Crop Science (2007) 47, 1206-1216

B.J. Horvath, A.N. Kravchenko, G.P. Robertson and J.M. Vargas Jr. (2007)
Geostatistical analysis of dollar spot epidemics occurring on a mixed sward of creeping bentgrass and annual bluegrass
Crop Science 47 (3), 1206-1216
Abstract: Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) causes one of the most important diseases faced by golf course superintendents throughout the USA. Fungicides are effective, but fungicide resistance and regulation have restricted their use. Site-specific application allows more judicious use of fungicides, but the spatial heterogeneity of dollar spot incidence has been unknown. An intensive study was designed to determine the spatial distribution of dollar spot incidence using geostatistical analysis. Dollar spot foci were manually counted every 2 to 3 d in 200 quadrats in 2000, and in 888 quadrats in 2001 and 2002. Variograms showed spatial aggregation of dollar spot foci on a small scale, and remained stable throughout the growing season despite increasing disease incidence. The range parameter of the variograms was stable within a season, with values ranging between 2.5 and 9.5, 1.3 and 1.9, and 1.2 and 2.2 m in 2000, 2001, and 2002, respectively. Kriged maps of dollar spot incidence also show a stable pattern of spatial aggregation remains throughout the growing season. The locations of dollar spot clusters changed between seasons, but the variograms from each season were similar, further suggesting stability of the spatial structure. It appears that limited secondary dispersal of S. homoeocarpa occurs during epidemics, as evidenced by the stable variograms observed throughout the three growing seasons. The underlying factors involved in the observed stability are unknown.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Brandon J. Horvath

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
transmission/dispersal of plant diseases

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Clarireedia homoeocarpa	Agrostis (crop)