scholarly journals A Dimorphic and Virulence-Enhancing Endosymbiont Bacterium Discovered in Rhizoctonia solani

2017 ◽  
Vol 1 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Ken Obasa ◽  
Frank F. White ◽  
John Fellers ◽  
Megan Kennelly ◽  
Sanzhen Liu ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Dna Analysis ◽  
Higher Plants ◽  
Intracellular Localization ◽  
Creeping Bentgrass ◽  
Single Species ◽  
Cool Season ◽  
Plant Host ◽  
Brown Patch ◽  
Bacterial Endosymbionts

The ubiquitous soilborne and plant-pathogenic basidiomycete Rhizoctonia solani, although classified as a single species, is a complex of anastomosis groups (AGs) that cause disease in a broad range of higher plants. Here, we investigated the persistent co-isolation of bacteria with R. solani from brown patch-infected, cool-season turfgrasses, and report the presence of endo-hyphal bacteria, related to members in the genus Enterobacter, in an isolate of R. solani AG 2-2IIIB. The intracellular localization of the bacteria was corroborated by fluorescence, confocal and electron microscopy, and DNA analysis. Furthermore, the Enterobacter sp., which is rod-shaped in the free-living form, exists as an L-form (spheroid) within the fungus, a phenomenon not previously reported in endosymbionts. Our findings also indicate that the bacterium is required for full virulence of R. solani on creeping bentgrass and production of wild type levels of the toxin phenylacetic acid in fungal cultures. The possible presence of bacterial endosymbionts in R. solani AG 2-2IIIB may portend the presence of bacteria in additional AGs as well as other Rhizoctonia species, and may help resolve some of the complexities of R. solani pathogenicity. A closely associated bacterium could influence aspects of plant host pathology.

scholarly journals Brachypodium: A Potential Model Host for Fungal Pathogens of Turfgrasses

2017 ◽  
Vol 107 (6) ◽  
pp. 749-757 ◽  
Author(s):  
Renee A. Rioux ◽  
Benjamin J. Van Ryzin ◽  
James P. Kerns
Keyword(s):  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Brachypodium Distachyon ◽  
Creeping Bentgrass ◽  
Sclerotinia Homoeocarpa ◽  
Dollar Spot ◽  
Cool Season ◽  
Host System ◽  
Brown Patch ◽  
Compatible Interactions

Brachypodium distachyon is a C3 grass that is an attractive model host system for studying pathogenicity of major turfgrass pathogens due to its genetic similarity to many cool-season turfgrasses. Infection assays with two or more isolates of the casual agents of dollar spot, brown patch, and Microdochium patch resulted in compatible interactions with B. distachyon inbred line Bd21-3. The symptoms produced by these pathogens on Bd21-3 closely resembled those observed on the natural turfgrass host (creeping bentgrass), demonstrating that B. distachyon is susceptible to the fungal pathogens that cause dollar spot, brown patch, and Microdochium patch on turfgrasses. The interaction between Sclerotinia homoeocarpa isolates and Brachypodium ecotypes was also investigated. Interestingly, differential responses of these ecotypes to S. homoeocarpa isolates was found, particularly when comparing B. distachyon to B. hybridum ecotypes. Taken together, these findings demonstrate that B. distachyon can be used as a model host system for these turfgrass diseases and leveraged for studies of molecular mechanisms contributing to host resistance.

scholarly journals Survival of Rhizoctonia solani AG2-2 IIIB Causing Brown Patch Disease of Creeping Bentgrass.

1999 ◽  
Vol 65 (5) ◽  
pp. 521-525
Author(s):  
Koji KAGEYAMA ◽  
Fumio KITAMURA ◽  
Taketo AOYAGI ◽  
Mitsuro HYAKUMACHI
Keyword(s):  
Rhizoctonia Solani ◽  
Creeping Bentgrass ◽  
Brown Patch ◽  
Patch Disease

scholarly journals Impact of Bispyribac-sodium Application on Annual Bluegrass Control and Brown Patch Severity in Tall Fescue

2012 ◽  
Vol 30 (4) ◽  
pp. 195-200
Author(s):  
Matthew Cutulle ◽  
Jeffrey Derr ◽  
Adam Nichols ◽  
David McCall ◽  
Brandon Horvath
Keyword(s):  
Rhizoctonia Solani ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Iron Supplementation ◽  
Field Research ◽  
Field Trials ◽  
Control Field ◽  
Brown Patch ◽  
Annual Bluegrass ◽  
Application Rates

