scholarly journals Variation Among Creeping Bentgrass Cultivars in Recovery from Epidemics of Dollar Spot

Plant Disease ◽  
1997 ◽  
Vol 81 (1) ◽  
pp. 99-102 ◽  
Author(s):  
P. Vincelli ◽  
J. C. Doney ◽  
A. J. Powell
Keyword(s):  
Partial Resistance ◽  
Creeping Bentgrass ◽  
Weather Conditions ◽  
Disease Outbreak ◽  
The Other ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Fungicide Treatment ◽  
Recovery Pattern ◽  
Host Growth

Dollar spot was allowed to develop from natural inoculum in 15 cultivars of creeping bentgrass (Agrostis palustris) until epidemics were well established. At that time, initial disease intensities were assessed, and one-half of each plot was treated with cyproconazole at 0.3 kg a.i./ha. For each cultivar, disease intensities were assessed 6 to 14 days after treatment in both treated and untreated subplots. Three general patterns of recovery were observed: (i) significant recovery only with fungicide treatment; (ii) some recovery without treatment but greater recovery with treatment; and (iii) equal recovery with or without treatment. Only one cultivar exhibited the same recovery pattern in all 3 years; 10 of 15 cultivars exhibited the same pattern in 2 years of testing. In 1991 and 1993, nearly all cultivars tested recovered more quickly when treated with cyproconazole than when left untreated. In contrast, nearly half of the cultivars in 1992 exhibited the same level of recovery in both treated and untreated subplots. Weather conditions during the 1992 test period were cooler and wetter than during the other years of the study, which probably favored host growth and turfgrass recovery. While some cultivars exhibited partial resistance to dollar spot, no consistent association was found among creeping bentgrass cultivars between the level of partial resistance to, and recuperative ability from, dollar spot. Although the recuperative potential of cultivars varies in different environments, the ability to recover quickly from a disease outbreak could be a valuable cultivar attribute, particularly if it can sometimes occur without a curative fungicide application.

RELATIONSHIP BETWEEN WEATHER FACTORS AND DOLLAR SPOT OF CREEPING BENTGRASS

1984 ◽  
Vol 64 (1) ◽  
pp. 167-174 ◽  
Author(s):  
ROBERT HALL
Keyword(s):  
Disease Control ◽  
Creeping Bentgrass ◽  
Weather Conditions ◽  
Acceptable Level ◽  
Sclerotinia Homoeocarpa ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Weather Factors ◽  
Average Temperature

In 1981 and 1982 epidemics of dollar spot of creeping bentgrass, caused by Sclerotinia homoeocarpa, proceeded in a series of steps. Each step began at a point where a decline in the epidemic rate was followed by an increase in the epidemic rate and continued until a new step began. A step in the epidemic occurred after two consecutive wet days if the average temperature for the period was at or above 22 °C or after three or more consecutive wet days if the average temperature for the period was 15 °C or greater. These weather conditions were referred to as "infection periods." In 1982, an application of Tersan 1991 (benomyl) 1 and 2 days after two infection periods provided an acceptable level of disease control as effective as that obtained from a regular preventive schedule of seven sprays.Key words: Agrostis palustris, disease control, Sclerotinia homoeocarpa, weather-timed spray

scholarly journals Use of the growth regulator paclobutrazol in the management of dollar spot of creeping bentgrass in Minnesota

2005 ◽  
Vol 80 (2) ◽  
pp. 65-70 ◽  
Author(s):  
J. Mercier
Keyword(s):  
Disease Control ◽  
Growth Regulator ◽  
Creeping Bentgrass ◽  
Poa Annua ◽  
Base Line ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Annual Bluegrass ◽  
Growing Seasons

The control of dollar spot by paclobutrazol applied as a growth regulator on a creeping bentgrass (Agrostis palustris) and annual bluegrass (Poa annua) fairway turf was compared with two standard fungicide treatments in Minnesota during two growing seasons. Paclobutrazol was applied every 3 weeks, staggered by about 10 days with fungicide treatments (chlorothalonil or propiconazole), also applied every 3 weeks. Paclobutrazol alone significantly reduced the number of dollar spot infection centers during both summers, often by as much as 80%. Chlorothalonil or propiconazole were usually more effective in controlling dollar spot than paclobutrazol. Paclobutrazol improved disease control by fungicides when tested in combination with various rates of chlorothalonil or propiconazole. Paclobutrazol applied as a growth regulator could thus be used to reduce the base line severity of dollar spot of turf.

