, MI, 17-18 Jul 2012; Summer Research Tour, Oceana County, MI, 6 Sep 2011. National scientific meetings included the 26th Annual Tomato Disease Workshop, Ithaca, NY, Oct 2011; 3rd International Phytophthora capsici Meeting, Hawks Cay, Duck Key, FL, 30 Nov-1 Dec 2011; Plant and Animal Genome Conference XIX, San Diego, CA, 15-19 Jan 2011; Department of Botany and Plant Pathology Seminar, Purdue University, West Lafayette, IN, Feb 2011; Annual Meeting of the American Phytopathological Society, Honolulu, HI, Aug 2011 and Providence, RI, Aug 2012; Cucurbitaceae 2010, Charleston, SC, Nov 2010. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Bayesian clustering of worldwide P. capsici isolates showed structure by host, geography and mefenoxam sensitivity. Bayesian clustering of P. capsici isolates from water detected 4 clusters by phenotype, MT and mefenoxam sensitivity; host family affected sporulation on pepper fruits. Phenotype analysis found sporangia size varied by cluster and continent of origin; length:breadth ratio and pedicle length differed by continent and host family. Most isolates grew at 35C. Pepper population lines differed for phenotype and disease characteristics; CM334, Early Jalapeno and line 4 were less susceptible than others. Fungicide resistance was mapped to 8 linkage groups; 1 quantitative trait loci (QTL) in group 5 explained 8% of MT variation and 2 QTLs in group 4 explained 6-7% of mefenoxam resistance variation. Mapping found 12 linkage groups corresponding to the 12 tomato chromosomes; 4 QTLs were found in chromosomes 1, 2 and 3. Diseased plants in P. capsici-inoculated ornamental trial 1 were: 23% Nicotiana, 65% Lupinus, 15% Calibrachoa, 7% Lathyrus; Browallia, Nierembergia and Petunia were healthy. Lathyrus and Lupinus were most diseased in trial 2; Chrysanthemum, Osteospermum, Calibrachoa were similar to the uninoculated controls. Cucumber cotyledons were infected by encysted and motile zoospores; higher concentrations and longer incubation increased disease. Foliar susceptibility of cucumber, yellow squash and zucchini decreased from cotyledon to first to second true leaves. All P. capsici isolates caused cucurbit fruit rot but virulence differed. Straightneck summer squash had larger lesions and pathogen growth than zucchini; butternut had larger lesions than pumpkin and spaghetti squash. All P. capsici isolates infected cucumber and yellow squash fruits and cotyledons; larger lesions with more sporangia occurred on squash. Snap beans were more susceptible than dry beans and soybean; stem, petiole/leaf and pod tissues were susceptible to disease but roots and soybean pods were resistant. Less than 15% of Dickenson Field processing pumpkin fruits 21 days post pollination (dpp) or older became diseased; 80% of Golden Delicious winter squash fruits became diseased; soluble solids content and exocarp firmness increased with age. Changes in the cucumber exocarp genetics from 8 to 16 dpp reflect changes from photosynthesis to cuticle production. Exocarp extracts from 12 and 16 dpp fruits inihibited P. capsici growth and sporulation compared with 4 or 8 dpp fruits. Biomass accumulation was not affected for any cover crop and only yellow mustard Tilney showed some disease symptoms. None of the 5 ITCs reduced P. capsici disease, possibly due to low concentrations and late application timing. Cultural trials found Cougar more susceptible than Payroll; raised beds decreased Payroll death. Plant death 42 days postinoculation was 41% for soil fungicide drenches and 92% for foliar sprays. Fluopicolide, mandipropamid or dimethomorph drenches limited death to <10% and prevented yield loss. Foliar sprays could not prevent yield loss in field trials. Some treatments were more effective on Leopard.

Publications

  • Ackroyd J.V., and M. Ngouajio. 2011. Brassicaceae cover crops affect seed germination and seedling establishment in cucurbit crops. HortTechnology 21:525-532.
