Though we are now in the window for maximum broadleaf weed control and fall fertilization, the dry weather throughout most of the state is hampering applications.
Avoid herbicide and/or fertilizer application to drought stressed or dormant turf to limit turf damage and maximize intended effect of the application.
On turf that’s still green (like in most of Indiana), dry weather reduces effectiveness of broadleaf herbicide applications and more importantly, can increase the burn potential of these applications on desired turf. Burn potential from these herbicides increases with temperatures beyond 80F as well as with additions to the spray tank like urea. Since broadleaf weed control will be effective until the end of October, consider holding off on these applications until rains begin again.
September is the most important month to fertilize any cool-season turf stand. However, the effectiveness and turf safety of fertilizer applications are always enhanced by irrigation or rain shortly after the application to move the fertilizer to the soil. This is especially important with liquid applications. Therefore, professionals should hold off on liquid applications of fertilizer to non-irrigated areas or consider using a granular fertilizer instead. The granular fertilizer will limit burn potential compared to a sprayable and though rain is still necessary to maximize the effect of granular products, it is not as crucial with a granular fertilizer as it would be with sprayables.
Send corrections, suggestions, and comments to biehlj@purdue.edu