The effects of fungicides on the phylloplane yeast populations of creeping bentgrass

The effects of fungicides on population size and the development of fungicide resistance in the phylloplane yeast flora of bentgrass was investigated. In the spring of 2001, azoxystrobin, chlorothalonil, flutolanil, and propiconazole were applied separately over a 6-week period to creeping bentgrass (Agrostis palustris Huds.). Total and fungicide-resistant yeast populations were assessed by dilution plating onto either potato dextrose agar or potato dextrose agar amended with the test fungicides. Total yeast populations in the fungicide- treated plots were significantly lower than the check plots on three out of four sample dates. In the fall, azoxystrobin or propiconazole were applied twice to the bentgrass over 3 weeks. Significantly larger total yeast populations were observed compared with resistant or highly resistant populations for each treatment on every sample date. Total yeast populations were significantly higher in the check plots compared with either the propiconazole- or azoxystrobin-treated plots on the first three of five sample dates. A collection of yeasts (N = 114) with no prior exposure to fungicides were more sensitive to chlorothalonil, propiconazole, flutolanil, and iprodione than a second group (N = 115) isolated from fungicide-treated turfgrass. These results suggest that fungicide resistance among phylloplane yeasts is widespread and could be an important factor in the development of biological control agents for turfgrass diseases.Key words: yeast, biological control, fungicide, resistance, phylloplane.

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

HortScience ◽

10.21273/hortsci15088-20 ◽

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.

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Variable adhesion and diurnal population patterns of epiphytic yeasts on creeping bentgrass

Canadian Journal of Microbiology ◽

10.1139/w05-145 ◽

2006 ◽

Vol 52 (5) ◽

pp. 404-410 ◽

Cited By ~ 6

Author(s):

Tom W Allen ◽

Leon L Burpee ◽

James W Buck

Keyword(s):

Creeping Bentgrass ◽

Field Trials ◽

Agrostis Palustris ◽

Initial Field ◽

Vitro Assay ◽

Yeast Community ◽

Epiphytic Yeast ◽

Nonadherent Cells ◽

Total Yeast

Irrigation and an in vitro agitation assay were used to determine the percentage of the epiphytic yeast community (Cryptococcus, Pseudozyma, Rhodotorula, and Sporobolomyces) adhering to the phylloplane of creeping bentgrass (Agrostis palustris (Huds.) Pers.). Colony-forming units (cfu) of total epiphytic yeast populations (adherent and nonadherent cells) and of adherent populations (cells not removed by agitation) were determined by leaf washing and dilution plating. In an in vitro assay, 40.0% and 57.1% of the yeast adhered to the leaves, whereas, in initial field trials the percentage of adherent yeasts ranged from 40.0% to 71.9% of the total population. Adherent yeast cfu on leaves in the morning were significantly lower on bentgrass (8.0 × 103to 3.1 × 104cfu·cm–2) compared with total yeast cfu (1.4 × 104to 4.7 × 104cfu·cm–2) on the nonirrigated control. No differences in yeast populations were observed between irrigated and nonirrigated plots 2 h after the 0900 treatments. Yeast populations followed a diurnal pattern, with larger cfu recovered from bentgrass leaves in the morning and significantly lower populations recovered in the afternoon. At 1400 the adherent yeast were 83.1%–100% of the total yeast population recovered from the leaves. The relative adhesiveness of the epiphytic yeast community on bentgrass leaves is dynamic with nonadherent cells making up a larger percentage of the population in the mornings than the afternoons.Key words: adherence, Cryptococcus, leaf surface, Rhodotorula, turfgrass.

