Detection of Phytophthora capsici from irrigation ponds in South Georgia

2021 ◽  
Author(s):  
Owen Hudson ◽  
Sumyya Waliullah ◽  
Pingsheng Ji ◽  
Justin Hand ◽  
Jake Price ◽  
...  
Keyword(s):  
Phytophthora Capsici ◽  
Disease Outbreaks ◽  
Lamp Assay ◽  
Control Measures ◽  
Vegetable Crops ◽  
Phytophthora Blight ◽  
Filtration Method ◽  
South Georgia ◽  
Detection And Identification ◽  
Wide Range

Phytophthora capsici, the causal agent of Phytophthora blight, is a prominent and economically damaging oomycete pathogen in South Georgia. P. capsici causes crown, root, leaf, stem, and fruit infections on a wide range of vegetable crops. Oomycete pathogens such as P. capsici are dispersed in water as their zoospores are flagellated and can move through runoff. Irrigation ponds are often reservoirs for different pathogens and reusing the captured runoff is increasing in popularity to decrease irrigation costs. This combination allows for unintended outbreaks of diseases by pumping the contaminated runoff onto susceptible crops. Detection and identification of these pathogens is a crucial step in disease management and rapid detection can ensure timely application of disease control measures. In this study, 42 irrigation ponds in nine counties from South Georgia were surveyed for the presence of P. capsici using a novel filtration method in conjunction with a LAMP assay specific for P. capsici. Ten ponds in five counties were found to have P. capsici as detected from the assay, suggesting that testing of irrigation ponds for P. capsici and other pathogens should be conducted to assist in preventing disease outbreaks.

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

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1337-1342 ◽  
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.

scholarly journals Advances in Research on Phytophthora capsici on Vegetable Crops in The United States

Plant Disease ◽  
2012 ◽  
Vol 96 (11) ◽  
pp. 1588-1600 ◽  
Author(s):  
Leah L. Granke ◽  
Lina Quesada-Ocampo ◽  
Kurt Lamour ◽  
Mary K. Hausbeck
Keyword(s):  
Host Range ◽  
Phytophthora Capsici ◽  
The United States ◽  
Fruit Rot ◽  
Economic Losses ◽  
Future Research ◽  
Vegetable Crops ◽  
Long Distance ◽  
Term Survival ◽  
Wide Range

Since L. H. Leonian's first description of Phytophthora capsici as a pathogen of chile pepper in 1922, we have made many advances in our understanding of this pathogen's biology, host range, dissemination, and management. P. capsici causes foliar blighting, damping-off, wilting, and root, stem, and fruit rot of susceptible hosts, and economic losses are experienced annually in vegetable crops including cucurbits and peppers. Symptoms of P. capsici infection may manifest as stunting, girdling, or cankers for some cultivars or crops that are less susceptible. P. capsici continues to be a constraint on production, and implementation of an aggressive integrated management scheme can still result in insufficient control when weather is favorable for disease. Management of diseases caused by P. capsici is currently limited by the long-term survival of the pathogen as oospores in the soil, a wide host range, long-distance movement of the pathogen in surface water used for irrigation, the presence of fungicide-resistant pathogen populations, and a lack of commercially acceptable resistant host varieties. P. capsici can infect a wide range of hosts under laboratory and greenhouse conditions including cultivated crops, ornamentals, and native plants belonging to diverse plant families. As our understanding of P. capsici continues to grow, future research should focus on developing novel and effective solutions to manage this pathogen and prevent economic losses due to the diseases it causes.

scholarly journals Comparison of chili pepper breeding populations for agronomic traits and polygenic resistance to Phytophthora blight

2020 ◽  
Vol 38 (1) ◽  
pp. 12-20
Author(s):  
Bekir Bülent Arpaci ◽  
Kerim Karataş
Keyword(s):  
Agronomic Traits ◽  
Phytophthora Capsici ◽  
Chili Pepper ◽  
Breeding Period ◽  
Phytophthora Blight ◽  
Breeding Populations ◽  
Wide Range ◽  
Stem Necrosis ◽  
Highly Correlated ◽  
Resistance Component

ABSTRACT Belonging to the Oomycete class, Phytophthora capsici has wide range of host profile and is responsible for many devastating diseases in many countries. In addition to time consuming problem for transferring resistance to susceptible varieties, backcrossing method causes losing of genes providing resistance to susceptible varieties. In this study transferring P. capsici resistance genes to susceptible chili pepper lines was aimed during the extensive breeding period and resistant lines were confirmed by marker assistance. Two different breeding populations from CM334 and PM217 were compared by stem inoculation test to determine receptivity, inducibility, and stability resistance component. CM334 was found more effective for transferring all resistance components while PM217 was found suitable for keeping agronomic traits along with two important resistance component inducibility and stability. These two resistant components were found highly correlated to length of stem necrosis. C-29 and C-18 have been improved from CM334 as resistant as CM334; P-73 and P-77 have been improved satisfactorily resistant and yielded lines from PM217. Marker assisted selection proved that resistance of lines differentiated phenotypically despite the genotypes have the same genes.

