New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Final Report for LNC03-228

Project Type: Research and Education
Funds awarded in 2003: $99,289.00
Projected End Date: 12/31/2006
Matching Federal Funds: $32,248.00
Region: North Central
State: Illinois
Project Coordinator:
Mohammad Babadoost
University of Illinois
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Project Information

Summary:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Summary

Phytophthora blight, caused by Phytophthora capsici, is the most serious threat to production of cucurbits and peppers in the North Central region in the United States. Integrated disease management practices developed in this research effectively minimize crop losses of cucurbits and peppers caused P. capsici. An integrated approach of seed-treatment, disking the localized infected areas, and fungicide applications is effective for controlling of Phytophthora blight in cucurbit fields. Phytophthora blight of pepper is effectively controlled by either planting identified resistant varieties or application of fungicides. Red-light treatment is effective for controlling Phytophthora blight in greenhouses.

Introduction:

New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Introduction

Among all states, Illinois ranks first in pumpkin production (2). Approximately 21,000 acres of farmland in Illinois are planted to pumpkins annually. More than 90% of the commercial processing pumpkins (Cucurbita moschata) in the United States (US) are produced on approximately 10,000 acres and processed in Illinois (3). Jack-o-lantern pumpkins are produced in more than 11,000 acres throughout Illinois. In addition, approximately 10,000 acres in Illinois are in production of cucumbers, gourds, melons, squashes, watermelons, eggplants, peppers, and tomatoes (1,2). Peppers are produced in about 1,000 acres. Also, considerable amounts of these vegetables are produced in home gardens throughout the state.

Phytophthora blight, caused by Phytophthora capsici, has become one of the most serious threats to production of cucurbit crops (cucumbers, gourds, melons, pumpkins, squashes, watermelons), eggplants, peppers, and tomatoes (2,3,4,13,20). This disease was almost unknown in Illinois before 1998. But, because of unknown reasons, the disease was in epidemics in Illinois during 1998-2003 causing up to 100% yield losses in the above-mentioned vegetables (2,3,4,13). Yield losses up to 100% in pepper, up to 30% in jack-o-lantern pumpkin, up to 100% in processing pumpkin, up to 50% in squash, and up to 80% in melon, tomato, and watermelon fields occurred (2,3). The estimated yield and product losses in Illinois to P. capsici, in pumpkins and peppers, exceeded $10,000,000 per year (2,3).

P. capsici was first described on peppers in New Mexico in 1922 (21). The pathogen was subsequently reported on cucurbit crops (cucumbers, gourds, melons, pumpkins, squashes, watermelons), eggplants, tomatoes, and several other crops from vegetable growing areas in the world (2,9,20,32). The pathogen produces coenocytic diploid hyphae, sporangia, zoospores, and oospores (9). Zoospores, which are produced in abundance during the growing season, cause infection in the crops (9). Oospores, commonly produced at the end of growing season, are important in the life cycle of the pathogen both as primary survival structures and as the site of genetic recombination (9,11). This pathogen can grow and infect host plant at 11 to 35C (9,32).

P. capsici is a soil-borne and airborne pathogen. It survives in the soil for many years. P. capsici can strike host plants at any time from planting through harvest (2,9,32). Symptoms produced by this pathogen include pre- and post-emergence damping-off, root rot, crown rot, stem lesions, leaf spots, foliar blight, and fruit rot (2,3,5,32). Some of the hosts (e.g., eggplants, peppers, and tomatoes) are more susceptible in early growth stages (5). Phytophthora infections develop and spread rapidly, because sporangia are produced on infected tissues and dispersed by water and air. There was no effective method available to provide adequate control of P. capsici on susceptible hosts. A recommended practice for reducing the incidence of disease in the fields was an approach of combining long-term crop rotation, sanitation, and management of field moisture (9,32). This approach did not provide adequate protection to crops against P. capsici because (i) the pathogen survives in the soil indefinitely, and (ii) in the areas with high relative humidity and/or rainfall, the management of the field moisture for control of the disease is not feasible. Other practices, including amending the soil by adding yard-waste, using cover crops, straw mulching, and soil solarization, and using antagonistic fungi for protecting crops in the fields have been investigated, but none of them have provided adequate protection against P. capsici (5,23,24,32). Fungicides might be used to protect plants against P. capsici (18,2829). However, the efficacy of fungicides in protecting the crops against P. capsici varied considerably from one area to another.

It has been reported that light of long wavelengths (red region; 600-700 nm) induces strong resistance in plants against Bipolaris oryzae, Botrytis cinerea, and Alternaria tenuissima (15,17). Red-light treatment resulted in production of anti-fungal substances in leaf tissues, suppressed the germination of fungal spores. Another report indicated that red-light treatment induced anti-fungal substances in plant tissues that suppressed the germination of spores of several plant pathogenic fungi, including soilborne pathogens (16). One other report has indicated that red-light treatment induced resistance in eggplants, peppers, and watermelons, which were suppressive against P. capsici (31).

A unique feature of Phytophthora species throughout the literature is the higher incidence of vegetable diseases in soils low in calcium (8,9). Calcium nutrition affects the incidence of diseases in several ways. First, Ca is essential for stability of biomembranes; when Ca is low, the efflux of low-molecular-weight compounds from the cytoplasm to apoplasm is increased. Second, calcium polygalacturonates are required in the middle lamella for cell wall stability. Most parasitic fungi invade the apoplasm by releasing pectolytic enzymes, which dissolve the middle lamella. The activity of these enzymes is strongly inhibited by Ca (7). The susceptibility of plants to infection with pathogens is therefore inversely related to the Ca content of the tissue (22). For example, preharvested pod rot in peanut, caused by P. myriotylum, has been closely linked to the Ca content of the pod tissue, and can be controlled by soil application of Ca sources, such as gypsum (10). The effects of calcium compounds on the incidence of seedling blight of pepper, caused by P. capsici (26,27), black shank of tobacco, caused by P. parasitica, (19), and Phytophthora diseases in plants in general (27,30), have been studied.

References:
1. Anonymous. 2004. USDA Agricultural Statistics. USDA, National Agricultural Statistical Service, Washington, DC. Http://www/usda.gov/nass/pubslhtm.

2. Babadoost, M. 2000. Incidence and Impact of Phytophthora diseases on Illinois vegetables – SIU Horticulture Day 2000:22-25.

3. Babadoost, M. 2000. Outbreak of Phytophthora foliar blight and fruit rot in processing pumpkin fields in Illinois – Plant Diseases – 84:1345.

4. Babadoost, M. and Islam, S.Z. 2001. Seed-treatment for control of seedling death of pumpkin caused by Phytophthora capsici. 2001 annual meeting of the American Phytopathological Society (Abstract).

5. Baucher, T.J., and Ashley, R.A. 2000. Northeast Pepper Integrated Pest Management (IPM) Manual. University of Connecticut Cooperative Extension System. 136 pp.

6. Barksdale, T.H., and Papavizas, G.C. 1984. Resistance to foliar blight and crown rot of pepper caused by Phytophthora capsici. Plant Disease 68:506-509.

7. Bateman, D.F., and Lumsden, R.D. 1965. Relation between calcium content and nature of the pectic substances in bean hypocotyls to susceptibility to an isolate of Rhizoctonia solani. Phytopathology 55:734-738.

