Know thy Host, Know thy Disease

Know thy Host, Know thy Disease

Article first appeared in the Purdue Landscape Report, June 27, 2023 – Included in Issue: and is reprinted here with permission.

As we get into the throngs of summer, disease activity takes hold on the cool season turfgrass species we commonly use on lawns. This spring/early summer 2023 much of the state has been in a considerable drought, missing approximately two inches of normal precipitation in both April and May, and three inches below normal so far this June (see Midwest drought map here). Disease activity has been minimal to non-existent on unirrigated, brown and crunchy lawns, with most damage most likely occurring from unnecessary mowing traffic on non-growing grass. For irrigated lawns, the supplemental water avoids drought dormancy and potential thinning, but also provides the necessary leaf wetness and humidity for diseases to attack.

The two most common diseases on cool season lawns are dollar spot and brown patch. Dollar spot occurs most frequently on Kentucky bluegrass lawns, while brown patch is one of the few diseases that affect tall fescue. Therefore, knowing and being able to identify the grass species that makes up your lawn is an important aspect in caring for it. The first step in any of our lab diagnosis is identifying the plant host, or at least confirming the host listed on the diagnostic form is correct.

brown patch

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