Turf Tips - Lawn Diseases 2016

The summer of 2016 has been quite favorable for the development of an assortment of infectious diseases on residential turf. The primary driver of all of this disease activity is the weather. In the lower Midwest, the combination of elevated temperature and ample precipitation since the beginning August of has spawned outbreaks of brown patch, dollar spot, Pythium blight, leaf spot diseases, and the appearance of symptoms of summer patch and necrotic ring spot. Although infection is almost entirely a function of temperature and moisture, there are other factors (addressed in the linked blog post) that may hasten the decline of turf once disease becomes established.

Not all turf species are susceptible to all diseases. In general, Kentucky bluegrass (KBG) is less prone to brown patch , dollar spot, gray leaf spot, and Pythium blight—but very susceptible to root diseases such as necrotic ring spot and summer patch. Root pathogens are present in all soils, and infect turf as soil temperatures increase beyond 60F. With ample moisture, infection will continue through summer. Plants are killed outright in some instances, but in most cases, KBG can tolerate some infection. However, during periods of environmental stress, infection-impaired plants cannot survive, and characteristic dead patches or rings or frog-eyes appear.

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Rick Latin, Ph.D.
Professor of Plant Pathology
Purdue University

Your Browning Lawn - To Water or Not?

Meander through any Hamilton County neighborhood today to take note of the varying degree of browning of the non-irrigated lawns. We can speculate why some lawns have fared better than others (higher mowing heights, proper seasonal fertilization, better soil conditions, etc.) but exact reasons remain unclear. One major factor affecting that effects lawn survival during extended dry periods is supplemental irrigation or rainfall in your area. Lets look at how a homeowner knows it is time to take the next step and irrigate their lawn to prevent permanent damage from these dog days of summer.

Most lawns in our region primarily contain cool-season grasses that grow best when the air temperatures are between 60 and 80 degrees F. Well cared for mature grasses can tolerate extended dry periods. When these dry periods are coupled with higher temperatures, there can be additional physiological stresses which can be irreversible.

Water should be applied only when lawns show signs of moisture stress. During this time, one may notice a bluish gray tint to blades; footprints that remain some time after walking; and wilted or curled leaves are indications that it is time to water. At this point a delay in watering can result in permanent damage unless you have decided to allow the lawn to go dormant.

Established lawns should be irrigated with 1 inch of water every week to ten days to keep it growing actively. I prefer early morning watering because it reduces the risk of disease, water loss through evaporation, and improper water distribution. If you decide to allow your lawn to go dormant, irrigate every two weeks with 1/2 inch of water.  This strategy allows the turf to go dormant but will keep the plant crowns hydrated during drought. If you need some help determining whether your lawn is dead or has transitioned into dormancy, click here for a good article with pictures to help your decision.  

Exerts taken from the following Extension Publications.  Click links below for more information. 

Purdue Turf Program: Summer Drought Info

Home Lawns During Drought