  • Bi, Y., Jiang, H.H., Hausbeck, M.K., and Hao, J.J. 2012. Inhibitory effects of essential oils for controlling Phytophthora capsici. Plant Disease 96:797-803.
  • Cespedes-Sanchez, M.C. 2012. Host susceptibility to two Peronosporales among cucurbits and beans. M.S. Thesis, Michigan State University.
  • Enzenbacher, T.B., and Hausbeck, M.K. 2011. Evaluation of fungicides for control of Phytophthora pod rot of lima bean, 2010. Plant Disease Management Report 5:V121.
  • Enzenbacher, T.B., and Hausbeck, M.K. 2012. An evaluation of cucurbits for susceptibility to cucurbitaceous and solanaceous Phytophthora capsici isolates. Plant Disease 96 (online: First Look).
  • Foster, J.M., Naegele, R.P., and Hausbeck, M.K. 2012. Evaluation of potential eggplant rootstocks and pepper varieties for resistance to Michigan and New York isolates of Phytophthora capsici. Plant Disease (accepted with revision).
  • Granke, L., Quesada-Ocampo, L., Lamour, K., and Hausbeck, M. 2012. Advances in research on Phytophthora capsici on vegetable crops. Plant Disease 96 (online:First Look).
  • Granke, L., Quesada-Ocampo, L.M., Lebeis, A., Henderson, L., VanOverbeke, M., and Hausbeck, M. 2012. Morphological and physiological variation within Phytophthora capsici isolates from a worldwide collection. Abstr. Phytopathology 102:S4.47.
  • Granke, L.L., and Hausbeck, M.K. 2011. Dynamics of Pseudoperonospora cubensis sporangia in commercial cucurbit fields in Michigan. Plant Disease 95:1392-1400.
  • Granke, L.L., Quesada-Ocampo, L.M., and Hausbeck, M.K. 2011. Differences in virulence of Phytophthora capsici isolates from a worldwide collection on tomato fruits. Abstr. Page 35 in Proceedings of the 26th Annual Tomato Disease Workshop, Cornell University, Ithaca, NY, Oct 11-13.
  • Granke, L.L., Quesada-Ocampo, L.M., and Hausbeck, M.K. 2012. Differences in virulence of Phytophthora capsici isolates from a worldwide collection on host fruits. European Journal of Plant Pathology 132:281-296.
  • Hausbeck, M. 2011. Look for Phytophthora disease on summer squash and zucchini now. MSU Extension News for Agriculture - Vegetables: Jun 22. Online.
  • Hausbeck, M. 2011. Look for Phytophthora disease on winter squash and pumpkin now. MSU Extension News for Agriculture - Vegetables: Jun 22. Online.
  • Hausbeck, M.K. 2011. Use integrated management strategies with Phytophthora on peppers. MSU Extension News for Agriculture - Vegetables: Jul 29. Online.
  • Hausbeck, M.K., and Cortright, B.D. 2012. Evaluation of fungicides for control of Phytophthora and Pythium fruit rots of pickling cucumber, 2011. Plant Disease Management Report 5:V135. Online.
  • Lu, X., Hausbeck, M., Liu, X., and Hao, J.J. 2011. Risk assessment of Phytophthora capsici resistant to fluopicolide. Abstr. Phytopathology 101:S110.
  • Lu, X.H., Hausbeck, M.K., and Hao, J.J. 2011. Wild type sensitivity and mutation analysis for resistance risk to fluopicolide in Phytophthora capsici. Plant Disease 95:1535-1541.
  • Meyer, M.D. 2012. Management of Phytophthora capsici on summer squash and age-related resistance on processing pumpkin and winter squash fruits. Ph.D. Dissertation, Michigan State University.
  • Meyer, M.D., and Hausbeck, M.K. 2012. Using cultural practices and cultivar resistance to manage Phytophthora crown rot on summer squash. HortScience 47(8):1080-1084.
  • Meyer, M.D., and Hausbeck, M.K. 2012. Using soil-applied fungicides to manage Phytophthora crown and root rot on summer squash. Plant Disease (online: First Look).