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

HortScience ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 164-170 ◽  
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.

Fitness and competitive ability of field isolates of Phytophthora capsici resistant or sensitive to fluopicolide

Plant Disease ◽  
2020 ◽  
Author(s):  
Li Wang ◽  
Pingsheng Ji
Keyword(s):  
Mycelial Growth ◽  
Competitive Ability ◽  
Phytophthora Capsici ◽  
Bell Pepper ◽  
Vegetable Production ◽  
Vegetable Crops ◽  
Phytophthora Blight ◽  
Field Isolates ◽  
Significant Difference ◽  
The World

Phytophthora blight, caused by Phytophthora capsici, is one of the most destructive diseases in the production of solanaceous and cucurbitaceous vegetable crops. Fluopicolide has been used to control the disease; however, reduced efficacy of the fungicide was observed in Georgia. P. capsici isolates were collected from commercial vegetable fields in Georgia in 2018 and 2019 to determine sensitivity to fluopicolide, which were phenotyped to have 43.1% of the isolates as resistant. The fitness of resistant (R) and sensitive (S) isolates was assessed through mycelial growth and sporulation assays exposed to the fungicide (0 or 50 µg/ml). Fluopicolide did not reduce mycelial growth, sporangial production and zoospore germination of the resistant isolates. In the absence of fluopicolide, there was no significant difference between the R and S isolates in sporangial production, but mycelial growth and zoospore germination of the R isolates was greater than the S isolates (P = 0.01 and 0.001, respectively). The R isolates had similar ability as S isolates to induce disease on ‘Aristotle’ bell pepper, and most of the R and S isolates caused the same level of disease on ‘Paladin’. Inoculating squash fruit using different R:S ratios and recovering R and S isolates after 5 cycles of inoculation resulted in similar trends in changes of R vs. S isolates ratios. Overall it appeared that fitness and competitive ability of the R isolates were not reduced compared to the S isolates. This is the first report of the occurrence of field isolates of P. capsici resistant to fluopicolide in the world. The results have significant implications in providing guidance for growers to avoid or limit use of this fungicide in vegetable production.

A Diagnostic Guide for Phytophthora capsici infecting vegetable crops

2021 ◽  
Author(s):  
Camilo H. Parada-Rojas ◽  
Leah Granke ◽  
Rachel Naegele ◽  
Zachariah Hansen ◽  
Mary Hausbeck ◽  
...  
Keyword(s):  
Molecular Identification ◽  
Phytophthora Capsici ◽  
Vegetable Crops ◽  
Disease Symptoms ◽  
Plant Parts ◽  
Long Term Storage ◽  
Wide Range ◽  
Oomycete Pathogen ◽  
Term Storage

Phytophthora capsici is an oomycete pathogen causing economically important diseases in a wide range of hosts worldwide including cucurbitaceous, solanaceous, and fabaceous crops. All plant parts, crown and roots, or only the fruit may be affected depending on the host, and symptoms can range from wilting to rot and plant death. Considered a hemibiotroph, P. capsici can be cultured in artificial media and maintained in long term storage. In this diagnostic guide, we describe methods to identify P. capsici infection based on disease symptoms and pathogen signs. We also outline methods for molecular identification, pathogen isolation, storage of single-sporangium cultures, and pathogenicity testing.

A field evaluation of jalapeño and non-jalapeño chile pepper resistance to Phytophthora blight caused by Phytophthora capsici

2021 ◽  
Author(s):  
Srijana Dura ◽  
Phillip A Lujan ◽  
Ivette Guzman ◽  
Robert Steiner ◽  
Soum Sanogo
Keyword(s):  
Disease Incidence ◽  
Phytophthora Capsici ◽  
Field Evaluation ◽  
Severity Index ◽  
Vegetable Crops ◽  
Phytophthora Blight ◽  
Inoculum Level ◽  
Chile Pepper ◽  
Progress Curve ◽  
Stage Disease