8. Brady, N.C. and R.R. Weil. 1999. The nature and properties of soils. 12th ed. Prentice Hall, NY.

9. Erwin, D.C., and Ribeiro, O.K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, MN. 562 pp.

10. Hallock, D.L. and Garren, K.H. 1968. Pod breakdown, yield and yield quality of Virginia type peanuts as affected by Ca, Mg, and K sulfates. Agron. J. 60:253-257.

11. Hwang, B.K., Kim, Y.J., and Kim, C.H. 1996. Differential interactions of Phytophthora capsici isolates with pepper genotypes at various plant growth stages. Korean Journal of Plant Pathology 102:311-316.

12. Illinois Specialty Growers Association. 1993. Fruit and Vegetable Statistics. Illinois Agricultural Statistics Service, USDA/IDOA. 34 pp.

13. Islam, S.Z., Babadoost, M., and Honda, Y. 2001. Red light therapy for management of seedling death caused by Phytophthora capsici in pumpkin and tomato. 2001. Annual Meeting of the American Phytopathological Society (Abstract).

14. Islam, S.Z., and Honda, Y. 1996. Influence of phototropic response of spore germ tubes on infection process in Colletotrichum lagenarium and Bipolaris oryzae. Mycoscience 37(1):331-337.

15. Islam, S.Z., Honda, Y., and Arase, S. 1998. Light-induced resistance of broadbean against Botrytis cinerea. J. Phytopathology 146(10):479-485.

16. Islam, S.Z., Honda, Y., and Arase, S. 1999. Some characteristics of red light-induced substance(s) against Botrytis cinerea produced in broadbean leaflets. J. Phytopathology 147:65-70.

17. Islam, S.Z., Honda, Y., and Sonhaji, M. 1998. Phototropism of conidial germ tubes of Botrytis cinerea and its implication in plant infection processes. Plant Disease 82:850-856.

18. Johnston, S.A. 1989. Evaluation of fungicides for the control of the foliar phase of Phytophthora blight, 1988. Fungicide and Nematicide Tests 44:117, p. 115.

19. Kincaid, R.R., Martin, F.G., Gammon, N., Breland, H.L., and Pritchett, W.L. 1970. Multiple regression of tobacco black shank, root knot, and coarse root indexes in soil pH, potassium, calcium, and magnesium. Phytopathology 60:1513-1516.

20. Latin, T., and Rane, K. 1999. Identification and Management of Pumpkin Diseases. Purdue University, BP-17. 15 pp.

21. Leonian, L.H. 1922. Stem and fruit blight of peppers caused by Phytophthora capsici. Phytopathology 12:401-408.

22. Marschner, H. 1995. Mineral nutrition of higher plants. 2nd ed. Academic Press.

23. McGrath, M.T. 1995. Evaluation of Gliocladium virens as a biocontrol agent for managing Phytophthora in cucurbits. 1994. Biological and Cultural Tests. 10:146.

24. McGrath, M.T. 1997. Evaluation of solarization and sorghum grass for managing Phytophthora crown rot and fruit in pumpkin, 1995-1996. Biological and Cultural Tests, 12:159.

25. McGrath, M.T., Superak, T.H. 1999. Susceptibility of pumpkin varieties and experimental to Phytophthora fruit rot in pumpkin, 1998. Biological and Cultural Tests, 14:173.

26. Muchovej, J.J., Mafia, L.A., and Muchovej, R.M.C. 1980. Effect of exchangeable soil aluminum and alkaline calcium salts on the pathogenicity of Phytophthora capsici from green pepper. Phytopathology 70:1212-1214.

27. Schmitthenner, A.F. and Canaday, C.H. 1983. Role of chemical factors in development of Phytophthora diseases. P. 189-196. In: Phytophthora: Its biology ecology, taxonomy, and pathology. D.C. Erwin, S. Bartnicki-Garcia, and P.H. Tsao (eds). American Phytopathological Society, St. Paul, MN.

28. Shishkoff, N., and McGrath, M.T. 1999. Evaluation of fungicides for Phytophthora fruit rot and tip blight of summer squash, 1998. Fungicide and Nematicide Tests 54:192.

29. Stevenson, W.R., James, R.V., and Rand, R.E. 2001. Evaluation of selected fungicides to control Phytophthora blight and fruit rot of cucumber, 1200. 2001 MWFPA Processing Crops Manual and Proceedings: 145-146.

30. Swiader, J.M., Ware, G.W., and McCollum, J.P. 1992. Producing Vegetable Crops. 4th ed. Interstate Publishers, Danville, IL.

31. Umezu, H., Islam, S.Z., and Honda, Y. 1999. Red light-induced resistance in some plants. Bull. Assoc. Plant Protect. Shimane pref. 24:55-57.

32. Zitter, A.T., Hopkins, D.L., and Thomas, C.E. 1998. Compendium of Cucurbit Diseases. APS Press, St. Paul, MN. 87 pp.

Project Objectives:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Objectives/Performance Target

Objective 1: Evaluate the effectiveness of plant resistance induced by red-light treatment for control of Phytophthora blight and other diseases in pumpkin, watermelon, and pepper.

Objective 2: Determine the effects of calcium on the incidence and severity of Phytophthora blight and other diseases in pumpkin, watermelon, and pepper by soil application of CaSO4 and foliar application of CaCl2.

Objective 3: Determine the efficacy of a new copper compound (Cuprofix Disperss) on controlling Phytophthora blight and other diseases in pumpkin, watermelon, and pepper.

Objective 4: Determine the effectiveness of seed-treatment for control of seedling death caused by P. capsici in cucurbit crops.

Objective 5: Determine the effectiveness of integrated approaches of red-light treatment, calcium application, cooper spray, and seed-treatment on controlling Phytophthora blight and other diseases in vegetable farms.

Research

Materials and methods:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Materials and Methods

Characteristics of P. capsici isolates in Illinois. This study was conducted to investigate morphological, pathogenic, and genetic variations among P. capsici isolates from processing pumpkin fields in Illinois. Fifty-seven single-zoospore isolates of P. capsici, collected from 22 processing pumpkin fields at six towns in central Illinois during 2000-2001, were used in this study. All 57 isolated were used to study colony characteristics, mating types, sporangial morphology, and chlamydospore formation. Twenty-four isolates were tested for their pathogenicity on pumpkin seedlings in a greenhouse by inoculating plants with P. capsici zoospores. Random amplified polymorphic DNA (RAPD) markers were employed to assess genetic variation among twenty-four isolates of P. capsici from 10 individual fields at six locations.

Red-light treatment
Greenhouse experiments. Sporangial suspensions in sterilized-distilled water (SDW) were prepared from 5- to 6-day-old culture plates of P. capsici grown on LBA at 75 F under continuous white fluorescent light. The suspension was then incubated at 68 F for 1 h to allow the sporangia to release their zoospores. Zoospores were separated from the empty sporangia by passing the suspension through a 4-layered facial tissue (Kleenex). The concentration of zoospores was adjusted to 2×105 zoospores/ml water using a haemocytometer.

Inoculum for artificial soil infestation was prepared by growing P. capsici on oat meal-V8-juice broth (V8JB) substrate in 1-L conical flasks. The substrate, consisting of 200 g oatmeal and 120 ml V8-juice broth per liter, was autoclaved for 30 min and inoculated with mycelial plugs, 7 mm in diameter, taken from the margin of a young colony of P. capsici grown on LBA. The flasks were then incubated at 75 F in darkness. After 6 weeks, the colonized oatmeal was added to steamed soil mix (soil : sand : peat; 1:1:1) and mixed thoroughly. The inoculum potential of the soil mix was 600 colony forming units (cfu) per gram of soil, which was determined by the dilution-plate-count method.

