Using Cultural Practices and Cultivar Resistance to Manage Phytophthora Crown Rot on Summer Squash

The effects of bed height, mulches, composted poultry litter, and cultivars on Phytophthora crown rot, caused by Phytophthora capsici Leonian, of summer squash (Cucurbita pepo L.) were evaluated in the absence of fungicide applications. The experimental design was a split-split-split plot arrangement of a randomized complete block. Bed height (flat or raised) was the main plot treatment. Mulches (bare soil, wheat straw, or plastic) were subplot treatments. Composted poultry litter applications (0 or 4.5 t·ha−1) were sub-subplot treatments. Squash cultivars (Cougar or Payroll) were sub-sub-subplot treatments. Incidence of plant death (%) was assessed from 0 to 35 days post-inoculation (dpi) with P. capsici. Plant death 35 dpi and area under the disease progress curve (AUDPC)differed significantly (P < 0.0001) between the cultivars Cougar and Payroll. Mean plant death 35 dpi was 87% for ‘Payroll’ and 99% for ‘Cougar’. The bed height × cultivar interaction was also significant (P = 0.0018) in the analyses of variance for plant death and AUDPC. Plant death at 35 dpi and AUDPC for ‘Payroll’ were greater in flat beds than raised beds. Disease was unaffected by the main effects of bed height, mulch type, or application of poultry litter. Thirty-two summer squash cultivars and 10 germplasm accessions were also evaluated for resistance to Phytophthora crown rot in a separate greenhouse trial. Crown rot severity was rated on a 1 (no symptoms) to 5 (plant death) scale at 18 dpi. Crown rot severity differed significantly (P < 0.0001) among cultivars and germplasm accessions. Crown rot severity averaged 4.3 on commercial cultivars and 2.2 on germplasm accessions. Crown rot was least severe on the commercial cultivar Spineless Beauty (mean rating = 2.9). No disease developed on four accessions of Cucurbita moschata previously reported to be crown rot-resistant.

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An Evaluation of Cucurbits for Susceptibility to Cucurbitaceous and Solanaceous Phytophthora capsici isolates

Plant Disease ◽

10.1094/pdis-09-11-0771-re ◽

2012 ◽

Vol 96 (10) ◽

pp. 1404-1414 ◽

Cited By ~ 9

Author(s):

T. B. Enzenbacher ◽

M. K. Hausbeck

Keyword(s):

Phytophthora Capsici ◽

Post Inoculation ◽

Progress Curve ◽

Crop Type ◽

Summer Squash ◽

Millet Seed ◽

Oomycete Pathogen ◽

Potting Media ◽

Phytophthora Rot ◽

Winter Squash

Cucumber (Cucumis sativus) and squash (Cucurbita spp.) production in Michigan is limited by the oomycete pathogen Phytophthora capsici. Cucumber, summer squash, and winter squash fruit were evaluated for susceptibility to five isolates of P. capsici. Detached fruit were inoculated with a 5-mm-diameter culture plug of mycelia and sporangia and were incubated in a laboratory or greenhouse. Lesion and pathogen growth diameters were measured and pathogen growth density was visually assessed. All P. capsici isolates incited rot, with significant differences found among fruit type and pathogen isolate. Straightneck squash (Cucurbita pepo), slicing cucumber, and butternut squash (C. moschata) exhibited more severe symptoms than the other fruit tested. Summer and winter squash seedlings were evaluated in greenhouse experiments, in which P. capsici-infested millet seed (approximately 1 g) were placed on the surface of soilless potting media. Disease severity was visually assessed every 2 days for 14 days post inoculation. Crop type, pathogen isolate, or the crop type–pathogen isolate interaction term were significant for symptom appearance and area under the disease progress curve values. Differences in susceptibility of butternut squash and zucchini cultivars were observed following inoculation with solanaceous isolate 13351. Results from this study can refine management programs for Phytophthora rot.

