June 18, 2009

Disease favorable weather is here! Dollar spot on the rampage!  Note the four red boxes on the weekly risk assessment index chart from June 11 to June 17.  They indicate that from an environmental standpoint, dollar spot disease pressure was high.  Given the forecast, I would not be surprised to see two more red boxes added for June 18 and 19.  Remember that under these conditions, residual efficacy of fungicides is about 14 days.  So, if effective treatments were applied on June 10, your turf should be protected through this high disease pressure period.  However, if fungicides were last applied on June 5 or earlier, then turf is at risk of dollar spot breakthrough.

Check out the weather forecast on a regular basis.  When nighttime temperatures average 68 or higher and dew periods are lengthy (10 hours or more), then brown patch risk will be high.  If your greens are due for a fungicide treatment in the next few days, it would be advisable to use a combination product, or tank mix your favorite fungicides to cover both dollar spot and brown patch.