Dollar Spot in Four Bentgrass Cultivars as Affected by Acibenzolar-S-Methyl and Organic Fertilizers

2003 ◽  
Vol 4 (1) ◽  
pp. 5 ◽  
Author(s):  
Joon Lee ◽  
Jack Fry ◽  
Ned Tisserat
Keyword(s):  
Organic Fertilizer ◽  
Creeping Bentgrass ◽  
Organic Fertilizers ◽  
Sclerotinia Homoeocarpa ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Putting Greens ◽  
Brown Patch ◽  
Growing Seasons ◽  
Progress Curve

Golf course superintendents are interested in identifying ways to reduce fungicide inputs on creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objectives were to evaluate the influence of the plant defense activator acibenzolar-S-methyl (ASM, Actigard, Syngenta Corp., Basel, Switzerland) and organic fertilizers on dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in four bentgrass cultivars. Crenshaw had over 10 times the area under the disease progress curve (AUDPC) value for dollar spot compared to the cultivar L-93 in 2000. Acibenzolar-S-methyl applied at 35 g a.i. per ha every 14 days between mid-May and mid-September for two consecutive growing seasons reduced the number of S. homoeocarpa infection centers by 15% in Crenshaw, 24% in Penncross, and 29% in Providence, but had no effect on the number of infection centers in L-93. Only Sustane (Crenshaw in 2000) and Milorganite (Crenshaw and Providence in 2001) suppressed dollar spot compared to urea. The following fertilizers resulted in an increase in S. homoeocarpa infection centers: Nature Safe 8-1.3-4.2 in Crenshaw in both years, and in Providence in 2000; Nature Safe 10-0.9-6.6 in Crenshaw in both years; and Sustane with Iron in Crenshaw in 2001. All other organic fertilizer × cultivar combinations resulted in dollar spot levels equivalent to those observed in ureatreated turf. Brown patch levels were not affected by cultivar, ASM, or organic fertilizers. The defense activator ASM deserves further evaluation as a tool to reduce dollar spot-targeted fungicide inputs in creeping bentgrass. Accepted for publication 5 June 2003. Published 26 June 2003.

scholarly journals Dollar Spot and Brown Patch Incidence in Creeping Bentgrass as Affected by Acibenzolar-S-Methyl and Biostimulants

HortScience ◽  
2003 ◽  
Vol 38 (6) ◽  
pp. 1223-1226 ◽  
Author(s):  
Joon Lee ◽  
Jack Fry ◽  
Ned Tisserat
Keyword(s):  
Experimental Design ◽  
Plant Defense ◽  
Cultural Practices ◽  
Creeping Bentgrass ◽  
Sclerotinia Homoeocarpa ◽  
Agrostis Palustris ◽  
Dollar Spot ◽  
Putting Greens ◽  
Brown Patch ◽  
Turf Quality

There is interest in identifying cultural practices that may reduce fungicide requirements of creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objective was to evaluate the plant defense activator ASM in combination with 12 biostimulants for the potential to reduce dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in a blend of `Cato: `Crenshaw creeping bentgrass during 2000 and 2001. The experimental design was a split-plot with ASM as the whole plot, and biostimulants as the subplots. ASM was applied biweekly as a.i. at 35 g·ha-1 and biostimulants were applied according to manufacturers recommendations. Sclerotinia homoeocarpa infection centers were reduced by 38% with ASM, but levels were >1500/m2 in Aug. 2000, and turf quality was unacceptable through most of the study period. No suppression of brown patch occurred with ASM. None of the biostimulants reduced dollar spot or brown patch in creeping bentgrass when compared to biweekly applications of soluble N at 4.9 kg·ha-1. Dollar spot suppression achieved with ASM warrants additional studies to determine how it might be used to reduce fungicide inputs on creeping bentgrass putting greens. Chemical name used: acibenzolar-S-methyl (ASM).

scholarly journals Effects of Dew Removal and Mowing Frequency on Fungicide Performance for Dollar Spot Control

Plant Disease ◽  
2011 ◽  
Vol 95 (11) ◽  
pp. 1427-1432 ◽  
Author(s):  
Tanner C. Delvalle ◽  
Peter J. Landschoot ◽  
John E. Kaminski
Keyword(s):  
Severe Disease ◽  
Late Summer ◽  
Creeping Bentgrass ◽  
Weather Conditions ◽  
Threshold Level ◽  
Agrostis Stolonifera ◽  
Sclerotinia Homoeocarpa ◽  
Dollar Spot ◽  
Point Of Reference

