7/2/2013 - By Dr. Raymond Snyder

Disease outbreaks can happen so fast. For this reason, disease management on golf course putting greens often requires the use of dual strategies in order to minimize the effects of fungal pathogens. A multi-pronged disease management program includes the use of both preventative and curative fungicides. Implementing multiple strategies helps to reduce the development of a disease epidemic when environmental conditions are often unpredictable and the presence of fungal pathogens waiting for an opportunity to exploit vulnerable turf is certain.

December of 2006 provided a classical case study of how unfavorable environmental conditions contributed to the rapid development of a disease epidemic in south Florida. Primary factors that affect disease development are temperature, moisture, and light. An unexpected and unfavorable combination of all three factors came together the weekend of December 16, 2006 to negatively impact bermudagrass putting greens throughout south Florida. A cold front that had moved through the area earlier in the week stalled just off the coast and began to retreat, resulting in overcast skies with warm, moist air enveloping the region over the weekend. Compounding these unfavorable atmospheric conditions was the general absence of experienced onsite turf managers because of weekend scheduling and holiday travel plans. A situation for the perfect storm for disease development resulted.

The use of preventative fungicides prior to the onset of the unfavorable conditions observed the weekend of December 16, 2006 generally helped to reduce disease symptoms on golf course putting greens as observed by turf managers and other turf industry professionals. Chipco Signature (fosetyl-Al) alone and in combination with other fungicides, such as Cleary’s 3336 (thiophanate methyl) and Heritage (azoxystrobin) proved valuable in reducing visible disease symptoms relative to untreated greens. In addition, those turf managers who observed disease symptoms on morning of December 16 and were able to make fungicide applications with Subdue Maxx (mefenoxam) also saw reduced symptomatic conditions.

Turf managers who were not able to apply preventative fungicides prior to the unfavorable environmental conditions were left with severely damaged putting surfaces as a result of significant fungal pathogen activity. Valiant efforts were made in vain by many after the weekend with contact fungicides such as Daconil Zn (chlorothalonil), even though the unfavorable environmental conditions had significantly improved and further disease activity was unlikely. Samples of diseased grass were sent to various labs for analysis. In most cases Pythium was determined to be the primary cause of turf decline.

In conclusion, the use of preventative fungicides can prove to be a valuable tool in reducing disease activity. Determining when to apply preventative fungicides is often a matter of scientific study, experience, and unique circumstance. One thing for certain, discovering that a preventative fungicide should have been applied is humbling.