Last week we talked about the damage that insects can do to your lawn, today I’d like to talk about the dead or dying spots caused by fungus. As before, the best way to diagnose those problem spots in your lawn is to bring in a telephone book-sized piece of sod that includes the transition from healthy to unhealthy turf. You can always plug it back in later.
As we talked about before, insects go for the roots, which makes it easy to pull the grass plants out of the turf—fungus damages the above ground plant structure. Insect damage usually starts near a drive or sidewalk where paving creates heat and starts insect growth early in the season, fungus damage often shows patterns in the turf. Either will continue to do damage if left untreated.
Fungus kills turf indirectly by growing into the xylem (water conditioning cells), which are the cells that move water from the roots to the blades. It often shows up in hot weather when the need for water is highest in the blades.
It’s difficult to know which fungus is attacking your lawn without running some pretty time consuming and expensive tests, so we usually recommend a broad spectrum fungicide such as Fertilome F*stop or Bayer Fungus Control for Lawns. It’s best to attack the fungus when nighttime temperatures are consistently above 50F and daytime temperatures are consistently below 90F. Spores are often dormant below 50F and you could damage your turf if you apply the fungicide and the temperature exceeds 90F. Three applications made between 15 and 30 days apart seems to work best. The second and third application can wait until next spring—if you start in the fall. You don’t need to treat the entire lawn, just the affected areas with a two-foot or more buffer zone. The damaged tissue will disappear as the blades grow and you mow the lawn.
For additional tips to keep your lawn healthy, stop by any Western Gardens and we’ll share how to keep your lawnmower from spreading fungus, how much water is enough, and how high you should really cut your grass. Also, don’t forget to read the directions on the fungicide. Sometimes they change and the label directions will be the most accurate.
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