Annual bluegrass (Poa annua L.) is a problematic weed in tall fescue [Festuca arundinacea (Schreb.) S.J. Darbyshire], with limited options available for postemergence control. Field research was conducted to evaluate bispyribac-sodium application rates (37 or 74 g ai·ha−1) (0.033 or 0.066 lb ai·A−1) and timings (March, April or May) as well as iron supplementation on brown patch (Rhizoctonia solani) severity, annual bluegrass control, and tall fescue quality. In general, applying bispyribac-sodium to tall fescue did not result in significantly more brown patch than in untreated plots in field trials. Applying bispyribac-sodium in March or April resulted in significantly higher annual bluegrass control than applications in May. In greenhouse experiments, bispyribac-sodium at 37 and 74 g ai·ha−1 (0.033 or 0.066 lb ai·A−1) was applied to brown patch-inoculated tall fescue plants. Under conditions of high inoculum and humidity in those greenhouse studies, applications of bispyribac-sodium increased the number of brown patch lesions relative to untreated plants. Tall fescue plant height was initially reduced after being treated with bispyribac-sodium; however, six weeks after application tall fescue plants in treated with herbicide were taller than the nontreated plants.

Absorption, Translocation, and Metabolism of Amicarbazone in Annual Bluegrass (Poa annua), Creeping Bentgrass (Agrostis stolonifera), and Tall Fescue (Festuca arundinacea)

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Jialin Yu ◽  
Patrick E. McCullough ◽  
William K. Vencill
Keyword(s):  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Creeping Bentgrass ◽  
Agrostis Stolonifera ◽  
Poa Annua ◽  
Physiological Effects ◽  
Cool Season ◽  
Foliar Absorption ◽  
Annual Bluegrass

Amicarbazone controls annual bluegrass in cool-season turfgrasses but physiological effects that influence selectivity have received limited investigation. The objective of this research was to evaluate uptake, translocation, and metabolism of amicarbazone in these species. Annual bluegrass, creeping bentgrass, and tall fescue required < 3, 56, and 35 h to reach 50% foliar absorption, respectively. At 72 h after treatment (HAT), annual bluegrass and creeping bentgrass translocated 73 and 70% of root-absorbed14C to shoots, respectively, while tall fescue only distributed 55%. Annual bluegrass recovered ≈ 50% more root-absorbed14C in shoots than creeping bentgrass and tall fescue. Creeping bentgrass and tall fescue metabolism of amicarbazone was ≈ 2-fold greater than annual bluegrass from 1 to 7 d after treatment (DAT). Results suggest greater absorption, more distribution, and less metabolism of amicarbazone in annual bluegrass, compared to creeping bentgrass and tall fescue, could be attributed to selectivity of POST applications.

Fungicide Management of Brown Patch of Tall Turf-type Fescue in the Residential Landscape in Oklahoma

2013 ◽  
Vol 14 (1) ◽  
pp. 4
Author(s):  
Damon L. Smith ◽  
Nathan R. Walker
Keyword(s):  
Transition Zone ◽  
Tall Fescue ◽  
Cultural Practices ◽  
Warm Season ◽  
Kentucky Bluegrass ◽  
Cool Season ◽  
Brown Patch ◽  
Lawn Care ◽  
The Usa ◽  
Residential Market

In the transition zone of the USA, cool-season grasses such as tall fescue are often planted in shaded areas, where warm-season grasses are less adapted. The most damaging disease of tall fescue is brown patch, caused by Rhizoctonia solani. Fungicide applications and cultural practices are often used to manage brown patch in this region. A three-year study was implemented in Oklahoma to evaluate ready-to-use fungicides available to residential lawn owners and compare these to several common commercial fungicide formulations used by professional lawn care applicators. A selection of fungicides representing products commonly available to the residential market and commercial standards were applied to small plots of tall fescue or tall fescue/Kentucky bluegrass mixtures from 2008 to 2010. All products tested, with the exception of azoxystrobin, provided limited or inconsistent control of brown patch and resulted in lower turfgrass quality in all years. Further examination of carrier type (granular vs. liquid) and timing (preventive vs. curative) did not result in strong differences in the level of brown patch control or overall quality. These studies suggest that control of brown patch in tall fescue in the transition zone should focus on integrated disease management principals and not only on applications of fungicides directed at the residential market. Accepted for publication 5 August 2013. Published 22 October 2013.

