View Full Version : leaf wetness and disease prediction on turf grass

02-20-2001, 08:11 PM
any of you do any work on leaf wetness and turfgrass disease prediction.

Forever Green Lawn
02-20-2001, 11:56 PM
There are some computer models that predict diseases based on leaf wetness, air and soil temps, relative humidity, soil moisture and amount of rain. From what I've seen they over predict. As for us predicting a disease, you must keep several factors in mind, more that just leaf wetness. List what diseases are common on the lawns in your area for that season. Figure the weather conditions necessary and what the current weather is like. For example, Leaf spot (Bipolaris & Drechslera) is a common Kentucky bluegrass disease. You can start to see it in May if the weather has been wet and turns hot and humid and then rainfall occurs. It's most severe when the temps are in the 80's or higher. If the current weather matches up with the necessary weather for the disease, then you should be on the look out for it. This is by no means a fool-proof system. Some lawns will get the disease and others won't. Depends on many factors, like amount of thatch, shade, cultural practices, and other things. I hope this helps some.


02-22-2001, 09:17 PM
Water accounts for over three quarters of the quanitive weight of a grass plant. Imperative to the plants survival, a 10% reduction in water content is enough to cause injury and/or the death of the plant.
Between natural rain, dew, and proper irrigation, the plant spends much of its time wet. Most fungal activity requires water to complete its life cycle, and it goes without saying, if you are observing a stand of living turf the chances are good water's present.
Scott is correct. If the pathogen is present AND the conditions are right, infection WILL occur. It's better to keep your eye on the temperature. Snow mold does not occur in July and brown patch will not be found in March.

02-22-2001, 10:13 PM
thank you both for your replys...
they helped...

11-08-2001, 07:00 PM
got some new guys on this forum. what do you think.

11-11-2001, 08:36 PM
Try bent grass on a putting greens in the shade on a humid creek bottom in May through September You don't wait and watch, you get out your Visa card and blow 500 dollar chunks on fungicide every 2-3 weeks.

11-13-2001, 04:25 PM

07-21-2002, 08:52 AM
i reposted this
see if we can get more replys

07-21-2002, 09:48 AM
For an interesting computer model try www.btny.purdue.edu/Pubs/turfcast.fcgi Turfcast is a product of Purdue under the direction of Rick Latin. Makes for some interesting reading.

07-21-2002, 12:28 PM
thanks for the reply...what a great link...

Randy J
07-21-2002, 01:05 PM
Here's another link;
Greencast (http://www.greencastonline.com/index.asp)

And here's one for weeds;
Weed Alert (http://www.weedalert.com/index.shtml)


07-22-2002, 09:44 PM
Have a client that I maintain and fert and pulled up last week and seen big patches in her turf about 5' in diameter. It is Bermuda turf, the dead spots had an orange appearance to it. Checked for insects and found nothing. I took a sample down to my extension office and he put it under the scope and found she has Curvularia. A month ago we had little or no rain and then this month has been very wet. Having been paying attention around town it looks like many others have this disease.

Have also noticed that the dew starts about 10:00 pm and have been mowing turf still wet by 12:30 pm. Seems like a favorable condition for turf disease.

07-26-2002, 06:51 PM
Kansas State University did a really nice Brown Patch study a few years back in which they found a strong correlation between nightime wet blades and disease incidence. 10 hours of wet Tall Fescue seemed to be the critical threshold.

We are so over run with brown patch this summer, I can scarcely keep up with the calls. We are always looking for any cultrual practice to minimize this headache. Even if it's only a placebo ;) !!