When I arrived to work this morning I was greeted by an outbreak of dollar spot. We had been on the dry side since the last week June but we received 1.33 inches of rain yesterday. The abundant rainfall coupled with the warm overnight temperatures, and high humidity led to conditions that were very conducive for dollar spot. Mycelium was especially abundant in our untreated creeping bentgrass areas.
Below are a few pictures from one of our creeping bentgrass fairway trials. This particular trial has 24 different cultivars of creeping bentgrass. Each plot is split in half and is either untreated or receives applications of Daconil and Emerald.
The objective of the trial is the determine the susceptibility of creeping bentgrass cultivars to dollar spot when maintained under reduced fungicide applications. Applications of the Daconil and Emerald mixture are scheduled based on a threshold of dollar spot severity in a cultivar with a high level of dollar spot resistance. Declaration is the indicator cultivar in this trial.
This picture shows the Declaration plot in one of the replications. The left half of the plot is the treated side and before today had only received one application on June 6. Declaration is a recently developed cultivar of creeping bentgrass that has relatively high resistance to dollar spot compared with other cultivars. Even the untreated side (right side) is holding up fairly well without receiving any fungicide to date.
This next picture shows a Penn A-4 plot. Here the right half of the plot is the treated side. As you can see, there are noticeable differences between cultivars of creeping bentgrass with respect to their disease resistance.
This trial along with many others will be on display during the Iowa Turfgrass Institute/Iowa State University Field Day on July 21. There is still time to register for the event.