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Suppression of Neonectria ditissima growth on agar by Bacillus-based products

New Zealand Plant Protection ◽

10.30843/nzpp.2017.70.107 ◽

2017 ◽

Vol 70 ◽

pp. 330

Author(s):

B.M. Fisher ◽

G. Gubellini ◽

P.N. Wood ◽

R.W.A. Scheper

Keyword(s):

Biological Control ◽

Colony Growth ◽

Potato Dextrose Agar ◽

Biological Control Agents ◽

Biological Product ◽

Apple Trees ◽

Biological Products ◽

Important Disease

European canker (Neonectria ditissima), is an important disease on apple trees. Four biological Bacillus-based products and four fungicidal products were tested for efficacy against this pathogen on water agar (WA) and potato dextrose agar (PDA). Neonectria ditissima colonies grown without the biological products were healthy, but when mixed with biological control agents, the colonies were smaller and more diffuse. An interaction between medium and product was observed at 20˚C. BacstarTM, SerenadeÂ® Optimum and TripleXTM reduced colony growth on PDA but not on WA, while FulzymeÂ® Plus reduced colony growth on WA but less on PDA. Interestingly, the efficacy of the products was not improved when 10 times label rates were used, except for Fulzyme Plus on WA. At 10˚C and 15˚C Fulzyme Plus was the most effective biological product, particularly at 10 times label rate. Activation of the biological products (25˚C for 3 h) did not increase their efficacy. CapetecTM (captan) and a mixture of HML32TM + HML SilcoTM prevented pathogen growth. ARMOUR-ZenÂ® and EsteemÂ® did not reduce the number of colonies. More research is needed to determine whether biological products can be used to control European canker.

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Use of TEM in Plant Disease Diagnosis: A Xylem-Limited Bacterium Associated with Diseased ‘Toronto’ Creeping Bentgrass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098575 ◽

1981 ◽

Vol 39 ◽

pp. 414-415

Author(s):

Karen K. Baker ◽

David L. Roberts

Keyword(s):

Osmium Tetroxide ◽

Plant Disease ◽

Leaf Tissue ◽

Infectious Agent ◽

Creeping Bentgrass ◽

Disease Diagnosis ◽

Unknown Etiology ◽

Agrostis Palustris ◽

Putting Greens ◽

Plant Disease Diagnosis

Plant disease diagnosis is most often accomplished by examination of symptoms and observation or isolation of causal organisms. Occasionally, diseases of unknown etiology occur and are difficult or impossible to accurately diagnose by the usual means. In 1980, such a disease was observed on Agrostis palustris Huds. c.v. Toronto (creeping bentgrass) putting greens at the Butler National Golf Course in Oak Brook, IL.The wilting symptoms of the disease and the irregular nature of its spread through affected areas suggested that an infectious agent was involved. However, normal isolation procedures did not yield any organism known to infect turf grass. TEM was employed in order to aid in the possible diagnosis of the disease.Crown, root and leaf tissue of both infected and symptomless plants were fixed in cold 5% glutaraldehyde in 0.1 M phosphate buffer, post-fixed in buffered 1% osmium tetroxide, dehydrated in ethanol and embedded in a 1:1 mixture of Spurrs and epon-araldite epoxy resins.

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Yellow Brazilian Pepper-tree Leaf Galler (suggested common name) Calophya latiforceps Burckhardt (Insecta: Hemiptera: Calophyidae: Calophyinae)

EDIS ◽

10.32473/edis-in1186-2017 ◽

2017 ◽

Vol 2017 (6) ◽

Author(s):

James P. Cuda ◽

Patricia Prade ◽

Carey R. Minteer-Killian

Keyword(s):

Biological Control ◽

North America ◽

Natural Enemies ◽

Host Plants ◽

Classical Biological Control ◽

Biological Control Agents ◽

Pepper Tree ◽

Brazilian Pepper ◽

Close Relatives ◽

Tree Leaf

In the late 1970s, Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), was targeted for classical biological control in Florida because its invasive properties (see Host Plants) are consistent with escape from natural enemies (Williams 1954), and there are no native Schinus spp. in North America. The lack of native close relatives should minimize the risk of damage to non-target plants from introduced biological control agents (Pemberton 2000). [...]

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