Dollar Spot Forecasting

The weather is finally starting to warm up in the Midwest. I think we have turned the corner and left those nasty leaf spots behind us, hopefully. Now our attention turns to summer diseases. Dr. Derek Settle has seen foliar anthracnose on creeping bentgrass in Central Illinois and some pretty severe outbreaks of dollar spot in Central and Southern Illinois. Just this morning at the OJ Noer we saw small dollar spot infection centers on our Crenshaw fairway plots. The rest of the week's forecast is calling for mid 80's during the day and nighttime temperatures above 60 with high humidity. If you haven't made a fungicide application for dollar spot on fairways, you better do so this week.

I'm sure you can sense the excitement in my writing. I'm sure you are wondering why too. Well I was thinking that Wisconsin was not going to have a summer, but now I know that summer is on the way! I am excited because one of the projects we are doing in Wisconsin, in collaboration with Oklahoma State University, is developing a dollar spot forecasting model. Dr. Damon Smith initiated an experiment last year with the intent of modeling dollar spot development in the field. I was fortunate to see this experiment last year and Dr. Smith and I started to work together to pick apart the epidemiology of dollar spot. From his data last year, Dr. Smith determined that dollar spot will not develop until 5-day air temperatures reach or eclipse 57F and when relative humidity levels are above 70%. We have established plots with weather stations in Wisconsin to see if Dr. Smith's development data are similar to data collected in Wisconsin. He has constructed a preliminary model that we have begun to validate in Oklahoma and Wisconsin. Preliminary results indicate that the model accurately predicts dollar spot development in the field and therefore could help with timing fungicide applications targeting dollar spot.

During these tough economic times, a forecasting model for one of the most important turfgrass diseases will help to limit fungicide expenditures. Even saving a single application in areas that spray fairways will amount to a significant cost savings. Please stay tuned to see what unfolds with this project. In the meantime, my poor Cubbies could use some serious prayer time :)