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The Floods of 2010

August 13, 2010

This is a week that people in Central Iowa will not forget for a long time. Ames received around 10 inches of rain in a three day period and the city experienced arguably its most devastating flood ever. The Squaw Creek and Skunk River are the two major waterways that run through town. Squaw Creek crested at 18.13 feet (flood stage is 9) which was just shy of the record crest of 18.5 experienced back in 1993. The Skunk River crested at 26.52 feet (flood stage is 20) which was above the 1993 crest of 25.53 feet. For those familiar with Ames, the picture above is a shot of Hilton Coliseum inundated in flood waters.

The majority of the flood waters have now receded and cleanup efforts are well underway. Trying to predict the survival of turfgrass in flooded conditions is tricky business and depends on so many factors. Weather is a big factor and has not been on our side so far this week. Temperatures have been in the low 90’s with the humidity pushing heat indices into the 100’s.

We were greeted to a healthy dose of mycelium at our research station this morning. During my time spend in industry, I learned that trying to visually distinguish between dollar spot and pythium blight is very difficult (at least it is for me!) so we brought the sample to campus for a closer look. Inspection of the sample under a compound microscope confirmed that the disease we were seeing was in fact Pythium blight.


We also stumbled upon some slime mold. Earlier in the year we had a post about slime mold on green height creeping bentgrass. This slime mold appeared on rough height Kentucky bluegrass. Remember that slime molds are more of an oddity, they’re unsightly but they are not considered harmful and control measures are not necessary.

I’ll leave you with a video courtesy of KCCI News Channel 8 showing an aerial view of the city this past Wednesday morning.


Potential for Late-Season Pythium

August 29, 2013

With the Iowa temperatures expected to continue in the upper 90’s with high humidity for the foreseeable future, it presents conditions conducive to Pythium blight activity. Pythium is known as one of the most destructive turf diseases in the Midwest and overnight it can lead to large turf death. With most turf managers fungicide programs winding down for the year; it might be the time to have a bottle of Cyazofamid (Segway®) handy for a knockdown contact application. 

Pythium is a high temperature disease which presents the most damage under daytime temps in excess of 86⁰F, followed by nights in the high 60's. It usually affects close-mown turfgrass under intense management. Symptoms generally include small circular patches (1-2 inches) accompanied with a cotton-like mycelia that appears in the early morning. Pythium is often first noticed on sites with poor drainage. It is also easily spread by mechanical means and can be carried over turf by foot traffic and/or mowing equipment.  Reducing your nitrogen fertility inputs, avoiding night watering, increasing air movement, and improving areas with poor drainage reduces your threat for disease incidence.

Below are some pictures of the cotton-like mycelia seen in the early morning.



August 26, 2010

I have looked at a number of lawns this year that looked like they had been damaged by Pythium Blight. I was always there after the fact, however, and was unable to diagnose it for sure. Pythium on golf course turf is a common problem, but it is fairly rare on lawns.

Here are some pictures from Jorden Kolpin in the plant and insect diagnostic clinic at Iowa State. These are pictures showing the mycelia early in the morning on Kentucky bluegrass lawns in Iowa. These have been verified to be Pythium by the lab.

This disease is also called "Cottony Blight". You will be able to see why in the pictures. The mycelia generally go away in mid day. Jorden makes a positive identification by looking under the microscope. The individual hypha lack cross walls and spores of the Pythium are generally present.

The hot, wet conditions are what brought this on. Wet conditions, with night temperatures above 68 F and hot days are required for its development. The problem should be over for the season, but watch for it next year.



August 5, 2010

The two pictures below are from Tim Christians at Makray golf course in Chicago. It has been very wet there and night temperatures have been high. He is seeing a lot of Brown Patch on greens and Pythium on bluegrass along the fairways. The fairways are bentgrass and they have been treated with phosphites to prevent Pythium. He is reporting a lot of success with phosphites the last two years for Pythium controls. I was a little nervous about relying on phosphites, but I cannot argue with success.

I had some other calls about brown patch earlier in the week. We had a lot of brown patch at the research station in June, but I usually don't expect it in early August. By Thursday, however, we were seeing a lot of brown patch on our bentgrass cultivar trial at the station as well. It must be the saturated conditions.

For some reason we are getting surprisingly little dollar spot at the station this summer. Last year we had plots loaded with dollar spot all summer. This year I had graduate student Derek York start a study on dollar spot. As would be expected, we have almost no dollar spot in the study area. Next year we'll do a study on saturated soil conditions and we'll get a drought.

I can report that our crabgrass work is doing extremely well at the research area this summer.

I have had a lot of questions on water grass lately from homeowners. As many of you know, there is no such thing as water grass. They are generally referring to crabgrass and other annuals that take over in wet weather. There are a lot of people out there who did not put on a preemerge this spring and are interested in the services of a good lawn care company next year.