Evaluation of Biorational Products for Management of Phytophthora Blight of Bell Pepper Transplants

There is a critical need for pest control products that are compatible with sustainable agricultural practices, such as those based on natural antagonists or plant defense activators. Four separate, repeated experiments were conducted in which commercially available biopesticides and phosphonate-containing products were evaluated in the greenhouse for the management of Phytophthora blight of bell pepper caused by Phytophthora capsici. The phosphonate-containing product, FNX-100, applied as a soil drench, was found to be the most effective treatment for decreasing the incidence of stem and crown rot. A single soil drench of FNX-100 applied at the lowest concentration provided disease control that was as effective as multiple applications of the highest rate. Foliar applications of FNX-100 at any concentration or frequency were ineffective for disease control, and caused pronounced phytotoxicity when compared to the FNX-100 soil drench. The phosphorous acid K-Phite was found to be less effective than FNX-100, but disease symptoms were minimal in plants treated with a soil drench of that product. While the efficacy of three other phosphonate-containing products, Prophyt, Phostrol, and FNX-2500, were inconsistent, it was observed that these products were also more effective in managing disease when applied as a soil drench rather than as a foliar spray. Accepted for publication 18 December 2012. Published 26 February 2013.

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Evaluation of Commercial Bell Pepper Cultivars for Resistance to Phytophthora Blight (Phytophthora capsici)

Plant Health Progress ◽

10.1094/php-rs-13-0114 ◽

2014 ◽

Vol 15 (1) ◽

pp. 19-24 ◽

Cited By ~ 6

Author(s):

Amara R. Dunn ◽

Holly W. Lange ◽

Christine D. Smart

Keyword(s):

New York ◽

Phytophthora Capsici ◽

New York State ◽

Field Trials ◽

Bell Pepper ◽

Crown Rot ◽

Fruit Rot ◽

Phytophthora Blight ◽

The North ◽

Bell Peppers

Phytophthora blight (Phytophthora capsici) is an important disease of bell peppers, causing crown, root, and fruit rot as well as foliar lesions. Substantial yield losses can result from either plant death or fruit rot. Host resistance is an effective management strategy for the root and crown rot phase of the disease, and a number of commercially-available pepper cultivars are described by the supplier as intermediately resistant. In field trials conducted over 5 years, the bell pepper cultivars Archimedes, Aristotle, Intruder, and Paladin were found to be the most resistant to a single isolate of P. capsici from New York State (NY 0664-1). Cultivars ACR285, Declaration, PS 09941819, Revolution, and Vanguard showed intermediate levels of resistance. Escalade, Karisma, Keystone Giant, King of the North, and Red Knight were highly susceptible to NY 0664-1. This information will be useful to growers selecting cultivars to plant in fields with a history of Phytophthora blight. Accepted for publication 24 October 2013. Published 30 January 2014.

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Sensitivity of Phytophthora capsici on Vegetable Crops in Georgia to Mandipropamid, Dimethomorph, and Cyazofamid

Plant Disease ◽

10.1094/pdis-12-11-1082-re ◽

2012 ◽

Vol 96 (9) ◽

pp. 1337-1342 ◽

Cited By ~ 25

Author(s):

K. L. Jackson ◽

J. Yin ◽

P. Ji

Keyword(s):

Disease Management ◽

Mycelial Growth ◽

Phytophthora Capsici ◽

Chemical Compounds ◽

Bell Pepper ◽

Vegetable Production ◽

Vegetable Crops ◽

Phytophthora Blight ◽

Significant Component ◽

Serious Disease

Phytophthora blight, caused by Phytophthora capsici, is a serious disease in vegetable production, and selective use of fungicides continues to be a significant component of disease management programs. The effect of three chemical compounds—mandipropamid, dimethomorph, and cyazofamid—on asexual stages of P. capsici collected from bell pepper and cucurbits in Georgia was assessed in this study. Forty isolates of P. capsici were determined to be sensitive to mandipropamid and dimethomorph based on mycelial growth, zoospore germination, and sporangial production. Concentrations that were 50% effective (EC50 values) of mandipropamid that inhibited mycelial growth, zoospore germination, and sporangial production of the isolates averaged 0.03, 5.70, and 0.02 μg/ml, respectively. EC50 values of dimethomorph in inhibiting mycelial growth, zoospore germination, and sporangial production averaged 0.24, 0.10, and 0.46 μg/ml, respectively. The majority of isolates were either resistant or intermediately sensitive to cyazofamid at 500 μg/ml or lower concentrations based on mycelial growth or sporangial production, although all the isolates were sensitive to this compound based on zoospore germination, with an average EC50 of 0.04 μg/ml. The results indicated that P. capsici populations in Georgia have not developed resistance to mandipropamid and dimethomorph whereas, for the majority of the isolates, certain asexual stages were resistant to cyazofamid.