Seeds of bell pepper (Capsicum annum; Hybrid SPP 6112, Sakata Co., Morgan Hill, CA), processing pumpkin (Cucurbita moschata; cultivar Dickinson, Libby’s Pumpkin Processing Co., Morton, IL), and tomato (Lycopersicon esculentum; Hybrid XTM 6217, Sakata Co., Morgan Hill, CA) were sown in 10-cm-diameter plastic pots (one seed per pot) containing steamed soil mix and were grown on a greenhouse bench under continuous red light irradiation (600-700 nm) from fluorescent tubes (FL20S•R-F, National Co., Japan). The fluorescent tubes provided red light with an intensity of 287 µW/cm2, which was a supplement to natural daylight. Control seedlings were kept under continuous white light (WL; FL20SS•D/18, Mitsubishi, Tokyo, Japan; 380-740 nm; 473 µW/cm2) or under natural daylight (NDL) in the same greenhouse. Three- or four-week-old seedlings were transferred from red light to NDL and inoculation was accomplished by adding the suspension of motile zoospores over the surface of the soil in each pot (5 ml/seedling/pot). Control seedlings either grown in WL or NDL were also inoculated using the same procedure. An additional set of control seedlings were inoculated with SDW only. Seedlings were watered before inoculation to keep the soil wet. After inoculation, the pots were placed in plastic trays containing water that kept the soil moist for at least 12 hours. The seedlings were then placed on a greenhouse bench, on a randomized complete design, and watered twice daily. Pumpkin and tomato seedlings were also inoculated by transplanting the seedlings into artificially infested soils in pots. Each pot contained one seedling and 14 pots were used for each treatment. Beginning the 4th day after inoculation, seedlings were evaluated for damping-off symptoms every day for 15 successive days. The seedlings were also evaluated on the 20th day after inoculation. Height, and fresh and dry weight of seedlings were also measured. Dry weight was determined after drying the seedlings at 158 degrees F (70 degrees C) for 24 hrs. Data were analyzed using analysis of variance procedures (SAS Institute, Cary, NC).

Optimizing red-light treatment. Experiments were conducted in the greenhouse to optimize the effectiveness of red-light treatment for control of Phytophthora blight of vegetables. The optimization involved determining irradiation duration (days), time of irradiation (number of hours per day and night time vs. day time irradiation), and intensity of irradiation. Pepper, pumpkin, and tomato plants were included in the experiments. Inoculation of plants and evaluation of plants for induced resistance are as described above.

Red-light trials in pepper field. During 2002-2004, field trials were conducted in a naturally infested field with P. capsici near Shawneetown, IL. Bell pepper cultivars California Wonder, King Arthur, Brigardier, Emerald Isle, and Paladin included in this study. ‘King Arthur,’ ‘California Wonder,’ and ‘Brigardier’ are susceptible cultivars and Emerald Isle and Paladin have been identified as resistant to Illinois isolates of P. capsici. Seedlings were either grown under continues red light for four weeks or under natural day light (control plants) in a greenhouse. Eight-week-old seedlings were transplanted in May into raised beds with drip irrigation and black plastic mulch. Disease incidence was determined as percent wilted or dead plants on a weekly schedule one week after transplanting until middle of August.

Red-light trials in pumpkin and watermelon fields. During 2002-2004, the trials were conducted in irrigated fields near Pekin, IL. Processing pumpkin cultivar Dickinson and watermelon cultivar Royal Sweet were included in this study. Seedlings were either grown under continues red light for four weeks or under natural day light (control plants) in a greenhouse. The seedlings were transplanted into the filed plots in June. Disease incidence and severity on leaves and vines were evaluated at three locations (11 sq. ft each) in each plot. Ten fruits were examined in each plot for Phytophthora infection. Disease incidence was determined as percent leaves, vines, or fruits affected. Disease severity was determined as percent area of leaf or vine affected. Numbers of uninfected and infected fruit with P. capsici were recorded at harvest in September. Weight of uninfected fruit was measured. The data were analyzed using GLM procedures of SAS.

Seed treatment.

Laboratory studies. Five isolates of P. capsici, collected from commercial processing pumpkin fields in Illinois, were used in this research. Fungicides mefenoxam (Apron XL LS, Syngenta Crop Protection, Inc., Greensboro, NC) and metalaxyl (Allegiance LS, Gustafson LLC, Plano, TX) were evaluated for their effectiveness in inhibiting mycelial growth, sporangium and zoospore germination. All of the laboratory experiments were repeated twice.

P. capsici was grown on LBA for 4 days at 75 degrees F in darkness. Mycelial plugs, 7 mm in diameter, were removed from actively growing margins of the culture and transferred onto the center of each LBA plate previously amended with mefenoxam or metalaxyl at 0, 1, 5, 10, 20, 50, 100, 150, and 200 μg a.i./ml. Plates were incubated in the dark at 75 degrees C for 6 days to evaluate mycelium growth. Colony diameter of P. capsici was measured in two directions for each individual plate and averaged.

To evaluate the effects of these fungicides on sporangium germination, the isolates were grown on LBA under continuous fluorescent light (F20T12/CW, Phillips Lighting Co., Somerset, NJ) at 75 degrees C for 7 days. Then, sporangial suspension was prepared in SDW. Aliquots of the sporangial suspension (400 μl) were immediately pipetted onto Petri plates containing LBA amended with 0, 10, 20, 50, 100, 150, or 200 μg a.i./ml of the fungicide. The plates were then incubated in the dark at 75 degrees F for 12 h. The percentage of germinated sporangia was determined by examining 100 sporangia per plate using light microscopy.

A sporangial suspension in SDW was prepared and incubated at 68 degrees F for 1 h to allow the sporangia to release their zoospores. Zoospores were separated from the empty sporangia by passing the liquid through a 4-layer facial tissue. Zoospores in SDW were induced to encyst by vortexing for 5 min. Concentration of zoospores was adjusted to 105 zoospores/ml. Aliquots (400 μl) were pipetted onto LBA plates amended with fungicides as described above. Inoculated plates were incubated in the dark at 75 degrees F for 12 h. The percentage of zoospore germination was assessed by examining 100 zoospores per plate using light microscopy.

Greenhouse studies. Effects of mefenoxam and metalaxyl on seedling damping-off of pumpkin, caused by P. capsici, were studied in a greenhouse using a naturally infested soil and artificially infested soil mix (field soil:sand; 3:1). Naturally infested soil was collected from a processing pumpkin field near Pekin, IL. The inoculum density of P. capsici in naturally infested field soil and artificially infested soil mix was determined by the soil dilution-plate method using a Phytophthora selective medium (PARPH). The inoculum density in the naturally infested field soil was 90 cfu/g soil, and the inoculum densities in artificially infested soils were 600, 1400, and 4000 colony forming unit (cfu)/g soil.

Seeds of three processing pumpkin cultivars (Dickinson, Hybrid-401, Hybrid-698) were treated with mefenoxam (0.64 fl oz Apron XL LS/100 lb seed) and metalaxyl (1.5 fl oz Allegiance LS/100 lb seed). A volume of tap water equivalent to 20% of seed weight was poured into a plastic bag and the fungicide was added to the water and mixed thoroughly. Seeds were placed in the bag and shaken for 2 min to coat the seeds with fungicide. Treated seeds were then air-dried.

