Control of Dollar Spot Disease (Sclerotinia homoeocarpa) of Bentgrass Green Turf with Urea

Abstract

Chiba Prefectural Government has examined on the establishment of the measures for maintaining golf turf without using chemicals. Several nitrogen fertilizers were applied for dollar spot caused by Sclerotinia homoeocarpa on severely diseased bent green nursery which has been maintained without fungicides. Mycelial growth of dollar spot fungus on potato sucrose agar (PSA) medium amended with nitrogen fertilizers at the rate of 0, 0.5, 1, 2, 3, 4, 5% (w/v) gradually declined with increase of nitrogen fertilizer concentration and reached zero more than 0.5% ammonium carbonate and 5% of urea. In the field experiment on the bentgrass with severe symptoms of dollar spot disease, application of urea at high concentration of 200 l/ha of 50kg-N/ha and low concentration of 30, 000 l/ha of 50kg-N/ha at the intervals of 30 days also showed the same efficacy as application of benomyl of 2, 000-fold solution (0.5g ingredient per 1 liter) with the same volume of the high concentration application, ammonium sulfate and calcium nitrate showed pretty low efficacy with the high concentration and clearly low efficacy with the low concentration. Application of urea with high concentration is considered to be practical.