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Management of Phytophthora Crown Rot in Pumpkin and Zucchini Seedlings with Phosphonates

Plant Disease ◽

10.1094/pdis-91-12-1651 ◽

2007 ◽

Vol 91 (12) ◽

pp. 1651-1656 ◽

Cited By ~ 6

Author(s):

Camilla B. Yandoc-Ables ◽

Erin N. Rosskopf ◽

Elizabeth M. Lamb

Keyword(s):

Management Strategies ◽

Foliar Spray ◽

Crown Rot ◽

Application Method ◽

Soil Drench ◽

Cultivar Selection ◽

Treatment Type ◽

Copper Manganese ◽

Foliar Fungicide ◽

Affect Disease Severity

Experiments were conducted in the greenhouse to determine the efficacy of two phosphonate-containing fungicides (FNX-100 and FNX-2500) against Phytophthora crown rot of pumpkin. The experiments were designed to determine the effects of crop cultivar, application method (soil drench versus foliar spray), and phosphonate concentration on the level of effectiveness of a crown rot management strategy using phosphonates. Pumpkin cultivar, treatment (type of fungicide product), phosphonate concentration, and application method significantly influenced the level of Phytophthora crown rot control. Between the two fungicides, only FNX-100 suppressed Phytophthora crown rot in pumpkin. For cv. Phantom, the highest level of control was achieved with the drench application of 3.0% FNX-100 whereas, for cv. Spooktacular, all three concentrations of FNX-100 (1.0, 2.0, and 3.0%, vol/vol) applied as a soil drench suppressed or significantly reduced the severity of crown rot. Additional experiments using zucchini as test plants demonstrated that, at the concentrations tested, FNX-100 was more efficacious than FNX-2500 in controlling Phytophthora crown rot and that zucchini cultivar or FNX-100 concentration did not significantly influence crown rot control with phosphonates. In this study, FNX-100, which is not currently labeled for use in vegetables, provided satisfactory disease control in both pumpkin and zucchini whereas FNX-2500, a foliar fungicide comprised of the phosphate/phosphonates and copper, manganese, and zinc, did not significantly affect disease severity. This study, albeit limited in scope, showed that cultivar selection may play an important role in the successful management of Phytophthora crown rot on cucurbits with phosphonates, information which may be useful in designing additional tests and developing management strategies for pumpkin and zucchini that are grown in the field.

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Performance and Tolerance to Phytophthora Blight of Bell Pepper Varieties

HortTechnology ◽

10.21273/horttech.23.3.382 ◽

2013 ◽

Vol 23 (3) ◽

pp. 382-390 ◽

Cited By ~ 5

Author(s):

Amara R. Dunn ◽

Lindsay E. Wyatt ◽

Michael Mazourek ◽

Stephen Reiners ◽

Christine D. Smart

Keyword(s):

New York ◽

Phytophthora Capsici ◽

Fruit Size ◽

Bell Pepper ◽

Plant Structure ◽

Phytophthora Blight ◽

Marketable Yield ◽

Breeding Lines ◽

History Of ◽

Low Incidence

In 2011, total marketable yield, fruit size, and number of lobes; fruit discoloration due to silvering; and plant structure were compared among eight commercial green bell pepper (Capsicum annuum) varieties and four breeding lines at three field sites in central New York. Tolerance to phytophthora blight (Phytophthora capsici) was also assessed at one of these sites. No wilting or plant death due to phytophthora blight was observed on the four breeding lines. ‘Paladin’, ‘Intruder’, and ‘Aristotle’ had the highest levels of tolerance to phytophthora blight, among the commercial varieties and maintained their yields in the presence of disease. In the absence of phytophthora blight, yields from these three varieties were comparable to susceptible varieties, but fruit tended to be smaller, and incidence of silvering was high in ‘Paladin’ and ‘Intruder’. Less silvering was observed on ‘Aristotle’ fruit. Total marketable yields from the breeding lines and percent of fruit with four lobes was comparable to the commercial varieties, and some breeding lines also had a low incidence of silvering, but fruit were smaller and set later in the season. Overall, this study suggests that ‘Paladin’, ‘Intruder’, and ‘Aristotle’ will yield well in fields with a history of severe phytophthora blight, but new large-fruited varieties with low incidence of silvering and good tolerance to phytophthora blight are needed.