Plastic pots (30-cm long × 20-cm wide × 15-cm deep) were filled with P. capsici-infested soil. Pots with non-infested soil were included as a control. Eighteen seeds were sown in each pot. The pots were arranged in a randomized complete block design, with three replications. All experiments were repeated twice. The experiments were conducted in a greenhouse maintained at 64-72 degrees F and pots were watered daily beginning the first day of seeding. Seedling emergence was assessed 10 days after sowing seeds and seedling stand was determined three weeks after seedling emergence (31 days after seeding). Diseased seedlings were examined using light microscopy and infected tissues were plated on PARPH for isolating P. capsici.

Field studies. Field experiments were conducted in irrigated pumpkin fields, naturally infested with P. capsici, near Pekin, IL, during 2001-2003. The experiments were performed in a randomized complete block design with three replications, each consisting of a 25-foot-long row. The plots were spaced 3 feet apart. Fifty seeds were planted in a single row in each plot. Seeds, either treated with mefenoxam (0.64 fl oz Apron XL LS/100 lb seed), metalaxyl (1.5 fl oz Allegiance LS/100 lb seed), or not treated (control), were sown approximately 5 cm deep. Soil samples were collected from the upper 10 cm of soil in the fields (one sample per 11 ft2 area, taken randomly), at the time of planting, using a soil auger, and mixed together. The population density of P. capsici was determined by dilution plating of soil samples on a PARPH selective medium and was ≥100 cfu per g soil. The seedlings were also sprayed with a P. capsici zoospore suspension (105 spores/ml; 150 ml/25 ft2 area) one week after seedling emergence to provide higher inoculum pressure in the plots. Application of foliar inoculum was to evaluate the efficacy of seed treatment on protecting plants against air-borne inoculum of P. capsici.

Seedling emergence was assessed 10 days after sowing seeds and seedling stand was determined 25 days after seedling emergence (35 days after seeding). Post-emergence damping-off was determined by counting plants showing girdling stem lesions with or without falling-over, wilting, and/or death of seedlings. Diseased seedlings were examined using light microscopy and infected tissues were plated on PARPH to isolate P. capsici.

Calcium application

Calcium on pumpkin and watermelon. Field trials were conducted during 2004-2004 to evaluate the effectiveness of calcium application, calcium application plus seed treatment, red-light treatment plus calcium application plus applications of a cooper fungicide (Cuprofix DF), and calcium application plus seed treatment plus application of fungicide Cuprofix DF for control of Phytophthora blight of pumpkin and watermelon. Processing pumpkin cultivar Dickinson and watermelon cultivar Royal Sweet were used in this study. The experiments were conducted in irrigated pumpkin fields near Pekin, IL. The fields, naturally infested with P. capsici, were planted in May and harvested in September. Seeds were treated with Apron XL LS (0.64 fl oz per 100 lb seed) prior to planting. For red light treatment, seedlings were grown under continues red light for four weeks in the greenhouse and transplanted into the plots.

Gypsum at the rate of 800 lb calcium per acre was applied at planting seed. Calcium chloride at the rate of 40 lb calcium per acre (one half at first female flower set and another half at fruit sizing) was applied. Calcium content of leaves in the plots with calcium application and in untreated control plots was determined. To determined calcium content of leaves, fully expanded leaves, closest to the vine growing tips, were collected at the growth stages of fruit set and one week before harvest and tested. Samples were digested in boiling HNO3, with sequential addition of 30% H2O2. Calcium content in each sample was determined by atomic absorption spectroscopy (AAS). To determine calcium content in soil, samples of soil were collected prior to application of Ca into soil. Soil samples were collected from top 0-8 inches. Samples were extracted with 1 N ammonium acetate (NH3OAc) with pH of 7.0 and determined by atomic absorption spectroscopy (AAS).

Disease incidence and severity on leaves, vines, and fruit were assessed at biweekly intervals beginning one week after seeding until harvest.

Calcium on pepper. Field trials were conducted during 2003-2004 to evaluate the effectiveness of calcium application, red-light treatment plus calcium application, and red-light treatment plus calcium application plus application of fungicide Cuprofix for control of Phytophthora blight of pepper. The experiments were conducted in an irrigated field near Pekin, IL. The field was naturally infested with P. capsici. Bell pepper cultivar California Wonder, a highly susceptible cultivar to P. capsici, was used in this study. Seedlings were grown in a greenhouse and eight-week-old seedlings were transplanted into the field.

Gypsum at the rate of 800 lb calcium per acre was applied at planting seedlings. Calcium chloride at the rate of 40 lb calcium per acre (one half prior to fruit set and another half three weeks after fruit set) was applied onto plants. Calcium content of leaves and soil was determined as described above. Disease incidence was determined as percent wilted or dead plants on a weekly schedule one week after transplanting until the end of the season.

Screening pumpkin and pepper cultivars/lines for resistance to P. capsici

Screening pumpkins. Six processing pumpkin cultivar and 22 jack-o-lantern pumpkin cultivars were screened for resistance to P. capsici. Plants were grown in the greenhouse and four-week-old seedlings were inoculated by adding 5 ml of a zoospore suspension (2 x 105 spores/ml of water) onto the soil surface around the stem of each plant in the pot. Disease development on the plants was assessed daily until 21 days after inoculation.

Screening peppers. Sixty-eight cultivars/lines of bell pepper were evaluated for resistance against P. capsici in the greenhouse and field. Seedlings were grown in a greenhouse at 64 to 77 degrees F. Eight-week-old seedlings were inoculated with P. capsici by adding 5 ml of zoospore suspension in SDW (2 x 105 spores/ml) at the base of each seedling. Control seedlings were treated with only SDW.

The pots were watered before inoculation to keep the soil wet. After inoculation, the pots were watered three times per day. Beginning the 4th day after inoculation, seedlings were evaluated for development of Phytophthora lesions on the lower section of stems, loosing leaves, wilting, and death of the seedlings. The evaluation of disease development on the seedlings was continued until 24 days after inoculation, when no more infection was observed.

Cultivars/lines, that showed resistant to P. capsici in the greenhouse trials, were tested in field trials. California Wonder, Arthur King, and Maxi Bell, susceptible bell pepper cultivars to P. capsici, were included in the field trials as control checks.

Host range of P. capsici. This study was conducted to determine the host range of P. capsici isolates from pumpkin. The pathogenicity of P. capsici isolates from pumpkin was evaluated on 45 species of herbaceous plants, including 36 species of crops grown in rotation sequences with pumpkin and nine species of weeds that commonly grow in pumpkin fields in Illinois. Plants were grown in the greenhouse and four-week-old seedlings were inoculated by adding 5 ml of a zoospore suspension (2 x 105 spores/ml of water) onto the soil surface around the stem of each plant in the pot. Disease development on the plants was assessed daily until 22 days after inoculation.

Fungicide application. More than 35 fungicides, with potential in controlling Phytophthora diseases, were tested in the laboratory and field for controlling Phytophthora blight and fruit rot of pumpkin, watermelon, and pepper, caused by P. capsici. Fungicides were tested in the laboratory at concentrations of 5 to 100 ppm active ingredient (a.i.) and in the field at recommended rates by the manufacturers.