scholarly journals Physiological Basis for Metamifop Selectivity on Bermudagrass (Cynodon dactylon) and Goosegrass (Eleusine indica) in Cool-Season Turfgrasses

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 12-24 ◽  
Author(s):  
Patrick E. McCullough ◽  
Jialin Yu ◽  
Mark A. Czarnota ◽  
Paul L. Raymer
Keyword(s):  
Laboratory Experiments ◽  
Cynodon Dactylon ◽  
Retention Factor ◽  
Creeping Bentgrass ◽  
Kentucky Bluegrass ◽  
Shoot Biomass ◽  
Cool Season ◽  
Physiological Basis ◽  
Eleusine Indica ◽  
Treated Leaf

Bermudagrass and goosegrass are problematic weeds with limited herbicides available for POST control in creeping bentgrass. Metamifop effectively controls these weeds with greater selectivity in cool-season grasses than other ACCase inhibitors. The objectives of this research were to determine the physiological basis for metamifop selectivity in turfgrasses. In greenhouse experiments, metamifop rate required to reduce shoot biomass 50% from the nontreated (GR50) at 4 wk after treatment was > 6,400, 2,166, and 53 g ai ha−1for creeping bentgrass, Kentucky bluegrass, and goosegrass, respectively. The GR50for bermudagrass treated with diclofop-methyl or metamifop was 2,850 and 60 g ha−1, respectively. In laboratory experiments, peak absorption of14C-metamifop was reached at 48, 72, and 96 h after treatment (HAT) for goosegrass, creeping bentgrass and Kentucky bluegrass, respectively. Grasses translocated < 10% of the absorbed radioactivity out of the treated leaf at 96 HAT, but creeping bentgrass translocated three times more radioactivity than goosegrass and Kentucky bluegrass. Creeping bentgrass, Kentucky bluegrass, and goosegrass metabolized 16, 14, and 25% of14C-metamifop after 96 h, respectively. Goosegrass had around two times greater levels of a metabolite at retention factor 0.45 than creeping bentgrass and Kentucky bluegrass. The concentration of metamifop required to inhibit isolated ACCase enzymes 50% from the nontreated (I50) measured > 100, > 100, and 38 μM for creeping bentgrass, Kentucky bluegrass, and goosegrass, respectively. In other experiments, foliar absorption of14C-metamifop in bermudagrass was similar to14C-diclofop-methyl. Bermudagrass metabolized 23 and 60% of the absorbed14C-diclofop-methyl to diclofop acid and a polar conjugate after 96 h, respectively, but only 14% of14C-metamifop was metabolized. Isolated ACCase was equally susceptible to inhibition by diclofop acid and metamifop (I50= 0.7 μM), suggesting degradation rate is associated with bermudagrass tolerance levels to these herbicides. Overall, the physiological basis for metamifop selectivity in turfgrass is differential levels of target site inhibition.

Selective Nimblewill (Muhlenbergia schreberi) Control in Cool-Season Turfgrass

2007 ◽  
Vol 21 (4) ◽  
pp. 886-889 ◽  
Author(s):  
John B. Willis ◽  
Josh B. Beam ◽  
Whitnee L. Barker ◽  
Shawn D. Askew ◽  
J. Scott McElroy
Keyword(s):  
Initial Treatment ◽  
Creeping Bentgrass ◽  
Single Application ◽  
Cool Season ◽  
Selective Control ◽  
Control Options

Isoxaflutole and mesotrione have been used to control creeping bentgrass in cool season turf, these experiments evaluate these two products for selective nimblewill control. Three experiments were conducted in Virginia and Tennessee to evaluate selective control options for nimblewill in cool-season turfgrass. Single applications of isoxaflutole control nimblewill more effectively than single applications of mesotrione. Nimblewill control 8 wk after initial treatment (WAIT) increased as mesotrione rates increased from 28 to 280 g ai/ha, and isoxaflutole rates increased from 28 to 168 g/ha. Isoxaflutole at 84 and 168 g/ha were the only single application treatments that controlled nimblewill greater than 80% 8 WAIT. However, sequential applications of isoxaflutole and mesotrione at 28 g/ha, 10 d apart controlled nimblewill 94 and 80%, respectively 8 WAIT. Triclopyr and fenoxaprop-p did not effectively control nimblewill and caused unacceptable turfgrass injury. Long-term control was not evaluated in these studies. However, it was concluded that isoxaflutole and mesotrione at appropriate rates and applied in sequence selectively control nimblewill without harming desirable turf.

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