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Insensitivity to Ridomil Gold (Mefenoxam) Found Among Field Isolates of Phytophthora capsici Causing Phytophthora Blight on Bell Pepper in North Carolina and New Jersey

Plant Disease ◽

10.1094/pdis.1998.82.6.711d ◽

1998 ◽

Vol 82 (6) ◽

pp. 711-711 ◽

Cited By ~ 34

Author(s):

Greg Parra ◽

Jean Ristaino

Keyword(s):

North Carolina ◽

New Jersey ◽

Cultural Practices ◽

Phytophthora Capsici ◽

Significant Proportion ◽

Bell Pepper ◽

Economic Losses ◽

Mating Types ◽

Phytophthora Blight ◽

Field Isolates

Phytophthora blight caused by the pathogen Phytophthora capsici has caused economic losses in bell pepper and cucurbit fields in the U.S., and the prevalence of the disease has increased in recent years. The pathogen can be dispersed in soil, with surface water, and via splash dispersal from the soil to foliage. Management of the disease relies on modifications in cultural practices, crop rotation, and judicious use of fungicides. Disease occurred in fields that were sprayed with multiple applications of Ridomil Gold (mefenoxam) according to labeled recommendations in 1997. Mefenoxam is the active enantiomer contained in the racemic fungicide metalaxyl. Mefenoxam was widely used on bell pepper for the first time in 1997, but disease was widespread. Insensitivity to mefenoxam and metalaxyl has not been reported previously in field isolates of P. capsici. However, selection for metalaxyl insensitive isolates in the laboratory after mutagenesis has been reported. Insensitivity to metalaxyl has been reported among other Oomycete pathogens including Phytophthora infestans, Pseudoperonospora cubensis, Peronospora tabacina, Bremia lactucae, and Pythium spp. Infected plants were collected from 12 fields in North Carolina by the authors and one additional field in New Jersey (courtesy of Steve Johnston). Infected plants (10 to 30 per field) were surface disinfested in 10% bleach and plated on selective media to isolate P. capsici. Colonies of the pathogen were transferred to V8 juice agar or maintained on cornmeal agar slants. Mefenoxam-amended V8 juice agar was prepared at levels of 0, 5, and 100 ppm. Screening for sensitivity was conducted by placing agar plugs containing the pathogen onto two replicate plates of mefenoxam-amended media at each concentration. Isolates were categorized as sensitive if growth was less than 40% of the unamended control at 5 ppm. Intermediate isolates exhibited growth greater than 40% of the unamended control at 5 ppm but less than 40% of the unamended control at 100 ppm mefenoxam. Insensitive isolates exhibited growth greater than 40% of the unamended control at 100 ppm mefenoxam. Concentrations of the fungicide used to screen for insensitivity were within the range applied in the field. Thus far, 161 isolates have been screened for sensitivity. Of these, 54 isolates were classified as sensitive, 15 as intermediate, and 92 or 57% of the isolates were insensitive. Three quarters of the fields sampled contained insensitive isolates and insensitivity ranged from 11 to 80% within fields. Both A1 and A2 mating types were recovered from some fields and insensitive isolates occurred among both mating types. Isolates that were insensitive to mefenoxam were also insensitive to metalaxyl. A significant proportion of the isolates obtained from infected plants in fields where Ridomil Gold has been used recently were insensitive. The ability of insensitive isolates to cause disease on fungicide-treated plants will be studied in further experiments. Isolates collected between 1988 and 1994 were screened and all isolates were sensitive to metalaxyl (Ridomil 2E). A dramatic shift in populations of P. capsici to insensitivity to the new metalaxyl substitute mefenoxam has occurred in bell pepper fields in a 3-year period.