For pumpkin and watermelon, field experiments were conducted in both irrigated and non-irrigated fields near Pekin, IL, naturally infested with P. capsici. Seeds of the pumpkin cultivar Dickinson and watermelon cultivar Royal Sweet were used in the studies. Soil-drenching fungicides were applied at planting. Foliar-applications of fungicides were made at weekly intervals starting from 2nd, 3rd, 4th, and 5th week after planting at weekly intervals. The fungicides were applied with a backpack sprayer using 50 gallons of water per acre. Plants were examined on biweekly intervals for symptoms of damping-off, Phytophthora foliar blight, and fruit rot beginning second week after planting seeds until harvest. Disease incidence and severity on leaves and vines were evaluated at three locations (11 ft 2 each) in each plot. Ten fruits were examined in each plot for Phytophthora infection. Disease incidence was determined as percent leaves, vines, or fruits affected. Disease severity was determined as percent area of leaf or vine affected. Also, numbers of uninfected and infected fruit with P. capsici were recorded at the harvest. Weight of uninfected fruit was measured. The data were analyzed using GLM procedures of SAS.

For pepper, field experiments were conducted in commercial fields, infested with P. capsici. near Shawneetown (southern Illinois) and near Pekin (central Illinois) to evaluate the effectiveness of selected fungicides for control of Phytophthora blight. Seedlings of bell pepper cultivar California Wonder, highly susceptible to P. capsici, were grown in a greenhouse. Eight-week-old seedlings were transplanted into raised beds with drip irrigation and black plastic mulch. Application of fungicides began second week after transplanting. Fungicides were applied with a backpack sprayer, using 50 gallons of water per acre. Disease incidence was determined as percent wilted or dead plants on a weekly schedule.

Commercial names of tested fungicides on pumpkin, watermelon, and pepper were: A1662 480SC, Acrobat 50WP, Acrobat MZ, Actigard 50WG, AgriFos 400FL, Aliette 80WDG, Apron XL LS, ATOFAP, Bravo Ultrex 82.5WG, Cuprofix 20DF, Cuprofix 40DF, Curzate 60DF, DPX-GFJ52 46.1WG, Forum 4.16SC, Gavel 75DF, Kocide-2000, Manex 37F, NOA-446510 250SC, Nova 40W, Omega 500F, Pencozeb75DF, Phostrol 53.5F, Previcur Flex 66.5F, Pristine 38WG, ProPhyt 4.2F, Quadris 2.08SC, Ranman 400SC, Reason 500SC, Ridomil Gold Bravo, Ridomil Gold Copper, Ridomil Gold EC, Ridomil Gold MZ, Silwet L-77, Tanos 50WG, TD-2389-02, and USF-2001 520SC.

Research results and discussion:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Results and Discussion/Milestones

Characteristics of P. capsici isolates in Illinois. Isolates tested exhibited four growth patterns in cultures: cottony, rosaceous, petaloid, and stellate. P. capsici isolates, including an isolate form the American Type Culture Collection (ATCC-15427), with cottony growth pattern did not grow at 97 degrees F. All isolates produced papillate and deciduous sporangia on long pedicels that were mostly ellipsoid to ovoid. The mean length of sporangia among the isolates ranged from 42.2 to 55.4 µm, and mean breadth of sporangia varied from 24.0 to 39.1 µm. The length/breadth ratio of sporangia ranged from 1.3 to 1.8 among the isolates. Mean pedicel length ranged from 34.3 to 101.4 µm. All 57 isolates of P. capsici tested were heterothallic. Thirty-one isolates were A1 mating type and 26 isolates were A2 mating type. The mean oospore diameter of A1 mating type isolates was greater than that of A2 mating types. Nine of 24 isolates tested produced chlamydospores in V8-CaCO3 liquid medium. Unweighted mean pair group analysis clustered isolates into six groups. The genetic distances ranged from 0.03 to 0.45. Inoculation of pumpkin seedlings in the greenhouse revealed that the isolates belonging to six distinct genetic groups differing significantly (P = 0.05) in virulence.

Red-light treatment. Red-light treatment of seedlings reduced Phytophthora damping-off by up to 79% in the greenhouse trials. Only 21 to 36% of red light treated seedlings became infected, whereas 78 to100% of the control seedlings, grown either in natural daylight (NDL) or under white light (WL), became infected and died. The height, fresh and dry weight of seedlings treated with red light were significantly higher than those grown under NDL or WL.

Experiments on optimization of red-light treatment for control of P. capsici showed that red-light irradiation at night induced an equal or higher degree of plant resistance against P. capsici than continuous red-light irradiation (day and night). Thirty days post-inoculation, 60-85% of pepper, tomato, and pumpkin seedlings that received red-light at night remained uninfected. Red-light irradiation during daytime was not effective in inducing plant resistance. The seedling survival for those receiving continuous red-light irradiation (day and night) or daytime-only irradiation, were 60-75% and 6-40%, respectively. In controls (grown under natural day light), 75-100% of seedlings became infected and died within 15 days of inoculation. Doubling the red-light intensity induced greater resistance in pepper seedlings but had the opposite effect in tomato.

In the field trials, red-light treatment of seedlings of pepper, tomato, and watermelon delayed occurrence of plant infection with P. capsici, but did not provide season-long protection of plants against the pathogen. It was concluded that red-light treatment is very effective in controlling plant diseases in greenhouses, but further studies are needed to determine its effectiveness against P. capsici in the fields.

Seed treatment. Apron XL LS (mefenoxam) and Allegiance LS (metalaxyl) were highly inhibitory to growth of mycelium of P. capsici in vitro. ED50 of mefenoxam and metalaxyl for inhibition of mycelial growth, for all five isolates of P. capsici tested, was 0.98 and 0.99 μg a.i./ml of culture medium, respectively. At 200 μg a.i./ml of mefenoxam, sporangium and zoospore germination were reduced by 92 and 96%, respectively; zoospore germination was reduced by 21 and 24%, respectively, for metalaxyl. In greenhouse studies, seed treatment with mefenoxam (0.64 fl oz Apron XL LS/100 lb seed) and metalaxyl (1.5 fl oz Allegiance LS/100 lb seed) significantly reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars, Dickinson, Hybrid-401, and Hybrid-698, tested. Thirty-one days after seeding, at inoculum levels of 0, 90, 600, 1400, and 4000 cfu/g soil, the average seedling stands for mefenoxam treatment were 98.4, 93.8, 88.3, 77.8, and 64.8%; for metalaxyl, were 99.1, 85.3, 85.8, 73.5, and 59.3; and for the untreated control were 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after seeding were 76.7, 74.7, and 44.9% for mefenoxam, metalaxyl, and untreated control, respectively. Seed treatment with mefenoxam or metalaxyl did not have any significant effect on either seed germination or seedling vigor.

Calcium application. The incidence of foliar infection in the pumpkin, watermelon, and pepper plots that received soil and foliar applications of calcium was significantly lower than that of control plots. However, calcium application (soil and/or foliar) alone did not provide satisfactory season-long protection of plants against P. capsici. Also, the incidence of fruit infection in the treated plots with calcium plus copper compound (Cuprofix DF) was significantly lower than that of untreated plots. Integration of seed, red-light treatment, and calcium application did not provide satisfactory season-long protection of plants against P. capsici. Integration of seed treatment, calcium application, and spray application of Cuprofix DF was effective in protecting plants against P. capsici. Further investigation on integrations of red-light treatment and calcium application or red-light treatment/calcium application/spray application of Cuprofix DF may provide additional result for effective control of Phytophthora blight in pepper fields.