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Potential Sources of Resistance in U.S. Cucumis melo PIs to Crown Rot Caused by Phytophthora capsici

HortScience ◽

10.21273/hortsci.48.2.164 ◽

2013 ◽

Vol 48 (2) ◽

pp. 164-170 ◽

Cited By ~ 3

Author(s):

Ryan S. Donahoo ◽

William W. Turechek ◽

Judy A. Thies ◽

Chandrasekar S. Kousik

Keyword(s):

Cucumis Melo ◽

Phytophthora Capsici ◽

Crown Rot ◽

Fruit Rot ◽

Broad Host Range ◽

Post Inoculation ◽

Vegetable Crops ◽

Phytophthora Blight ◽

Sources Of Resistance ◽

Breeding Programs

Phytophthora capsici is an aggressive pathogen that is distributed worldwide with a broad host range infecting solanaceous, fabaceous, and cucurbitaceous crops. Over the past two decades, increased incidence of Phytophthora blight, particularly in eastern states, has threatened production of many vegetable crops. Cucumis melo L. (honeydew and muskmelon), although especially susceptible to fruit rot, is also highly susceptible to crown rot. Currently, little is known about host resistance to P. capsici in C. melo. To assess crown rot resistance in C. melo seedlings, 308 U.S. PIs, and two commercial cultivars (Athena and Dinero) were grown under greenhouse conditions. Seedlings with three to four true leaves were inoculated with a five-isolate zoospore suspension (1 × 104 zoospores per seedling) at the crown and monitored for 6 weeks. All the susceptible control plants of Athena died within 7 days post-inoculation. The majority of the PIs (281 of 308) were highly susceptible to crown rot and succumbed to the disease rapidly and had less than 20% of the plants survive. Several PIs (PI 181748, PI 182964, and PI 273438) succumbed to crown rot earlier than the susceptible melon cultivars. Eighty-seven PIs selected on the basis of the first screen were re-evaluated and of these PIs, 44 were less susceptible than cultivars Athena and Dinero. Twenty-five of the 87 PIs were evaluated again and of these six PI, greater than 80% of the plants survived in the two evaluations. Disease development was significantly slower on these PIs compared with the susceptible checks. High levels of resistance in S1 plants of PI 420180, PI 176936, and PI 176940 were observed, which suggests that development of resistant germplasm for use in breeding programs can be accomplished. Further screening and careful selection within each of these PIs can provide a framework for the development of resistant germplasm for use in breeding programs.

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Diethatyl for Hairy Galinsoga (Galinsoga ciliata) Control in Peppers (Capsicum annuum) Integrated with Cultural Practices for Phytophthora Blight Control

Weed Science ◽

10.1017/s0043174500067448 ◽

1986 ◽

Vol 34 (4) ◽

pp. 569-571 ◽

Cited By ~ 2

Author(s):

Bradley A. Majek ◽

Stephen A. Johnston

Keyword(s):

Capsicum Annuum ◽

Surface Soil ◽

Cultural Practices ◽

Phytophthora Capsici ◽

Crown Rot ◽

Yield Reduction ◽

Phytophthora Blight ◽

Untreated Soil ◽

And Control ◽

Galinsoga Ciliata

Diethatyl [N-(chloroacetyl)-N-(2,6-diethylphenyl) glycine] applied posttransplant in peppers (Capsicum annuumL.) but preemergence to hairy galinsoga [Galinsoga ciliata(Raf.) Blake # GASCI] controlled the weed at 1.7 to 2.2 kg ai/ha. No serious crop injury or yield reduction was observed when diethatyl was applied to peppers at 9 kg/ha posttransplant or at bloom. Soil ridging, practiced to improve drainage and control the crown rot phase of Phytophthora blight (Phytophthora capsiciL.), limited the duration of weed control by disrupting the herbicide-treated surface soil and exposing untreated soil. Diethatyl applied at 2.2 kg/ha posttransplant and again at pepper bloom, after the soil ridges were formed, controlled hairy galinsoga throughout the entire growing and harvest season.