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Bell Pepper (Capsicum annum L.) Crop as Affected by Shade Level: Fruit Yield, Quality, and Postharvest Attributes, and Incidence of Phytophthora Blight (caused by Phytophthora capsici Leon.)

HortScience ◽

10.21273/hortsci.49.7.891 ◽

2014 ◽

Vol 49 (7) ◽

pp. 891-900 ◽

Cited By ~ 17

Author(s):

Juan Carlos Díaz-Pérez

Keyword(s):

Phytophthora Capsici ◽

Net Photosynthesis ◽

Fruit Yield ◽

Bell Pepper ◽

Soluble Solids ◽

Growth And Yield ◽

Phytophthora Blight ◽

Ir Radiation ◽

Capsicum Annum ◽

Yield Quality

High temperatures can be detrimental to bell pepper, resulting in reduced fruit yield and increased incidences of fruit disorders such as sunscald and blossom-end rot. Shade nets are used to modify the crop microenvironment to improve plant growth and yield. The objectives were to evaluate effects of shade level on fruit yield, quality, and postharvest attributes and the incidence of Phytophthora blight (caused by Phytophthora capsici Leon.) in bell pepper (Capsicum annum L.). Experiments were conducted in Tifton, GA, in 2008 (with cv. Heritage) and 2009 and 2010 (with cvs. Camelot, Lafayette, Sirius, and Stiletto). Bell pepper plants were grown under shade levels of 0% (unshaded, as a control), 30%, 47%, 63%, and 80%. Shade level affected fruit yield, quality, postharvest attributes, and incidence of Phytophthora blight in plants. Total marketable (Fancy and US1) fruit yield increased with increasing shade level to a maximum at 35% shade and then decreased with further increments in shade level. Relative to unshaded plants, marketable yields were improved by 119% (2008) and 43% (2009 and 2010) at 35% shade level. US2 and cull (sunscald) fruit number declined with increasing shade level. ‘Camelot’ produced among the greatest number and yield of marketable fruit; ‘Sirius’ had the heaviest fruit and greatest number of culls. Fruit nitrogen (N), phosphorus (P), and potassium (K) concentrations increased and aluminum (Al), molybdenum (Mo), and nickel (Ni) decreased with increasing shade level. ‘Lafayette’ had the highest fruit concentration of N, calcium (Ca), sulfur (S), manganese (Mn), and zinc (Zn). Fruit soluble solids and percent of fruit dry weight decreased with increasing shade level; fruit water loss rate and bacterial soft rot incidence were unaffected. Fruit skin a* and b* values decreased in yellow fruit cultivars (‘Lafayette’ and ‘Sirius’) with increased shade level. Incidences of Phytophthora blight in plants and fruit sunscald decreased with shade level. Beneficial effects of shading on bell pepper were associated with a reduction in irradiation, air temperature, and soil temperature under shaded conditions resulting in amelioration of heat stress in the plants. Optimal shade level for maximal fruit yield was that which maximized the cooling effect resulting from reduction of infrared (IR) radiation and minimized the decrease in net photosynthesis resulting from reduction in photosynthetically active radiation (PAR).

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Screening Capsicum annuum Accessions for Resistance to Six Isolates of Phytophthora capsici

HortScience ◽

10.21273/hortsci.45.2.254 ◽

2010 ◽

Vol 45 (2) ◽

pp. 254-259 ◽

Cited By ~ 16

Author(s):

Byron L. Candole ◽

Patrick J. Conner ◽

Pingsheng Ji

Keyword(s):

Capsicum Annuum ◽

Root Rot ◽

Phytophthora Capsici ◽

Bell Pepper ◽

Initial Screening ◽

Phytophthora Blight ◽

Sources Of Resistance ◽

Potential Sources ◽

Bell Peppers ◽

Seed Increase

Phytophthora blight caused by Phytophthora capsici Leon. is one of the most important diseases of bell peppers (Capsicum annuum L.) in Georgia. The level of resistance in commercial bell pepper cultivars is not effective in managing this disease in moist and humid conditions, and new sources of resistance are needed. A mixture of six Georgia isolates of P. capsici was used for greenhouse mass screening of 2301 accessions of Capsicum annuum. From the initial screening, 77 accessions were identified as resistant to P. capsici-induced root rot. From those 77 accessions, 28 accessions were selected for seed increase and further replicated root inoculation tests. Replicated tests confirmed the resistance of 14 of the 28 accessions, although genetic variability within the accessions hampered the analysis of resistance in some accessions. Two accessions, PI 201237 and PI 640532, demonstrated consistently high levels of resistance to root rot. These two accessions are potential sources of resistance genes that can be incorporated into commercial bell pepper cultivars.