Screening pumpkin and pepper cultivars/lines for resistance to P. capsici
Screening pumpkins. None of the processing or jack-o-lantern pumpkin cultivars tested was found resistance to the Illinois isolates P. capsici, which is in agreement with previous reports that none of the cucurbit cultivars has measurable resistance to P. capsici.

Screening peppers. The following cultivars/lines were found resistance to P. capsici in the greenhouse and field trials: Abbott – 1, Abbott – 2, Abbott – 13, Alliance, Aristotle, BHN-1P, BHN-2P, Emerald Isle, Enzaq- 9006, Paladin, Reinger, Revolution, and Syngenta – 7326. Presently, the following cultivars are recommended as resistant bell pepper cultivars against P. capsici: Paladin (highly resistant), Rainger (highly resistant), Emerald Isle (intermediate resistant), Revolution (intermediate resistant), Aristotle intermediate resistant), and Alliance (somewhat resistant).

Host range of P. capsici. Plants of 22 crop species and two weed species exhibited damping-off symptoms. Plants of 14 crop species and seven weed species did not develop any symptoms. All plants from Cucurbitaceae and Solanaceae, and most of the plants from Chenopodiaceae, families became infected and developed symptoms. Cucurbits and pepper were the most susceptible to the Illinois isolates of P. capsici, as more than 50% and 95% of their seedlings became infected and developed symptoms within three and 12 days after inoculation, respectively. Infection in

beet, carrot, eggplant, green bean, lima bean, nightshade, radish, snow pea, spinach, Swiss chard, tobacco, tomato, turnip, and velvetleaf developed symptoms slowly. However, more than 50% of the seedlings of these crops developed symptoms within 12 days from inoculation. Onion was less susceptible and only 41.9% of its seedlings exhibited symptoms. No obvious changes in symptoms development was observed after 12 days post inoculation. P. capsici was reisolated from all of the symptomatic plants on PARP culture medium. Using the PCR method, P. capsici was detected in all symptomatic plants with exception of beet, snow pea, and Swiss chard. We were unable to detect P. capsici in these species by the PCR method for reasons unknown. None of the control plants developed disease symptoms and attempts to isolate P. capsici from their tissues were unsuccessful.

Basil, broccoli, cabbage, cauliflower, celery, chive, corn, dill, kale, kohlrabi, mustard, parsley, soybean, and wheat seedlings did not develop any symptoms. Likewise, the weed species of cocklebur, crab grass, lamb’s-quarters, pigweed, puncture vine, sandbur, and water hemp did not develop symptoms. Attempts to re-isolate P. capsici from asymptomatic plant tissues of inoculated plants, or detect the pathogen by the PCR method, did not provide any indication of presence of P. capsici in these plants.

Fungicide application. Following fungicides have been found effective against Illinois isolates of P. capsici: Acrobat 50WP (dimethomorph), Forum 4.16SC (dimethomorph), Tanos 50WG (famoxadone + cymoxanil), ProPhyt 4.2F (phosphorus acid), Apron XL LS (mefenoxam), Ridomil Gold EC (mefenoxam), Ranman 400SC (cyazofamid), Cuprofix DF (copper sulfate), Kocide-2000 (copper hydroxide), and Gavel 75Df (zoxium). More fungicides are being tested to evaluate their effectiveness against P. capsici. Among the tested fungicides, the most effective fungicide against Illinois isolates of P. capsici was dimethomorph (Acrobat 50WP, Forum 4.16SC). The second most effective fungicide for control of Phytophthora blight of cucurbits and peppers in Illinois was Tanos 50WG (famoxadone + cymoxanil). Either Forum (or Acrobat) or Tanos should be mixed with a copper compound (Cuprofix DF, Kocide-2000, or Champ) and applied at a weekly intervals. Application of Forum (or Acrobat) plus a copper compound can be alternated with Tanos plus a copper compound for control of P. capsici.

Research conclusions:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Impact of the Results/Outcomes

Illinois grows about 20,000 acres of pumpkin and 10,000 acres of cucumbers, eggplants, cantaloupe, peppers, squash, tomatoes, and watermelons. More than 90% of commercial processing pumpkins are produced and processed in Illinois. Also, the North Central region produces more than 130,000 acres of these crops. Phytophthora blight, caused by P. capsici, is a serious threat to production of these crops in the regions as well as nationwide. Because of heavy crop losses to Phytophthora blight during 1998-2000, processing pumpkin industry was thought to be abandoned in Illinois. Due to the findings of this project not only the processing pumpkin industry was not abandoned in Illinois, but also its acreage was increased from about 6,000 acres in 1998 to more than 10,000 acres in the past years. Similarly, production of jack-o-lantern pumpkins, squashes, and peppers in Illinois has increased. Using integrated approaches to control Phytophthora blight in cucurbits and pepper fields, no more than 10% crop losses have occurred in commercial fields in Illinois during the past four years. Based on the communication with producers, agribusiness personnel, and extension specialists, and invited presentations at national/international levels in the past three years, the impact of results/outcomes of this project on understanding and management of Phytophthora blight, caused by P. capsici, has been enormous. Presently, University of Illinois is considered one of the leading institutes in conducting problem-solving research on Phytophthora blight of vegetables, caused by P. capsici.

Economic Analysis

New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Economic Analysis

P. capsici attacks to more than 50 crops, including cucurbits (cucumber, melons, pumpkins, squashes), eggplant, and peppers, causing up to 100% crop losses. Farm-gate values of these crops are more than $3,000 per acre, some exceeding $5,000 per acre. Currently Illinois grows approximately 10,000 of processing pumpkins. The gross values of the products of processing pumpkin can exceed $10,000 per acre. Thus, these crops are high-value/cash crops and have substantial economic, educational, and social impact in Illinois, as well as nationwide. Growing varieties of peppers resistant to Phytophthora blight, caused by P. capsici, has no additional disease management costs. The cost for production of pepper seedlings under red light in the greenhouses may not exceed $1 per square foot. Full-season production of pepper crops in greenhouse under red-light yet to be figured out. Seed-treatment of cucurbits with mefenoxam (Apron XL LS) costs approximately $0.02 per acre (negligible). Each spray-application of fungicides (e.g., Acrobat/Forum plus a copper compound) in cucurbit or pepper commercial fields costs approximately $15 per acre. So, control of Phytophthora blight in one acre of processing pumpkin field (also other cucurbit fields) may include the following costs: $0.02 for seed treatment, $5 for scouting the field throughout the growing season, and $15 per spray per acre. One to three fungicide sprays are usually applied in pumpkin fields with Phytophthora blight during a growing season. If the weather conditions are conducive for development of Phytophthora blight, up to five fungicide-spray applications may be needed to effectively control the Phytophthora blight. But, the total cost for controlling Phytophthora blight in cucurbits and pepper fields should not exceed $80 per acre per season, which is insignificant when it is compared to the values of the crops. Cucurbits and pepper industries in Illinois provides seasonal and year-round jobs to thousands of people. Thus, abandoning processing pumpkin and other vegetable production in Illinois, because of heavy crops losses to Phytophthora blight, caused by P. capsici, would have serious economical and social impact in the agricultural communities in the state. Similarly, economical impacts of Phytophthora blight, caused by P. capsici, on vegetable industries in the North Central region is very important. Cucurbits have been identified the most important vegetable crops in the North Central region and Phytophthora is considered the most serious threat to cucurbits industries in the region.