Dollar spot (Sclerotinia homoeocarpa) is a severe disease problem on creeping bentgrass (Agrostis stolonifera) fairways. The objective of this study was to evaluate the effects of dew removal and mowing frequency on fungicide performance for dollar spot control. In 2009 and 2010, an experiment involving daily dew removal or no dew removal, mowing frequency (2, 4, and 6 days week–1), and fungicides (chlorothalonil, propiconazole, and iprodione) was conducted on creeping bentgrass maintained as a fairway. Daily dew removal resulted in fewer dollar spot infection centers (IC) compared with not removing dew during late summer 2009 and 2010 for all mowing-frequency and fungicide treatments. As mowing frequency increased from 2 to 6 days week–1, dollar spot IC decreased when averaged across all fungicide treatments. For all fungicides, daily dew removal increased the number of days needed to reach a 15-IC plot–1 point of reference when compared with fungicide treatments in which dew was not removed. The number of days required to reach 15 IC varied with fungicide, mowing frequency, and year the test was conducted. Results demonstrate that dollar spot control with fungicides can be extended when daily dew removal is employed and, in some cases, when mowing frequency is increased on dew-covered turf. Benefits of dew-removal practices on dollar spot and fungicide performance can vary with weather conditions, fungicide, threshold level, and possibly other factors.

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

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.

scholarly journals A Study of the Effects of Rain, Snow and Hail on the Atmospheric Electric Field near Ground

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 996
Author(s):  
Athanasios Karagioras ◽  
Konstantinos Kourtidis
Keyword(s):  
Frequency Distribution ◽  
Complex Structure ◽  
Potential Gradient ◽  
Weather Conditions ◽  
The Other ◽  
Fair Weather ◽  
Northern Greece ◽  
Rain Events ◽  
The Impact ◽  
Bounce Back

The purpose of the present study is to investigate the impact of rain, snow and hail on potential gradient (PG), as observed in a period of ten years in Xanthi, northern Greece. An anticorrelation between PG and rainfall was observed for rain events that lasted several hours. When the precipitation rate was up to 2 mm/h, the decrease in PG was between 200 and 1300 V/m, in most cases being around 500 V/m. An event with rainfall rates up to 11 mm/h produced the largest drop in PG, of 2 kV/m. Shortly after rain, PG appeared to bounce back to somewhat higher values than the ones of fair-weather conditions. A decrease in mean hourly PG was observed, which was around 2–4 kV/m during the hail events which occurred concurrently with rain and from 0 to 3.5 kV/m for hail events with no rain. In the case of no drop, no concurrent drop in temperature was observed, while, for the other cases, it appeared that, for each degree drop in temperature, the drop in hourly mean PG was 1000 V/m; hence, we assume that the intensity of the hail event regulates the drop in PG. The frequency distribution of 1-minute PG exhibits a complex structure during hail events and extend from −18 to 11 kV/m, with most of the values in the negative range. During snow events, 1-minute PG exhibited rapid fluctuations between high positive and high negative values, its frequency distribution extending from −10 to 18 kV/m, with peaks at −10 and 3 kV/m.

scholarly journals On the effect of postponing pregnancy in a Zika transmission model

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Edy Soewono ◽  
Glenn Lahodny
Keyword(s):  
Stochastic Analysis ◽  
Infection Intensity ◽  
Disease Outbreak ◽  
Recruitment Rate ◽  
The Other ◽  
Transmission Model ◽  
Basic Reproductive Ratio ◽  
Numerical Investigations ◽  
The Individual ◽  
Endemic State

AbstractWe construct a Zika transmission model to investigate the effect of postponing pregnancy on the infection intensity. We perform analytical and numerical investigations for deterministic and stochastic analysis to obtain the basic reproductive ratio, endemic state, probability of disease extinction, and the probability of outbreak. The results indicate that by reducing the pregnancy rate the mosquito-to-human ratio increases, and, consequently, the basic reproductive ratio increases. Simultaneously, the probability of disease extinction decreases, and the probability of disease outbreak increases. On the other hand, the endemic state of infected infants initially increases with the decrease of the pregnancy recruitment rate, up to a certain level, and decreases as the recruitment rate of pregnancy tends to zero. This work highlights that postponing pregnancy that gives the individual temporary protection for unexpected infected newborns may increase the population infectivity.

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