  • Morrice, J.J., and Hausbeck, M.K. 2011. Controlling cucumber diseases under extreme production conditions. Pages 5-9 in: Pickling Cucumber Session Summaries, Great Lakes Fruit, Vegetable and Farm Market Expo. Online.
  • Nair, A., and Ngouajio, M. 2011. Integrating Brassica cover crops into onion cropping systems: Implications for plant population, stand establishment, and yield. Abstr. HortScience 46(9):S203.
  • Ngouajio, M. 2012. Stress defenders: Acting as biofumigants, Brassica cover crops help reduce insects, weeds, and disease. American Vegetable Grower Magazine May issue, p. 16.


Progress 07/01/10 to 06/30/11

Outputs
OUTPUTS: Population structure of 255 P. capsici world-wide isolates was analyzed by 4 mitochondrial and 6 nuclear loci. Population structure of 106 P. capsici isolates from a water source and nearby field was analyzed by 6 nuclear loci. Virulence of P. capsici from worldwide hosts was evaluated on cucumber, zucchini, tomato and pepper fruits by lesion/pathogen growth size and sporulation density. Phenotypic variation of 124 P. capsici world-wide isolates was determined by dimensions of sporangia, pedicles and oospores; production of sporangia and chlamydospores; and growth at 32, 35 and 38C. Pepper fruits of 108 recombinant inbred population lines (susceptible 'Early Jalapeno' x partially resistant 'Criollo de Morelos') were evaluated for P. capsici and P. nicotianae disease. An F2 fungicide resistance-mapping population of 200 P. capsici isolates (progeny of intermediately mefenoxam sensitive isolates #2 [A1 mating type (MT)] x #6 [A2]) were characterized by MT and mefenoxam resistance and genetically analyzed. A tomato inbred backcross population (62 lines, resistant LA407 x Hunt 100) was analyzed by QTL (quantitative trait loci) and introgression using 152 markers, and plants root-inoculated with P. capsici OP97 and 12889. Seven ornamental crops (2 Fabaceae [Lathyrus, Lupinus], 5 Solanaceae [Browallia, Calibrachoa, Nicotiana, Nierembergia, Petunia]) were evaluated for P. capsici OP97, SP98, 12889 and 13351 disease. Six ornamental Calibrachoa cultivars were evaluated for disease susceptibility. Cucumber cotyledon susceptibility was evaluated by inoculation with encysted or motile zoospores at varied concentrations and incubation times. Leaf position (cotyledon, first and second true leaves) of cucumber, yellow squash and zucchini were evaluated for P. capsici OP97, SF3, SP98 and 12889 susceptibility. Fruits of 8 cucurbit crops (pickling and slicing cucumber; butternut, acorn, spaghetti and straightneck squashes; zucchini; pumpkin) were evaluated for P. capsici SF3, OP97, SP98 and 12889 disease. Seedlings of 5 summer and 4 winter squash cultivars were evaluated for susceptibility. Susceptibility of cucumber and yellow squash fruits and cotyledons to P. capsici 12889, 13351, OP97, SF3 and SP98 was evaluated. Varied-aged processing pumpkin and winter squash fruits were evaluated for P. capsici 12889 disease. Age-related decrease in disease susceptibility of cucumber fruits was evaluated by preparing a cDNA library from exocarps of fruits of known ages and whole fruit samples, performing a 454 analysis and aligning with the cucumber genome; BLAST analysis searched for homologs and assigned putative gene functions. Susceptibility of 12 cover crops was evaluated. Cultural effects of bed height (raised, flat), mulches (bare, straw, plastic), compost amendments (0, 2 ton/A poultry litter), zucchini cultivars (Cougar, Leopard) on disease was evaluated. Two yellow squash trials tested 11 registered fungicides and 2 application methods (foliar spray, soil-applied drench) for Phytophthora control. Go to http://veggies.msu.edu/Phytophthora/Phytophthorahome.htm for this project's website. Tiffany Enzenbacher received her M.S. in 2011. PARTICIPANTS: Dr. Mary Hausbeck, Michigan State University, was the Principal Investigator/Project Director and oversaw