Phytophthora capsici is a destructive soilborne pathogen, which causes Phytophthora blight in many vegetable crops including chile pepper (Capsicum sp.). Our research was aimed at evaluating the resistance of jalapeño cultivars in field conditions and identifying the factors associated with reduction of Phytophthora blight caused by P. capsici. Six jalapeño (NuMex Orange Spice, NuMex Pumpkin Spice, NuMex Jalmundo, TAM Jalapeño, Early Jalapeño, and NuMex Vaquero) and two non-jalapeño (CM-334 and NM 6-4) cultivars were inoculated with P. capsici at the fruiting stage. Disease severity index (DSI), disease incidence (DI), and area under the disease progress curve (AUDPC) for each cultivar were measured. The most susceptible jalapeño cultivars with the highest DSI, DI, and AUDPC were NuMex Orange Spice, NuMex Jalmundo and NuMex Pumpkin Spice, whereas the least susceptible jalapeño cultivars were Early Jalapeño, TAM Jalapeño, and NuMex Vaquero, with the lowest DSI, DI, and AUDPC. The identified jalapeños with reduced susceptibility to Phytophthora blight can be planted in infested fields, combined with other control methods which may help in soil disinfestation by reducing the inoculum level in soil over time.

scholarly journals Applying Drone-based Spatial Mapping to Help Growers Manage Crop Diseases

2021 ◽  
Author(s):  
Qingren Wang ◽  
Shouan Zhang
Keyword(s):  
Disease Incidence ◽  
Phytophthora Capsici ◽  
Cost Effective ◽  
Labor Cost ◽  
Spatial Mapping ◽  
Vegetable Crops ◽  
Yield Losses ◽  
Phytophthora Blight ◽  
Rapid Spread ◽  
Wet Weather

Phytophthora blight (Phytophthora capsici) is one of the major soilborne diseases threatening many vegetable crops including squash. The disease results in severe epidemics and yield losses due to a rapid spread of the pathogen associated with wet weather and soil waterlogging. Implementing drone-based spatial mapping with software elevation tools can assist growers in evaluating land levelling for uniform distribution of water to mitigate potential disease incidence. The technology has great advantages: rapid, precise, and labor-cost effective. Our result can implicate Extension professionals with application of spatial mapping to assist growers in managing their land and crops for disease control efficiently.

COVID-19 Outbreak Prediction with Machine Learning

2020 ◽  
Author(s):  
Sina Faizollahzadeh Ardabili ◽  
Amir Mosavi ◽  
Pedram Ghamisi ◽  
Filip Ferdinand ◽  
Annamaria R. Varkonyi-Koczy ◽  
...  
Keyword(s):  
Machine Learning ◽  
Prediction Models ◽  
Fuzzy Inference ◽  
Control Measures ◽  
Future Research ◽  
Complex Nature ◽  
Inference System ◽  
Wide Range ◽  
Standard Models ◽  
High Level

Several outbreak prediction models for COVID-19 are being used by officials around the world to make informed-decisions and enforce relevant control measures. Among the standard models for COVID-19 global pandemic prediction, simple epidemiological and statistical models have received more attention by authorities, and they are popular in the media. Due to a high level of uncertainty and lack of essential data, standard models have shown low accuracy for long-term prediction. Although the literature includes several attempts to address this issue, the essential generalization and robustness abilities of existing models needs to be improved. This paper presents a comparative analysis of machine learning and soft computing models to predict the COVID-19 outbreak as an alternative to SIR and SEIR models. Among a wide range of machine learning models investigated, two models showed promising results (i.e., multi-layered perceptron, MLP, and adaptive network-based fuzzy inference system, ANFIS). Based on the results reported here, and due to the highly complex nature of the COVID-19 outbreak and variation in its behavior from nation-to-nation, this study suggests machine learning as an effective tool to model the outbreak. This paper provides an initial benchmarking to demonstrate the potential of machine learning for future research. Paper further suggests that real novelty in outbreak prediction can be realized through integrating machine learning and SEIR models.

An Improved Membrane Filtration Method for Enumeration of Faecal Coliforms and E. Coli by a Fluorogenic β-Glucuronidase Assay

1993 ◽  
Vol 27 (3-4) ◽  
pp. 267-270 ◽  
Author(s):  
M. T. Augoustinos ◽  
N. A. Grabow ◽  
B. Genthe ◽  
R. Kfir
Keyword(s):  
Escherichia Coli ◽  
Water Samples ◽  
Membrane Filtration ◽  
Faecal Coliforms ◽  
Environmental Waters ◽  
Filtration Method ◽  
E Coli ◽  
Wide Range ◽  
Pure Cultures ◽  
Glucuronidase Assay

A fluorogenic β-glucuronidase assay comprising membrane filtration followed by selective enumeration on m-FC agar at 44.5°C and further confirmation using tlie 4-metliylumbelliferyl-β-D-glucuronide (MUG) containing medium was evaluated for the detection of Escherichia coli in water. A total of 200 typical blue and non-typical blue colonies were isolated from sea and fresh water samples using initial selective enumeration on m-FC agar. Pure cultures of the selected colonies were further tested using the MUG assay and identified using the API 20E method. Of the colonies tested which were shown to be positive using the MUG assay 99.4% were Escherichia coli. The results of this study indicate the combination of the m-FC method followed by the MUG assay to be highly efficient for the selection and confirmation of E. coli from a wide range of environmental waters.

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