The KSU Turfgrass Pages

TITLE: Preventive Fall Fungicide Applications for Control of Rhizoctonia Large Patch Disease of Zoysiagrass

OBJECTIVE: To determine whether fall fungicide applications help suppress development of large patch of zoysiagrass caused by Rhizoctonia solani

PERSONNEL: Ned Tisserat

SPONSORS: Ciba, PBI Gordon, Rhone Poulenc, AgrEvo, Bayer, Rhom & Hass, Sandoz, Zeneca, Heart of America Golf Course Superintedent's Association, Kansas Golf Course Superintendent's Association, and the Kansas Turfgrass Foundation.

MATERIALS AND METHODS:

A section of zoysiagrass 'Meyer' at the Highlands Golf Course in Hutchinson, KS was used for the experiment. Fungicides were applied on 27 September 1995. Plots were placed in a fairway with a history of large patch, although no symptoms of the disease were apparent at the time of fungicide application. Individual plots were 10 X 12 feet and replicated three times. Fungicides were applied in 2 liters of water/120 sq ft at 30 psi with 8003 flat fan nozzles using a CO2 backpack sprayer. Plots were not watered immediately after fungicide application.

RESULTS:

The fall of 1995 was very dry, and large patch was not evident before the zoysiagrass went dormant. The winter also was very dry and cold. As a result, the turfgrass was slow to break winter dormancy (approximately 2 weeks later than normal). Large patch severity at the time of rating (1 May 1996) was considered to be moderate to light. Nevertheless, nontreated plots averaged 28% of the plot area damaged. No evidence was seen of active colonization of the turfgrass by the fungus, suggesting that most turf damage was a result of late fall infection.

Several fungicides significantly reduced severity of large patch (Table 1). Plots treated with Prostar, Lynx, Heritage, Sentinel, Bayleton, Penstar, or Banner plus Medallion had little or no large patch. Plots treated with Sentinel appeared to be slower to break winter dormancy and were slightly off-color (lighter green). Results for the past several years indicate that a preventive fungicide treatment in the fall is effective in suppressing both fall and early spring symptoms of patch.

Table 1. Preventive fungicide applications for control of large patch of zoysiagrass, 1995-1996.

* Fungicide application on 6 Nov 95
** Ratings taken on 14 Mar 96. Percentage data were given an arcsine square root tranformation for analysis and backtransformed for presentation. Means not followed by the same letter are significantly different (P= 0.05)