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Sensitivity of Populations of Phytophthora capsici from South Carolina to Mefenoxam, Dimethomorph, Zoxamide, and Cymoxanil

Plant Disease ◽

10.1094/pdis-91-6-0743 ◽

2007 ◽

Vol 91 (6) ◽

pp. 743-748 ◽

Cited By ~ 50

Author(s):

Anthony P. Keinath

Keyword(s):

South Carolina ◽

Standard Deviation ◽

Mycelial Growth ◽

Phytophthora Capsici ◽

Crown Rot ◽

Phytophthora Blight ◽

Colony Diameter ◽

Zoospore Production ◽

Summer Squash ◽

Cyst Germination

In summer and fall 2003, Phytophthora blight and crown rot, caused by Phytophthora capsici, was found in three fields each of summer squash and pepper on three farms in two counties in South Carolina. Although this disease had been confirmed previously in the state, five of these outbreaks were in fields thought to be free of P. capsici. The objectives of this study were to determine whether isolates of P. capsici in South Carolina were sensitive to mefenoxam and to determine baseline sensitivities to dimethomorph, zoxamide, and cymoxanil, fungicides recently registered to control Phytophthora blight. Of 120 isolates tested for sensitivity to mefenoxam at 100 mg/liter, 8 isolates were resistant (relative colony diameter [RCD] > 90% of nonamended control), 60 isolates were sensitive (RCD < 30%), and 52 isolates were intermediately sensitive. Only sensitive isolates were found in two fields in which no mefenoxam-containing fungicides had ever been used. Intermediately sensitive or resistant isolates were found in the four fields in which mefenoxam had been applied previously. In all, 15 to 61 isolates were tested for sensitivity to dimethomorph, zoxamide, and cymoxanil. The concentrations at which RCD, percent cyst germination, and relative zoospore production were reduced to 50% (EC50 values) for mycelial growth were 0.19 ± 0.02 (± standard deviation) mg/liter for dimethomorph, 0.50 ± 0.50 mg/liter for zoxamide, and mostly >50 mg/liter for cymoxanil. EC50 values for zoospore cyst germination were 0.07 ± 0.02 mg/liter for dimethomorph and >50 mg/liter for cymoxanil. EC50 values for zoospore production were 0.63 ± 0.42 mg/liter for dimethomorph, 0.47 ± 0.51 mg/liter for zoxamide, and <50 mg/liter for cymoxanil. Sensitivity values obtained in this South Carolina study can be used as a comparative baseline to monitor shifts in sensitivity to the fungicides mefenoxam, dimethomorph, zoxamide, and cymoxanil in populations of P. capsici.

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Using Soil-Applied Fungicides to Manage Phytophthora Crown and Root Rot on Summer Squash

Plant Disease ◽

10.1094/pdis-12-11-1071-re ◽

2013 ◽

Vol 97 (1) ◽

pp. 107-112 ◽

Cited By ~ 10

Author(s):

M. D. Meyer ◽

M. K. Hausbeck

Keyword(s):