the entire Phytophthora project objectives, activities, and reporting to USDA. Dr. Mathieu Ngouajio, Michigan State University, was responsible for the biofumigant research component, and was assisted by Aristarque Djoko, undergraduate student. Dr. Rebecca Grumet conducted the age-related cucumber exocarp susceptibility research at Michigan State University, and was assisted by Dr. Kaori Ando, post-doctoral researcher and Marivi Colle, graduate student. Research assistants Brian Cortright and Sheila Linderman were responsible for trial design, establishment of plots, oversight and maintenance of plots, harvest/data collection, statistical analyses, and aided in reporting and presentations. Post-doctoral researcher, Dr. Leah Granke, and graduate students Catalina Cespedes, Tiffany Enzenbacher, Mike Meyer, Rachel Naegele, Lina Quesada and Lina Rodriguez and visiting scholars Johanna Del Castillo-Munera and Angela Vargas-Berdugo were trained in conducting laboratory, greenhouse, and field experiments on various crops and provided assistance with laboratory P. capsici research. Undergraduate students and labor employees were trained as field, greenhouse and laboratory support crews to assist with graduate research projects and also provide direct support for the research assistants over the course of this project. These included undergraduate students (Halli Gutting, Jennifer Harig, Lisa Henderson, Ronnie Heslip, Jayme Olsen, Scott Mauch, Jenna Milstead, Alexandra Rodebach, Justin Schmitt, Heather Sweet) and labor employees (Jon Bloemers, Alex Cook, Adam Cortright, Tina Guo, Jarrod Morrice, James Romel, Ben Zietlow). Several commercial seed and chemical companies have provided financial or product support of chemical and variety screens. Partner organizations for this project included the Pickle and Pepper Research Committee of MSU, Pickle Packers International Inc., and the DuPont, UPI and Valent chemical companies. TARGET AUDIENCES: Many of the field research studies were conducted with the help of grower cooperators to aid in quicker adaptation of new products and control measures. Information about this project can be found online at http://veggies.msu.edu/Phytophthora/Phytophthorahome.htm. Research results were presented in 22 talks at local, regional, national and international meetings, industry meetings and national scientific meetings attended by growers, packers, processors, industry stakeholders, extension personnel, and other researchers. Local and regional extension meetings included the Great Lakes Fruit, Vegetable and Farm Market Expo, Grand Rapids, MI, 7-9 Dec 2010; Pickle and Pepper Research Committee Meeting, East Lansing, MI, 14 Jan 2011; Delaware Ag Week, Harrington, DE, 18-20 Jan 2011; Conservation Tillage and Technology Conference, Ohio Northern University, Ada, OH, 24-25 Feb 2011; Spring Horticulture Meeting, Hart, MI, 15 Mar 2011; Summer Research Tour, Oceana County, MI, 6 Sep 2011. National scientific meetings included the Plant and Animal Genome Conference XIX, San Diego, CA, 15-19 Jan 2011; Department of Botany and Plant Pathology Seminar, Purdue University, West Lafayette, IN, Feb 2011; Annual Meeting of the American Phytopathological Society, Honolulu, HI, 6-10 Aug 2011. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Knowledge of this project was advanced by 22 local, regional and national presentations. Bayesian clustering of worldwide P. capsici isolates revealed some population structure by host, geography and mefenoxam sensitivity. Bayesian clustering of P. capsici isolates from water detected 4 clusters by phenotype, MT and mefenoxam sensitivity; host family affected sporulation on pepper. Phenotype analysis showed sporangia (23-35 um wide x 28-60 um long) varied by cluster and continent of origin. Length:breadth ratio (1.34-2.07) and pedicle length (20-260 um) differed by continent and host family. Oospore diameters (22-37 um) did not