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Heat Plus Moisture Equals Fungal Disease

Actinovate Can Suppress the Worst Lawn Problems

Lawns are naturally waving their brown flags these days in the face of record heat in many parts of the country. “Cool-season” grasses — fescues, ryegrasses, bentgrasses and bluegrasses — just don’t like it one bit when the thermometer stays consistently above 90 degrees Fahrenheit.

Dollar spot

Dollar spot

The natural response to all this heat is for the lawn to go dormant, or turn brown, and shut down photosynthesis. The grass isn’t dead; it’s just sleeping away the hot season. Our natural response is to add water, often in the evening when we get home from work, which creates the ideal recipe for fungal diseases like dollar spot, fusarium blight, brown patch and others. These can create all manner of less than attractive appearance of the turf and, from the amount of calls we’re getting lately, all sorts of anxiety.

The good news with the vast majority of fungal diseases is that they’re rarely lethal and they almost always go away when the weather patterns change.

In some cases, though, you’ll want to take action by applying a fungicide, which is a product designed to kill the fungal spores that cause the disease. The only one we recommend applying at SafeLawns is Actinovate, which was created from a naturally occurring soil organism. Here’s the fact sheet: This product also works great on other garden plants, which can suffer this time of year from black spot, powdery mildew and fungal disease issues of their own.

Applications of Actinovate aside, here are some basic cultural techniques to explore.

Proper Fertilization – Lawns may be weakened by lack of the proper fertility and/or organic matter. Though fertilizing in the heat isn’t recommended, it’s not a bad idea to pull a soil test right now with the Cooperative Extension service at your state university or some other qualified agency. If the nutrients are lacking, fertilize this fall to address the deficiencies.

Mowing Practices – Mower blades can spread diseases from spot to spot on your own lawn, or from your lawn care guy’s last customer to your lawn. Be sure to wipe blades clean if you’re mowing over a diseased area — and insist that your hired landscaper clean his or her blades prior to cutting your lawn. Let the grass grow taller than usual, up to 4 inches high.

Watering – If you water this time of year, try to keep it to two times per week maximum and always water as early in the morning as possible, just prior to dawn even, so that the grass is as dry as possible heading toward evening.

Repair — At this point, wait until fall if possible. Any attempt to overseed or plant new plugs or sod will imprison you to a summer of daily watering — which might bring disease pressure to areas not already affected.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1023
  • Diane M Olson Schmidt

    In Southeast and southcentral Wisconsin, we’re seeing tons of disease problems when people water–overwater their lawns, especially lawns with irrigation systems. Despite the education out there, most lawn care services cut the lawns too short and cut every week whether lawns need cutting or not, which allows lots of weed seedlings to take hold and in sustainable and organic lawn care, makes it harder to maintain and folks trying out the organic lawn care usually turn back to the conventional lawn care as a result. Only 1″ of water a week is needed on lawns, enough lawn companies are not leaving clippings on the lawns.
    By educating the customers, repeating the messages over and over, will help, when customers start asking more questions from their lawn care services will get the message. Diane LaceWing Gardening Services, Milwaukee Wisconsin.

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