Reflecting on Summer and Preparing for Winter Diseases

In Knoxville, Fall is definitely here. It's a great time to about how your summer program worked, and what changes you might need to tweak to get it to work better next year. Do that now, and you will be ahead of the folks down the street.

This year was relatively mild for us in the transition zone, and in our programs trial we saw this by seeing most programs perform relatively well on common summer diseases like dollar spot, brown patch and anthracnose. However, most programs don't have more than one or two phosphate applications as a part of their regular sequence and it became apparent that to battle Pythium diseases it is important to consider what you are going to rely upon for controlling these diseases. We continued to confirm that using a program that applies DMI and strobilurin fungicides early in the summer is tremendously important to maintaining high season-long quality. In our programs we had those two important modes of action going down in the first application at the beginning of June, and it set those programs on a course to have one of the best turf quality ratings throughout the season. These programs also were in the category of having the least amount of disease throughout the season.

We also saw that every fungicide program has weaknesses. It is important to remember that when a fungicide program is designed, it generally focuses on the major issues that particular species of grass faces, and tries to control them. It doesn't cover everything under the sun. As I mentioned, one of the glaring weakness in most fungicide programs is the lack of sufficient Pythium control applications. The reason for this is that weather conditions conducive for Pythium blight just don't happen all season long. We also saw weaknesses in mid-summer with dollar spot control in programs that made the assumption of a normal summer when dollar spot is not usually present. In those programs we observed greater than usual dollar spot pressure because of the unusually cool, wet weather that we had. This is why it is good to have options on hand so that if you see weather forecasts suggesting certain conditions might be conducive for a disease, then you can go ahead and make an application for protection. Another weakness that we observed in this wet summer was the importance of using chlorothalonil (Daconil) for algae control. Any of the programs that used moderate rates in order to remain below the seasonal caps saw significant reductions in the amount of algae in those plots. Where chlorothalonil wasn't used, there was rampant invasion by algae because of the wet weather that occurred. Weaknesses are inevitable, and there aren't any 'bulletproof' programs, so the key question is what you can do to minimize them.

October and early order season is right around the corner, and next summer is only eight months away, so plan improvements now. Also, keep in mind that winter diseases can affect warm-season grasses. Spring dead spot and large patch are both diseases that if you have bermuda or zoysia, you should start monitoring the weather for the first applications of those products. Apply these soon in order for high effectiveness. Especially with the cool, wet weather we've had this summer, it wouldn't surprise me if we have a cool, wet fall that large patch pressure could be quite intense. We have already had some reports of symptoms of large patch on some slow growing zoysia, so keep a good watch on the weather and prepare to pull the trigger on preventative applications early!