Farmer Adoption

New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Farmer Adaptation

Farmers have widely adapted the findings of this project. Cucurbit growers, especially pumpkin growers, are using seed treatment, developed in this research, to control seedling death of cucurbit crops, caused by P. capsici and other oomycete pathogens. Growers are able to effectively control Phytophthora blight in cucurbit fields by application of effective fungicides identified in this study. The integration of seed treatment, disking localized area with infected plants, and spray application of fungicides for control of the Phytophthora blight is widely practiced in commercial cucurbit field, particularly in processing pumpkin fields. Pepper growers have options of either planting identified resistant varieties, if they are commercially acceptable, or application of fungicides to control Phytophthora blight.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:
New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Publications/Outreach

Publications (chronological list)

1. Babadoost, M., and Islam, S.Z. 2003. Effects of fungicide seed treatment on seedling death of pumpkin caused by Phytophthora capsici. 2003 Processing Crops Manual and Proc. Midwest Food Processors Association: 139-142.

2. Babadoost, M. 2003. Phytophthora foliar blight and fruit rot of cucurbits. The Specialty Grower News, March 2003: 19-20.

3. Babadoost, M., and Islam, S.Z. 2003. Fungicide seed treatment effects on seedling damping-off of pumpkin caused by Phytophthora capsici. Plant Dis. 87:63-68.
4. Tian, D., and Babadoost, M. 2003. Determining the host range of Phytophthora capsici in Illinois. Phytopathology 93:S83. Publication no. P-2003-0612-AMA.

5. Babadoost, M. 2003. Phytophthora blight of vegetables. Illinois Fruit and Vegetable News, Volume 9, Number 11:3-4.

6. Islam, S.Z., Babadoost, M., Swiader, J.M., and Walters, S.A. 2003. Effects of fungicides and calcium applications on Phytophthora blight of pumpkin caused by Phytophthora capsici. 3rd Annu. Illinois Fruit and Vegetable Crop Res. Rep. pp. 22-27.

7. Tian, D., and Babadoost, M. 2004. Host Range of Phytophthora capsici from Pumpkin and Pathogenicity of Isolates. Plant Dis. 88:485-489.

8. Babadoost, M. 2004. Control of Phytophthora blight of bell pepper with fungicides, 2003. Fung. & Nemat. Tests 59:V131.

9. Islam, S.Z., and Babadoost, M. 2004. Evaluation of selected fungicides for control of Phytophthora blight of processing pumpkin, 2003. Fung. & Nemat. Tests 59:V129.

10. Babadoost, M. 2004. Phytophthora blight: A serious threat to cucurbit industries. http://www.apsnet.org/online/feature/cucurbit/.

11. Babadoost, M. 2004. Phytophthora blight of cucurbits: how to manage it? Illinois Fruit and Vegetable News, Volume 10, Number 7:9-10.

12. Babadoost, M., and Islam, S.Z. 2004. Methods for managing Phytophthora blight (Phytophthora capsici) of pepper. The 17th International Pepper Conference, November 14-16, Naples, Florida. Page 1, Abstract of papers, 33 pp.

13. Babadoost, M., and Islam, S.Z. 2004. Fungicide for control of Phytophthora blight (Phytophthora capsici) of vegetables. Phytopathology 95-S5.

14. Islam, S.Z., and Babadoost, M. 2004. Optimization of red-light irradiation in inducing resistance in vegetable seedlings against Phytophthora capsici. Phytopathology 95:S44.

15. Babadoost, M., and Islam, S.Z. 2004. Bell Pepper Evaluation for Resistance to Phytophthora Blight. Midwest Veg. Var. Tests. Page 43.

16. Babadoost, M., S.Z., Islam, J.M., Swiader, and S.A., Walter, 2004. Efficacy of fungicides and calcium applications for control of Phytophthora blight of processing pumpkin in 2004. IL Fruit Veg. Res. Report, 2004:44-50.

17. Babadoost, M. 2004. Phytophthora blight of cucurbits. 4 pp (Extension Bulletin).

18. Babadoost, M., and Islam, S.Z. 2005. Evaluation of fungicides for control of Phytophthora blight of bell pepper, 2004. Fung. & Nemat. Tests 60:V055.

19. Islam, S.Z., and Babadoost, M. 2005. Fungicide evaluation for control of Phytophthora blight of processing pumpkin, 2004. Fung. & Nemat. Tests 60:V054.

20. Babadoost, M. 2005. Phytophthora blight: a serious concern for vegetable growers. Pp 1-4. In Proceedings of Field Tomato and Pepper Session, Ontario Fruit and Vegetable Convention and Trade Show, February 16 & 17, 2005, Brock University, St. Catherines, Ontario, Canada.

21. Islam, S.Z., Babadoost, M., Lambert, K., Ndeme, A., and Fouly, H.M. 2005. Characterization of Phytophthora capsici isolates from processing pumpkin in Illinois. Plant Dis. 89:191-197.

22. Babadoost, M., and Islam, S.Z. 2005. An integrated approach for management of Phytophthora blight (Phytophthora capsici) of cucurbits. Phytopathology 95 (June supplement): S4.

23. Islam, S.Z., and Babadoost, M. 2005. In Vitro evaluation of antifungal activity of an isolate of Streptomyces sp. against soil-borne pathogens. Phytopathology 95 (June supplement): S47.

24. Pavon, C., and Babadoost, M. 2005. Extraction and enumeration of Phytophthora capsici oospores in soil. Phytopathology 95 (June supplement): S81.

25. Babadoost, M., Islam, S.Z., Tian, D., and Pavon, C. 2005. Phytophthora blight (Phytophthora capsici) of peppers in Illinois: occurrence and management. Pages 7-12, In Proceedings of the Second World Pepper Convention, Zacatecas, Mexico, August 14-16, 2005.

26. Babadoost, M. 2005. Phytophthora blight of cucurbits. The Plant Health Instructor. DOI:10.1094/PHI-I-2005-0429-01.

27. Babadoost, M., and Islam, S.Z. 2005. Field evaluation of bell peppers for resistance to Phytophthora blight (Phytophthora capsici), 2005. Pages 47-50 in 9th Annual Illinois Fruit and Vegetable Research Report.

28. Babadoost, M. 2006. Efficacy of selected fungicides for control of Phytophthora blight of bell pepper, 2005. Fung. & Nemat. Tests 61: V022.

29. Babadoost, M., and Islam, S.Z. 2005. Fungicide evaluation for control of Phytophthora blight of processing pumpkin, 2005. Fung. & Nemat. Tests 61: V023.

30. Babadoost, M., Swiader, J.S., and Islam, S.Z. 2006. To develop and implement effective tactics for management of Phytophthora blight of vegetables. Pages 2-3. In USDA-CSREES, North Central Region Integrated Pest Management Grants Program.

31. Babadoost, M., Islam, S.Z., Pavon, C., and Tian, D. 2006. Strategies for management of Phytophthora blight (Phytophthora capsici) of cucurbits. 5th National Integrated Pest Management Symposium, April 4-6, 2006, St. Louis, Missouri. Abstract of papers: P084, page 83.

Outreach

The following are outreach activities in relation to this project.

