Investigating Chemical and Biological Control Applications for Pythium Root Rot Prevention and Impacts on Creeping Bentgrass Putting Green Rhizosphere Bacterial Communities

Plant Disease ◽  
2021 ◽  
Author(s):  
Joseph Doherty ◽  
Joseph Roberts
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Bacterial Communities ◽  
Environmental Changes ◽  
Creeping Bentgrass ◽  
Amplicon Sequencing ◽  
Disease Suppression ◽  
Pythium Root Rot ◽  
Putting Green ◽  
Rhizosphere Bacterial Communities

Pythium root rot (PRR) is a disease that can rapidly devastate large swaths of golf course putting greens, with little recourse once symptoms appear. Golf courses routinely apply preventative fungicides for root diseases, which may be altering the rhizosphere microbiome leading to unintended impacts to plant health. A multi-year field trial was initiated on a ‘T-1’ creeping bentgrass (Agrostis stolonifera L. cv. ‘T-1’) putting green in College Park, Maryland to evaluate preventative PRR management for disease suppression and impacts to rhizosphere bacterial communities. Fungicides commonly used to prevent PRR and a biological fungicide were repeatedly applied to experimental plots throughout the growing season. Rhizosphere samples were collected twice annually from each plot to evaluate rhizosphere bacterial communities through amplicon sequencing and monitor biological control organism populations via qPCR. Cyazofamid was the only treatment to suppress PRR in both years compared to the control. Fosetyl-Al on a 14 d interval and Bacillus subtilis QST713 also reduced PRR severity in 2019 compared to the non-treated control. Treatments did not significantly alter bacterial communities, however seasonal environmental changes did. Repeated rhizosphere targeted applications of B. subtilis QST713 appear to have established the bacterium into the rhizosphere, as populations increased between samples, even after applications stopped. These findings suggest that QST713 may reduce pathogen pressure when repeatedly applied and can reduce fungicide usage during periods of low PRR pressure.

Biological control of pythium root rot of chrysanthemum in small-scale hydroponic units

2007 ◽  
Vol 35 (2) ◽  
pp. 159-178 ◽  
Author(s):  
W. Liu ◽  
J. C. Sutton ◽  
B. Grodzinski ◽  
J. W. Kloepper ◽  
M. S. Reddy
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Small Scale ◽  
Pythium Root Rot

scholarly journals Preventive Control of Pythium Root Dysfunction in Creeping Bentgrass Putting Greens and Sensitivity of Pythium volutum to Fungicides

Plant Disease ◽  
2009 ◽  
Vol 93 (12) ◽  
pp. 1275-1280 ◽  
Author(s):  
J. P. Kerns ◽  
M. D. Soika ◽  
L. P. Tredway
Keyword(s):  
Fungicidal Activity ◽  
Creeping Bentgrass ◽  
Disease Suppression ◽  
Preventive Control ◽  
Putting Greens ◽  
In Vitro Sensitivity ◽  
Putting Green ◽  
Field Efficacy

Pythium root dysfunction (PRD), caused by Pythium volutum, has been observed on golf course putting greens established with creeping bentgrass in the southeastern United States since 2002. To evaluate preventative strategies for management of this disease, a 3-year field experiment was conducted in Pinehurst, NC on a ‘G-2’ creeping bentgrass putting green. Fungicide treatments were applied twice in the fall (September and October) and three times in the spring (March, April, and May) in each of the 3 years. Applications of pyraclostrobin provided superior preventative control compared with the other fungicides tested. Azoxystrobin and cyazofamid provided moderate control of PRD in two of three seasons. Experiments were conducted to determine whether the disease suppression provided by pyraclostrobin was due to fungicidal activity or physiological effects on the host. In vitro sensitivity to pyraclostrobin, azoxystrobin, fluoxastrobin, cyazofamid, mefenoxam, propamocarb, and fluopicolide was determined for 11 P. volutum isolates and 1 P. aphanidermatum isolate. Isolates of P. volutum were most sensitive to pyraclostrobin (50% effective concentration [EC50] value = 0.005), cyazofamid (EC50 = 0.004), and fluoxastrobin (EC50= 0.010), followed by azoxystrobin (EC50 = 0.052), and mefenoxam (EC50 = 0.139). P. volutum isolates were not sensitive to fluopicolide or propamocarb. Applications of pyraclostrobin did not increase the foliar growth rate or visual quality of creeping bentgrass in growth-chamber experiments. This work demonstrates that fall and spring applications of pyraclostrobin, azoxystrobin, and cyazofamid suppress the expression of PRD symptoms during summer and that field efficacy is related to the sensitivity of P. volutum to these fungicides.

scholarly journals Curative Evaluation of Biological Control Agents and Synthetic Fungicides for Clarireedia jacksonii