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First Report of Phytophthora capsici Causing Wilting and Root and Crown Rot on Capsicum annuum (Bell Pepper) in Ecuador

Plant Disease ◽

10.1094/pdis-11-19-2432-pdn ◽

2020 ◽

Vol 104 (7) ◽

pp. 2032-2032 ◽

Cited By ~ 1

Author(s):

Jefferson Bertin Vélez-Olmedo ◽

Luis Saltos ◽

Liliana Corozo ◽

Bianca Samay Bonfim ◽

Sergio Vélez-Zambrano ◽

...

Keyword(s):

Capsicum Annuum ◽

Phytophthora Capsici ◽

Bell Pepper ◽

Crown Rot ◽

First Report ◽

Root And Crown Rot

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First Report of Phytophthora capsici Infection on Bell Peppers (Capsicum annuum L.) from Punjab, Pakistan

International Journal of Phytopathology ◽

10.33687/phytopath.007.01.2543 ◽

2018 ◽

Vol 7 (1) ◽

pp. 51-51

Author(s):

Sajjad Hyder ◽

Muhammad Inam-ul-Haq ◽

Raees Ahmed ◽

Amjad S. Gondal ◽

Nida Fatima ◽

...

Keyword(s):

Capsicum Annuum ◽

Irrigation System ◽

Phytophthora Capsici ◽

Bell Pepper ◽

Fluorescent Light ◽

Phytophthora Blight ◽

Seedling Mortality ◽

Canal Irrigation ◽

First Report ◽

Capsicum Annuum L

Bell pepper (Capsicum annuum L.) is one of the extensively cultivated vegetable crop in Punjab, Pakistan. During two years of field surveys, February-November 2016-17, damping off and blight symptoms were observed. Average seedling mortality was recorded as 18.7% while yield loss due to blight was estimated 32 to 41% at mature stages. Maximum blight infection was recorded from the areas frequently flooded with canal irrigation system. At early stages, lesions were noticed on stem portions at soil line level while at crop maturity stages blight symptoms were noted. Leaves were blanched and wilted while fruits were covered with white mold. Masses of sporangia were evident on and inside the infected fruits under humid conditions. A total of twelve isolates were recovered from infected root, stem and fruit portions on rye agar media (Caten and Jinks, 1968) incubated at 25oC under fluorescent light. Papillated sporangia were averaged 42 ± 2.6 X 27 ± 1.7 μm in size (range 27 - 52 × 23 - 36 μm). Oospores were produced on 20% V8 agar and were spherical 22 ± 1.4 μm in diameter (range 14 to 27 μm) while average pedicels length was recorded as 58 ± 12.5 μm (range 13 to 120 μm). These observations were similar to those described for P. capsici (Cocoa, 1988). DNA was extracted using Cetyl Trimethylammonium Bromide (CTAB) method and the internal transcribed spacer regions (ITS1 and ITS2) were amplified by polymerase chain reaction (White et al., 1990). The amplicons were purified and sequenced in both directions (GenBank Accession No. MF322868 and MF322869). BLAST analysis revealed these isolates showed 99% identity with ITS sequences of Phytophthora capsici (KM369964 and KU518782). Pathogenicity assay was performed on healthy bell pepper seedlings with five repeats. Soil was flooded with 20ml sporangial suspension (1 x 103 sporangia/ml) in pots containing seedlings while 5ml suspension was sprayed until run off on mature plants (Hyder et al., 2018). A set of uninoculated seedlings was used as control. Pots were kept in dew chamber for 10-20 days at 25±2 oC. Seedling mortality was observed five days after inoculation while at later stage plants develop brown-to-black stem lesions with white mycelial growth on leaves. These symptoms were identical to the P. capsici infections in field. Consistent re-isolations of P. capsici confirm its association with the disease. To our knowledge, this is the first report of Phytophthora blight on bell pepper from Pakistan

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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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