Knowledgebase
Lawn Disease Identifier and Solution #876709
Asked July 10, 2024, 3:40 PM EDT
Hello,
I recently developed some turf disease over the last few days here on my lawn in Northern Colorado (loveland) and was wondering if you could help identify it and tell me how I should go about treating it. It came on rather quickly over the course of a few days. At first I suspected Ascochyta Leaf Blight but as I inspected the blades I didn't notice any blades with brown middle section and green top/bottom section still intact. Also, the dead/Brown grass lifts right out of the soil with no resistance at all. I then immediately thought Pythium but the grass doesn't feel greasy, have any odd color other than brown and I haven't noticed any white moldy/web like growth. I am attaching a few pictures for reference. If you need more I am more than happy to take any you may need or even send in a sample. Thanks in advance and help would be greatly appreciated!
Larimer County Colorado
Expert Response
Pictures added
Pictures added
We rarely see Pythium in home lawns, so we can rule that out. It might be Ascochyta, but I can't see enough of the lawn to make that decision.
A couple recommendations to start:
1. Mix up some soapy water (a few drops per gallon) and pour it on some of the brown spots. Look for any grubs that may rise to the surface.
2. Do an irrigation audit to rule out irrigation as a potential cause. When the system it running, it always looks like water is going everywhere, but our eyes can't see inefficiency or gaps in coverage. Since 95% of our turf problems are linked to irrigation issues, this is an important one to rule out.
- Put out several (10-12) cups of uniform shape and size in an irrigation zone. You can use tuna cans, yogurt cups, etc. Be sure to place some in the green spots and some in the brown spots.
- Run the system for 15-20 minutes.
- While the system is running, look carefully at the heads. If there are heads that are crooked (even slightly), not popping up fully, or at an angle, flag those heads to adjust later.
- After the system runs, measure the water in the cups and compare the output. Are the thin spots getting less water? Even a slight difference of 0.10" can lead to INCHES over a growing season (and we've had a lot of hot and dry weather, so these areas would brown out more quickly). Do the thin/brown areas correspond to any heads that are crooked or not popping up fully?
- Adjust your heads. Make sure they are rising above the turf surface, have a good angle, the pattern applies water evenly, and they are nice and straight.
- Set out the cups again after your adjustments and run the system again. See if you have improved outputs that are more even.
- Measuring your output will help determine how long you need to water each week in minutes. If you get 1/4" of irrigation in 20 minutes, then you'll get 3/4" in 60 minutes. So to apply 1.0" of water, you'll need to water a total of 80 minutes during the week. This might mean two, 40-minute cycles or 3, 26-minute cycles. The seasonal needs of typical bluegrass are:
- April: 0.5"/week (this includes precipitation too!)
- May: 0.5-1.0"/week
- June: 1.0"/week
- July: 1.0-1.5"/week
- August: 1.5"/week
- September: 1.0" week
