Dollar Spot (Sclerotinia homoeocarpa) Control Using Organic and Synthetic Fungicide Combinations.

Abstract

 Dollar spot S. homoeocarpa is one of the most destructive diseases turf managers face annually. Warm and cool season grasses throughout the world are susceptible to S. homoeocarpa. The purpose of this study was to evaluate organic fungicides, combinations of organic fungicides and combinations of synthetic and organic fungicides on their efficacy of S. homoeocarpa. Evaluation began on May 20, 2009. Grasses evaluated were Agrostis stolonifera L. var palustris (Huds). cultivars L-93 and Crenshaw. Products being evaluated were: Daconil ultrex (Chlorothalonil), Headway (Azoxystrobin + Propiconazole), Insignia (Pyraclastrobin), Rhapsody (Bacillus subtilis), EcoGuard (Bacillus licheniformis), Paradigm (Clove oil, Wintergreen oil, Rosemary oil), Plant Shield (Trichoderma harzianum) and Mycostop (Streptomyces griseoveridis). Applications of fungicide programs were made every 14 days.

 Nitrogen was applied at 4 pounds per 1000 ft² annually. Nutrients were supplied via organic and inorganic based products. Granular products and liquid products were used during this study. Additional phosphorus, potash and iron were applied through separate products to provide the 1-1-2 ratio of N-P-K. Granular products include Novozymes endoROOTS 3-3-4 and 13-0-26 from Harrell’s Fertilizer. Nature Safe is comprised of hydrolyzed feather meal, meat meal, bone meal, fish meal and langbeinite.  Novozymes Turf Vigor 9-3-6 active ingredients include oilseed extract, ammonium nitrate, urea, ammonium phosphate, potassium phosphate, potassium sulfate and ammonium sulfate. Parkway Research 7-0-14 supplied the inorganic liquid nitrogen.

 This project was an 8 by 2 factorial with 8 fungicide programs tested on 2 different fertility programs. Test plots measured 1.5 meters by 1.5 meters. LSD was calculated using Fisher’s LSD, alpha 0.05. Repeat treatments and additional screening of products will be continued for timing and control of S. homoeocarpa.