2003

• State/Regional Presentations

1. Pumpkin disease updates (Illinois Specialty Growers meeting, Champaign, IL, January, 2003).

2. Management of pumpkin diseases (Vegetable School, Mt. Vernon, IL, February, 2003).

3. Important vegetable diseases (emphasizing cucurbit diseases) (Kankakee, IL, February, 2003.

4. Cucurbit crisis in northeast Illinois (growers and extension personnel, University of Illinois, Champaign, IL, August, 2003).

5. Pumpkin Field Day (first pumpkin field day of Illinois, Champaign, IL, September 2003).

• National Presentations

1. Determining the host range of Phytophthora capsici in Illinois (APS meeting, Milwaukee, WI, August, 2003).

2. Genetic variation among isolates of Phytophthora capsici from Illinois (APS meeting, Milwaukee, WI, August, 2003).

• Invited Presentations

1. Vegetable disease diagnosis (Dept. of Horticulture, Univ. of Missouri, Columbia, MO. July, 2003).

• Website
http://veg-fruit.cropsci.uiuc.edu

2004

• State/Regional Presentations

1. Emerging vegetable diseases (Schererville, IN, January, 2004).

2. Vegetable disease management (emphasizing cucurbit diseases) (Illinois Specialty Growers meeting, Springfield, IL, January, 2004).

3. Managing vegetable diseases (emphasizing cucurbit diseases) (Kankakee, IL, February, 2004).

4. Updates on vegetable diseases in Illinois (Vegetable School, Mt. Vernon, IL, February, 2004).

5. New fungicides for vegetable crops (Vegetable School, Mt. Vernon, IL, February, 2004).

6. Important cucurbit diseases (Delavan, WI, February, 2004).

7. Pumpkin diseases (second pumpkin field day of Illinois, St. Charles, IL, September, 2004).

8. Emerging vegetable diseases in Illinois (UI Agronomy Day, Champaign, IL, August, 2004).

9. Dying on the vine (Moline, IA, November, 2004).

• National Presentations

1. Fungicide for control of Phytophthora blight (Phytophthora capsici) of vegetables (APS meeting, Salt Lake City, UT, August, 2003).

2. Optimization of red-light irradiation in inducing resistance in vegetable seedlings against Phytophthora capsici(APS meeting, Salt Lake City, UT, August, 2003).

3. Methods for managing Phytophthora blight of peppers (The 17th International Pepper Conference. Naples Beach Hotel & Golf Club, Naples, FL, November, 2004).

• Invited Presentations

1. Effectiveness of Tanos fungicide for control of cucurbit diseases (DuPont, Inc., Newark, DE. April, 2004).

2005

• State/Regional Presentations

1. Pumpkin disease management (Illinois Specialty Growers meeting, Springfield, IL, January, 2005).

2. Vegetable diseases in Illinois (Vegetable School, Mt. Vernon, IL, February, 2005).

3. Soil-borne diseases of cucurbits (Vegetable School, Mt. Vernon, IL, February, 2005).

4. Vegetable disease management (Amish School, Arthur, IL, March, 2005).

5. Pumpkin diseases (North Central Pumpkin IPM, Urbana, IL, August, 2005).

6. Vegetable production in Illinois (UI Agronomy Day, Champaign, IL, August, 2005).

7. Pumpkin diseases (third pumpkin field day of Illinois, St. Charles, IL, September, 2005).

• National Presentations

1. Extraction and Enumeration of Phytophthora capsici oospores from soil (APS meeting, Austin, TX, August, 2005).

2. In vitro evaluation of antifungal activities of an isolate of Streptomyces sp. against soil-borne pathogens (APS meeting, Austin, TX, August, 2005).

• Invited Presentations

1. Phytophthora Blight of Cucurbit: Importance and Management (Ontario Vegetable Processing Industry Conference, London, Ontario, Canada, January, 2005).

2. Progress in managing Phytophthora blight of vegetables caused by Phytophthora capsici (Phytophthora capsici workshop, Little Rock, AR, February, 2005).

3. Phytophthora blight (Phytophthora capsici) of pepper (3rd Annual Ontario Fruit and Vegetable Convention, St. Clair, Ontario, Canada, February 16-17, 2005).

4. Vine crop diseases: effective management (3rd Annual Ontario Fruit and Vegetable Convention, St. Clair, Ontario, Canada, February 16-17, 2005).

5. Management of Phytophthora Blight (Phytophthora capsici) of Cucurbits and Peppers: Progress and Frustration (University of Wageningen, Wageningen, the Netherlands, July, 2005.

6. Phytophthora Blight (Phytophthora capsici) of Pepper in Illinois: Occurrence and Management (Second World Pepper Convention, Zacatecas, Mexico, August, 2005).

7. Importance of Phytophthora Blight of Peppers – a Team Presentation/Discussion (Second World Pepper Convention, Zacatecas, Mexico, August, 2005).

8. Importance and Management of Phytophthora Blight (Phytophthora capsici) of Vegetables (Plant Pests and Diseases Research Institute, Tehran, Iran, November, 2005).

9. Importance and Management of Phytophthora Blight (Phytophthora capsici) of Vegetables (College of Agriculture, University of Tabriz, Tabriz, Iran, November, 2005).

10. Managing Phytophthora Blight (Phytophthora capsici) of Vegetables (International Symposium on Food Health and Wellness. Universidad Autonoma de Aguascalientes, Mexico, November, 2005).

11. Managing Phytophthora Blight (Phytophthora capsici) of Vegetables (International Symposium on Food Health and Wellness. Universidad Autonoma de Queretaro, Mexico, November, 2005).

2006

• State/Regional Presentations

1. Updates on disease management in vine crops (Illinois Specialty Growers meeting, Springfield, IL, January, 2006).

2. Managing pepper diseases (Mt. Vernon, IL, February, 2006).

3. Managing cucurbit diseases (Delavan, WI, February, 2006).

4. Major vegetable diseases in the area and their control (Vegetable School, Kankakee, IL, February, 2006).

5. Phytophthora blight of cucurbits and peppers: occurrence and management (Great Lake Vegetable Working Group, East Lansing, MI, February, 2006).

• National Presentations

1. Chemical control of Phytophthora capsici in vegetables (Soil Fungus Conference, Reno, NV, April, 2006).

2. Strategies for management of Phytophthora blight (Phytophthora capsici) of cucurbits (5th National Integrated Pest Management Symposium, St. Louis, MO, April, 2006).

3. Fourth Pumpkin Day has been scheduled at Champaign, IL, for September 8, 2006.

• Invited Presentations

1. Disease control on cucurbits (Muck Crop School, Ohio State University, Willard, OH, January, 2006).

2. Managing Phytophthora blight in pepper (Muck Crop School, Ohio State University, Willard, OH, January, 2006).

3. Fungicide evaluation for control of Phytophthora blight of pumpkin and pepper in Illinois (Phytophthora capsici workshop, Orlando, FL, March, 2006).

Project Outcomes

Recommendations:

Areas needing additional study

New Strategies for Management of Vegetable Diseases in Organic and Traditional Farms

Areas Needing Additional Study

Additional studies are needed to determine survival of the pathogen (P. capsici) in the soil for establishing effective cropping rotation systems. Investigating the ecology of the Phytophthora blight is also needed. A long-term research is needed to develop resistant varieties of cucurbits against P. capsici, either through conventional approaches or utilizing genetic-engineering methods.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.