HortScience ◽  
2020 ◽  
Vol 55 (10) ◽  
pp. 1622-1625
Author(s):  
Jeffery W. Marvin ◽  
Robert Andrew Kerr ◽  
Lambert B. McCarty ◽  
William Bridges ◽  
S. Bruce Martin ◽  
...  
Keyword(s):  
Biological Control ◽  
Disease Severity ◽  
Warm Season ◽  
Creeping Bentgrass ◽  
Field Studies ◽  
Biological Control Agents ◽  
Dollar Spot ◽  
Clemson University ◽  
Wide Range ◽  
Putting Green

Clarireedia jacksonii sp. nov. formerly Sclerotinia homoeocarpa F.T. Bennett, one of the causal agents of dollar spot, is the most widespread pathogen in turfgrass systems. Dollar spot (DS) affects both cool- and warm-season grasses, during a wide range of environmental conditions. Field studies were conducted at Clemson University, Clemson, SC, on a creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds) cv. Crenshaw] putting green for 2 consecutive years from August to October in year 1 and July to September in year 2. The objective of the studies was to evaluate biological control agents (BCAs) and synthetic fungicides at reduced rates for their efficacy controlling dollar spot. Four replications of 1.5 × 1.5-m plots were used in the experimental design. Treatments included the following: Bacillus subtilis (BS); plant extract oils (EO) including clove oil + wintergreen oil + thyme oil; extract of Reynoutria sachalinensis (RS); Bacillus licheniformis (BL); chlorothalonil (CL); and azoxystrobin + propiconazole (AzP). Synthetic fungicides were used at reduced rates in combination with biological control agents, to evaluate curative control efficacy of various combinations. All reduced synthetic programs, except CL + EO, provided acceptable disease severity (≤15%) at the end of year 1 and acceptable (≥7) turfgrass visual quality. Azoxystrobin + propiconazole, CL, AzP + BL, AzP + EO, AzP + BS all provided ≤15% disease severity and ≥7 visual turfgrass quality 14 days after the last application in year 2.

scholarly journals Integrated Metabarcoding and Culturomic-Based Microbiome Profiling of Rice Phyllosphere Reveal Diverse and Functional Bacterial Communities for Blast Disease Suppression

2021 ◽  
Vol 12 ◽  
Author(s):  
Kuleshwar Prasad Sahu ◽  
Asharani Patel ◽  
Mukesh Kumar ◽  
Neelam Sheoran ◽  
Sahil Mehta ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Rice Blast ◽  
Bacterial Species ◽  
Amplicon Sequencing ◽  
Rice Cultivar ◽  
Disease Suppression ◽  
Blast Disease ◽  
Rrna Gene ◽  
Isolation And Identification ◽  
Microbiological Methods

Phyllosphere—the harsh foliar plant part exposed to vagaries of environmental and climatic variables is a unique habitat for microbial communities. In the present work, we profiled the phyllosphere microbiome of the rice plants using 16S rRNA gene amplicon sequencing (hereafter termed metabarcoding) and the conventional microbiological methods (culturomics) to decipher the microbiome assemblage, composition, and their functions such as antibiosis and defense induction against rice blast disease. The blast susceptible rice genotype (PRR78) harbored far more diverse bacterial species (294 species) than the resistant genotype (Pusa1602) that showed 193 species. Our metabarcoding of bacterial communities in phyllomicrobiome revealed the predominance of the phylum, Proteobacteria, and its members Pantoea, Enterobacter, Pseudomonas, and Erwinia on the phyllosphere of both rice genotypes. The microbiological culturomic validation of metabarcoding-taxonomic annotation further confirmed the prevalence of 31 bacterial isolates representing 11 genera and 16 species with the maximum abundance of Pantoea. The phyllomicrobiome-associated bacterial members displayed antifungal activity on rice blast fungus, Magnaporthe oryzae, by volatile and non-volatile metabolites. Upon phyllobacterization of rice cultivar PB1, the bacterial species such as Enterobacter sacchari, Microbacterium testaceum, Pantoea ananatis, Pantoea dispersa, Pantoea vagans, Pseudomonas oryzihabitans, Rhizobium sp., and Sphingomonas sp. elicited a defense response and contributed to the suppression of blast disease. qRT-PCR-based gene expression analysis indicated over expression of defense-associated genes such as OsCEBiP, OsCERK1, and phytohormone-associated genes such as OsPAD4, OsEDS1, OsPR1.1, OsNPR1, OsPDF2.2, and OsFMO in phyllobacterized rice seedlings. The phyllosphere bacterial species showing blast suppressive activity on rice were found non-plant pathogenic in tobacco infiltration assay. Our comparative microbiome interrogation of the rice phyllosphere culminated in the isolation and identification of agriculturally significant bacterial communities for blast disease management in rice farming through phyllomicrobiome engineering in the future.

Sign in / Sign up

Export Citation Format

Share Document