Root Rot ◽

Yield Loss ◽

Field Trials ◽

Crown Rot ◽

Growth Stages ◽

Post Inoculation ◽

Application Method ◽

Summer Squash ◽

Application Methods ◽

Crown And Root Rot

Phytophthora crown and root rot (Phytophthora capsici) of summer squash is especially difficult to manage because all commercial cultivars are highly susceptible to P. capsici. Producers have traditionally relied on foliar fungicide applications to control Phytophthora crown and root rot despite their limited efficacy. Soil fungicide applications, including via subsurface drip chemigation, have recently gained interest as a method of improving control of P. capsici infections. In this study, soil drenches and foliar applications of 11 fungicides were compared for control of Phytophthora crown and root rot of summer squash in replicated field and greenhouse trials. Fungicides were applied at 7-day intervals. Incidence (%) of plant death was assessed from 7 to 42 days post inoculation (dpi) in field trials. Crown rot severity was rated on a scale of 1 (no wilting) to 5 (plant death) from 5 to 21 dpi in greenhouse trials. Results of field and greenhouse trials were similar. Plant death of ‘Cougar’ following inoculation with P. capsici isolate 12889 occurred at all growth stages from first true-leaf to full maturity in field trials. Plant death 42 dpi differed significantly (P ≤ 0.0001) among fungicides and application methods. The fungicide–application method interaction also was significant. Some fungicides were ineffective regardless of application method. In general, soil drenches were more effective than foliar applications at limiting plant death but no treatment completely controlled disease symptoms. Mean plant death 42 dpi was 41% for soil drenches and 92% for foliar sprays. Drenches of fluopicolide, mandipropamid, or dimethomorph limited plant death to ≤10% and prevented yield loss associated with root and crown rot. Foliar applications generally did not reduce plant death compared with the untreated, inoculated control, and were unable to prevent yield loss in field trials. In greenhouse trials, crown rot severity differed significantly (P ≤ 0.0001) among fungicides, application methods, and cultivars when plants were inoculated with P. capsici isolate 12889 or SP98. Crown rot was less severe and disease progress was slower following soil drenches than foliar applications. Some fungicide treatments were more effective on ‘Leopard,’ which was less susceptible to P. capsici than ‘Cougar.’ Soil application methods, including soil drench and drip chemigation, should be evaluated when fungicides are registered for soilborne disease control, because these methods provide better control of Phytophthora crown and root rot than foliar application.

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Evaluation of Fruit Rot Resistance in Cucurbita Germplasm Resistant to Phytophthora capsici Crown Rot

HortScience ◽

10.21273/hortsci.49.3.285 ◽

2014 ◽

Vol 49 (3) ◽

pp. 285-288 ◽

Cited By ~ 4

Author(s):

Charles S. Krasnow ◽

Rachel P. Naegele ◽

Mary K. Hausbeck

Keyword(s):

Disease Susceptibility ◽

Phytophthora Capsici ◽

Crown Rot ◽

Fruit Rot ◽

Controlled Environment ◽

Post Inoculation ◽

Phytophthora Blight ◽

Lesion Area ◽

Root And Crown Rot ◽

Pericarp Thickness

Phytophthora blight is a destructive disease of cucurbits affecting the fruit, leaves, crown, and/or roots. Ten cucurbit PIs with known partial resistance to Phytophthora capsici root and crown rot were evaluated for resistance to Phytophthora fruit rot. Unwounded fruit from field-grown plants of Cucurbita moschata and C. pepo were inoculated in a controlled environment at 7 to 10 or 21 to 24 days post-pollination (dpp) with virulent P. capsici isolates to examine the effect of fruit age on disease development. Inoculated fruit were rated for lesion area and pathogen mycelial growth 7 days post-inoculation (dpi); fruit length, diameter, and pericarp thickness were also rated. Two C. pepo accessions (PI 169417 and PI 181761) had significant resistance to Phytophthora fruit rot at both 7 to 10 dpp and 21 to 24 dpp. All accessions evaluated displayed reduced disease susceptibility as the fruit aged.

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Sustainable Production of Honeydew and Muskmelon in Western Mexico

HortScience ◽

10.21273/hortsci.33.3.495d ◽

1998 ◽

Vol 33 (3) ◽

pp. 495d-495

Author(s):

J. Farias-Larios ◽

A. Michel-Rosales

Keyword(s):