genetically differ. Sporangia production differed by continent and host. Chlamydospores were produced by 35 isolates. Most isolates grew at 35C but all grew poorly at 38C. Pepper population lines had significant differences in fruit rot resistance. Isolates of a fungicide-resistance mapping population showed a pattern segregation distortion ratio of 1:2:1. Ten tomato population lines were resistant to P. capsici OP97 and 12889; 20 were resistant to OP97. Mapping found 12 linkage groups corresponding to the 12 tomato chromosomes; 4 QTLs were identified in chromosomes 1, 2 and 3. Integration found 1.4-32.3% of the LA407 genome present in lines. Diseased plants in ornamental crops were: 23% Nicotiana, 65% Lupinus, 15% Calibrachoa, 7% Lathyrus. Calibrachoa cultivar disease ranged from 92% (Can-Can Apricot) to 75% (Cabaret Yellow, Callie Gold with Red Eye). Cucumber cotyledons were infected by encysted and motile zoospores; higher concentrations and longer incubation increased disease. Foliar susceptibility of cucumber, yellow squash and zucchini decreased from cotyledon to first to second true leaves. All P. capsici isolates caused cucurbit fruit rot but virulence differed. SF3 caused smaller lesions with reduced pathogen growth. Summer squash: straightneck had larger lesions and pathogen growth than zucchini. Winter squash: butternut had larger lesions than pumpkin and spaghetti squash. Symptom appearance and disease progress were significant for inoculated seedlings of summer and winter squash cultivars, and differences between two butternut and two zucchini cultivars were found. All P. capsici isolates infected cucumber and yellow squash fruits and cotyledons; significantly larger lesions with more sporangia occurred on squash. Fruit disease varied with P. capsici isolate and more sporangia were produced on cucumber than squash. Preliminary data indicates that younger pumpkin and winter squash fruits are more susceptible than older. Genetic analysis of exocarp-associated age-related decrease in cucumber fruit susceptibility is ongoing. Only yellow mustard 'Tilney' showed some disease symptoms; biomass accumulation was not affected for any cover crop. Regardless of cultural effects, plant death occurred in all plots and analysis is ongoing. Drench applications of registered fungicides reduced plant death (35 and 52% for trials 1 and 2, respectively) compared to foliar applications (85 and 87%). The most effective treatments in both trials were drenches of Presidio 4SC, Revus 2.08SC and Forum 4.17SC.

Publications

  • Enzenbacher, T.B. 2011. M.S. An evaluation of cucurbits and ornamentals to Phytophthora spp. M.S. Thesis, Michigan State University, East Lansing.
  • Granke, L.L., Quesada-Ocampo, L.M., and Hausbeck, M.K. 2011. Variation in phenotypic characteristics of Phytophthora capsici isolates from a worldwide collection. Plant Disease 95:1080-1088.
  • Granke, L., Quesada-Ocampo, L.M., Lebeis, A., Henderson, L., VanOverbeke, M. and Hausbeck, M. 2011. Global phenotypic variation in Phytophthora capsici. Abstr. Phytopathology 101:S63.
  • Granke, L., Quesada-Ocampo, L.M., Wood, M., Olsen, J., Mercier, M. and Hausbeck, M. 2011. Differences in virulence of Phytophthora capsici isolates from a global collection. Abstr. Phytopathology 101:S63.
  • Grumet, R., and Ando, K. 2011. Rapidly expanding cucumber (Cucumis sativus) fruit show enriched expression of novel transcripts. Abstr. Plant and Animal Genome Conference XIX, San Diego CA, Jan 15-19. http://www.intl-pag.org/19/abstracts/P01_PAGXIX_048.html.
  • Quesada-Ocampo, L.M., Granke, L.L., Mercier, M.R., Olsen, J., and Hausbeck, M.K. 2011. Investigating the genetic structure of Phytophthora capsici populations. Phytopathology: 1061-1073.
  • Quesada-Ocampo, L., Granke, L., Mercier, M., Olsen, J., and Hausbeck, M. 2011. Investigating the genetic structure of Phytophthora capsici populations. Abstr. Phytopathology 101:S149.