Kansas State University


K-State Turfgrass

Powdery mildew in turf

Turf powdery mildew thrives in shady sites during cool, humid weather. We have had a lot of cool, moist days with temps in the 50s and 60s which is perfect for powdery mildew. The disease is often temporary, disappearing when hotter, drier weather kicks in.

The following photos are courtesy of my excellent colleague Chuck Otte, County Extension Agent, Ag & Natural Resources, Geary County. He confirmed that the site is shady.

It’s a fescue/bluegrass blend. To my eye, it looks like the Kentucky bluegrass is affected more than the fescue.

This next photo is a super-zoom of powdery mildew through the microscope. The photo is from squash powdery mildew, not turf powdery mildew, but turf powdery produces similar structures – long chains of spores. The spores are blown by wind. When they land on a new, susceptible plant and IF conditions are right, they germinate and infect.

We see turf powdery mildew in spring and fall. A change to less humid, hotter weather will slow the disease.

Turf powdery mildew is one of the many diseases covered in the 2017 Turfgrass Fungicide Guide.

There are fungicides labeled, but for most of them little is known about the efficacy. The DMI fungicides have efficacy, but it can be hard to reduce disease once it is underway. Also, as I just mentioned, a shift in the weather will slow the disease. If a site has a chronic, ongoing powdery mildew options include improving airflow and sun exposure or renovating to a less susceptible type of turf or groundcover. Those cultural practices and site management tweaks are your best bet.

“In the event of a pesticide spill, follow the three Cs: CONTROL the spill, CONTAIN it, and CLEAN it up.”

Do you have a plan in place in case of a pesticide spill? You don’t want to be inventing your plan on the fly, in the moment.

Here at KSU in our research labs we go through “spill drills” each year to make sure we are ready, just in case. It’s not our favorite thing to do, but it means everyone knows what to do, just like a fire drill.

Here are some tips on pesticide spill procedures from U of Kentucky:

Dealing with Pesticide Spills

Emerald Ash Borer Workshop – Doniphan County, June 7

The Kansas Forest Service is sponsoring a workshop about EAB on June 7, 12:30-4:30 in Troy (Doniphan County). Topics include identification and biology, EAB quarantine rules, tree injection information, and more. Certified pesticide applicator and arborist credits are available.

Here is the link to the brochure:



There is a shorter, more general session in the evening:

Tree Field Day, Overland Park Arboretum, June 2

The Kansas Forest Service is hosting a tree event at the Overland Park Arboretum on Friday, June 2. It’s the Walnut Council Field Day, and usually the focus is more on rural trees. But, with the unique Overland Park location, some of the topics are right in line with urban trees, including tree identification and tree problems

Here is the registration form and full schedule:


Plants are good for people

I think we all know that plants and nature are good for people. However, to read more about the social side of the green industry you can check out this interesting article about “Trees, jobs, health, and equity in the urban forest.”

As the article says, “Even the smallest bits of nature in the city can make a positive difference in people’s daily lives.”

Here is the link:


Anthracnose in shade trees

Here is a quick update from Ward Upham and the Horticulture News:

We are starting to see anthracnose on sycamore. Anthracnose is a fungal disease favored by cool, wet weather. Young leaves may wither and turn black. On older leaves, look for brown areas that follow the major veins of the leaves. In some cases, the petiole (leaf stem) is infected, which causes leaf drop. The leaf may look perfectly fine, so look for browned areas on the petiole.
In severe cases, the tree drops heavily infected leaves and may be completely defoliated. Healthy trees will leaf out again in a few weeks. Defoliation this early in the year does not affect overall tree health. Trees have plenty of time to produce new leaves and make the energy reserves needed to survive the winter.
Other types of trees that are affected by anthracnose include birch, elm, walnut, oak and especially ash. Anthracnose seldom causes significant damage to trees in Kansas, so chemical controls are usually unnecessary. Also, fungicides do not cure infected leaves. Applying fungicides now will not help.


For a detailed overview of anthracnose diseases of shade trees, you can check out the free online pdf version of Diseases of Trees in the Great Plains. I’ve mentioned this book before – it is a great resource!  Here is the link, and the anthracnose part is the section section, on p. 22 of the pdf.

Anthracnose is also covered in our Tree and Shrub Problems of Kansas book.

Spring turf disease potpourri


Wet, cool weather is favoring continued activity of large patch and other spring diseases. If you have not downloaded it yet, be sure to check out the 2017 fungicide guide from Vincelli et al.

For a superb update on large patch, dollar spot, spring dead spot, and root problems, you can roll on over to the Missouri Turf Pathology Report .

Here is some large patch in our research plots:


Just for fun, here is some fairy ring activity. I walk past this spot a lot, and those mushrooms popped out after a recent rain.

And also just for fun here are two panoramas of Rocky Ford! You can click to zoom and imagine birds chirping and a soft spring breeze in the air… ahhhh….