Large Scale ◽

Management Practices ◽

Glomus Intraradices ◽

Cultural Practices ◽

Bare Soil ◽

Western Mexico ◽

First Results ◽

Legume Cover Crop ◽

Banana Leaves ◽

Research Show

In Western Mexico, melon production depends on high-input systems to maximize yield and product quality. Tillage, plasticulture, fumigation with methyl bromide, and fertigation, are the principal management practices in these systems. However, at present several problems has been found: pests as sweetpotato whitefly (Bemisia tabaci Gennadius), aphids (Myzus and Aphis), leafminer (Liryomiza sativae); diseases as Fusarium, Verticilium, and Pseudoperenospora, and weeds demand high pesticide utilization and labor. There is a growing demand for alternative cultural practices, with an emphasis on reducing off-farm input labor and chemicals. Our research is based on use of organic mulches, such as: rice straw, mature maize leaves, banana leaves, sugarcane bagasse, coconut leaves, and living mulches with annual legume cover crop in melons with crop rotation, such as: Canavalia, Stilozobium, Crotalaria, and Clitoria species. Also, inoculations with mycorrhizal arbuscular fungi for honeydew and cantaloupe melon seedlings production are been assayed in greenhouse conditions for a transplant system. The use of life barriers with sorghum, marigold, and other aromatic native plants in conjunction with a colored yellow systems traps for monitoring pests is being studied as well. While that the pest control is based in commercial formulations of Beauveria bassiana for biological control. The first results of this research show that the Glomus intraradices, G. fasciculatum, G. etunicatum, and G. mosseae reached 38.5%, 33.5%, 27.0%, and 31.0% of root infection levels, respectively. Honeydew melons production with rice and corn straw mulches shows an beneficial effect with 113.30 and 111.20 kg/plot of 10 m2 compared with bare soil with 100.20 kg. The proposed system likely also lowers production cost and is applicable to small- and large-scale melon production.

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Age-related Resistance of Diverse Cucurbit Fruit to Infection by Phytophthora capsici

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.134.2.176 ◽

2009 ◽

Vol 134 (2) ◽

pp. 176-182 ◽

Cited By ~ 24

Author(s):

Kaori Ando ◽

Sue Hammar ◽

Rebecca Grumet

Keyword(s):

Cucumis Melo ◽

Cucurbita Pepo ◽

Citrullus Lanatus ◽

Phytophthora Capsici ◽

Vegetable Production ◽

Age Related ◽

Cucumber Fruit ◽

Summer Squash ◽

Pronounced Reduction ◽

Green Stage

Phytophthora capsici causes severe losses in vegetable production, including many cucurbit crops. Our previous work showed that cucumber (Cucumis sativus) fruit are most susceptible to P. capsici when they are very young and rapidly elongating, but develop resistance as they approach full length at 10 to 12 days postpollination (DPP). In this study, fruit from seven additional cucurbit crops representing four species, melon (Cucumis melo), butternut squash (Cucurbita moschata), watermelon (Citrullus lanatus), and zucchini, yellow summer squash, acorn squash, and pumpkin (Cucurbita pepo), were tested for the effect of fruit development on susceptibility to P. capsici. Field-grown fruit of the different crops varied in overall susceptibility. Zucchini and yellow summer squash were the most susceptible, with the majority of fruit exhibiting water-soaking symptoms within 24 hours postinoculation. Fruit from all of the crops exhibited size-related decrease in susceptibility, but to varying degrees. Cucumber had the most pronounced effect. In infested fields, cucumber fruit were found to be most frequently infected at the blossom end. Comparison of the peduncle and blossom end showed a difference in susceptibility along the length of the fruit for cucumber, butternut squash, and zucchini. Greenhouse-grown, hand-pollinated pumpkin, acorn squash, and butternut squash showed an age-related decrease in susceptibility similar to field-grown fruit. For all of these fruit, a pronounced reduction in susceptibility accompanied the transition from the waxy green to green stage at ≈3 to 8 DPP.

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Expression analysis of defense-related genes in cucumber (Cucumis sativus L.) against Phytophthora melonis

10.1101/2020.05.02.073601 ◽

2020 ◽

Author(s):

Lida Hashemi ◽

Ahmad Reza Golparvar ◽

Mehdi Nasr Esfahani ◽

Maryam Golabadi

Keyword(s):

Gene Expression ◽

Expression Analysis ◽

Gene Expression Analysis ◽

Molecular Mechanisms ◽

Crown Rot ◽

Economic Losses ◽

Post Inoculation ◽

Expression Ratio ◽

Phytophthora Melonis ◽

Maximum Expression

AbstractPhytophthora melonis is the causal agent of damping-off or crown rot, one of the most destructive cucumber diseases that causes severe economic losses in Iran and some other parts of the world. Despite intense research efforts made in the past years, no permanent cure currently exists for this disease. With the aim to understand the molecular mechanisms of defense against P. melonis, root collars and leaves of four cucumber genotypes consisting of resistant Ramezz; moderately resistant Baby and very susceptible Mini 6-23 and Extrem, were monitored for quantitative gene expression analysis of five antifungal and/or anti-oomycete genes (CsWRKY20, CsLecRK6.1, PR3, PR1-1a and LOX1) at three points after inoculation with P. melonis. The gene expression analysis indicated that P. melonis strongly enhanced the expression of these genes after inoculation in both leaves and root collars. Further, not only the transcript levels of these genes were significantly higher in the resistant and moderately resistance genotypes, but also the time point of the highest relative expression ratio for the five genes was different in the four cucumber genotypes. CsWRKY20 and PR3 showed the maximum expression in Ramezz at 48 hours post inoculation (hpi) while CsLecRK6.1, and LOX1 showed the highest expression at 72 hpi. In addition, PR1-1a showed the maximum expression in the Baby at 72 hpi. Root collars responded faster than leaves and some responses were more strongly up-regulated in root collars than in leaves. The genes found to be involved in disease resistance in two different organs of cucumber after pathogen infection. The results suggest that increased expression of these genes led to activation of defense pathways and could be responsible for a reduced P. melonis colonization capacity in Ramezz and Baby. Overall, this work represents a valuable resource for future functional genomics studies to unravel the molecular mechanisms of C. sativus- P. melonis interaction.

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Differential Survival of Generic E. coli and Listeria spp. in Northeastern U.S. Soils Amended with Dairy Manure Compost, Poultry Litter Compost, and Heat-Treated Poultry Pellets and Fate in Raw Edible Radish Crops

Journal of Food Protection ◽

10.4315/jfp-21-261 ◽

2021 ◽

Author(s):

Marie Limoges ◽

Deborah A. Neher ◽

Thomas R. Weicht ◽

Patricia D. Millner ◽

Manan Sharma ◽

...

Keyword(s):

Fresh Produce ◽

Poultry Litter ◽

Dairy Manure ◽

Animal Origin ◽

Most Probable Number ◽

Post Inoculation ◽

Probable Number ◽

E Coli ◽

Manure Compost ◽

Heat Treated

Composted or heat-treated Biological Soil Amendments of Animal Origin (BSAAO) can be added to soils to provide nutrients for fresh produce. These products lower the risk of pathogen contamination of fresh produce when compared with use of untreated BSAAO; however, meteorological conditions, geographic location, and soil properties can influence the presence of pathogenic bacteria, or their indicators (e.g., generic E. coli) and allow potential for produce contamination. Replicated field plots of loamy or sandy soils were tilled and amended with dairy manure compost (DMC), poultry litter compost (PLC), or no compost (NoC) over two different field seasons, and non-composted heat-treated poultry pellets (HTPP) during the second field season. Plots were inoculated with a three-strain cocktail of rifampicin-resistant E. coli (rE.coli) at levels of 8.7 log CFU/m2. Direct plating and most probable number (MPN) methods measured the persistence of rE.coli and Listeria spp. in plots through 104 days post-inoculation. Greater survival of rE. coli was observed in PLC plots in comparison to DMC plots and NoC plots during year 1 (P < 0.05). Similar trends were observed for year 2, where rE. coli survival was also greater in HTPP amended plots (P < 0.05). Survival of rE. coli was dependent on soil type, where water potential and temperature were significant covariables. Listeria spp. were found in NoC plots, but not in plots amended with HTPP, PLC or DMC. Radish data demonstrate that PLC treatment promoted the greatest level of rE.coli translocation when compared to DMC and NoC treatments (P < 0.05). These results are consistent with findings from studies conducted in other regions of the US and informs Northeast produce growers that composted and non-composted poultry-based BSAAO supports greater survival of rE. coli in field soils. This result has the potential to impact the food safety risk of edible produce grown in BSAAO amended soils as a result of pathogen contamination.

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