Q: What does it mean when some of the grass develops a white cast on the blades? Also, do you know of an easier way to get mushrooms out of your lawn other than by getting down and cutting them out?
Understanding Powdery Mildew on Lawns
A: The dusty white coating you describe is a common lawn disease called powdery mildew. The grass will look like it has been dusted with flour. Heavily infected areas can actually turn yellow and die. Powdery mildew grows best in shaded areas and is more noticeable during times of higher humidity. It is found more often in shaded areas because of the poorer air circulation in such locations. Using shade-tolerant strains of grass can help the problem, as well as choosing grasses that are resistant to the fungus.
Causes and Prevention
One of the contributing factors in the disease taking hold can be from over-fertilizing. Too much nitrogen will cause a great deal of new growth, and it is this new growth that is very prone to attack from the powdery mildew. Cutting the lawn too short has also been shown to be a causative factor. While there are fungicides available for heavy infestations, chemical controls are not necessary.
Dealing with Lawn Mushrooms
The mushrooms are growing on an organic source below or on the surface. Most likely some decaying organic matter of some type. They are not harmful to the lawn. If you choose, you can work at removing the organic matter, such as dethatching the lawn, as the thatch might be feeding the mushrooms. There may be an old tree root or even construction debris that the mushrooms are growing on. I just kick mine over when I mow the lawn. They break down quickly. There are chemicals that will kill the mushrooms, but they are not necessary.
Fertilizer Timing Advice
Q: I have been using a slow-release fertilizer on my lawn, and I fertilized in May. Can you please tell me when I should be fertilizing again?
A: Many slow-release fertilizers are intended to last for 3 months, but I find with the ones I use they are usually good for about 2 months, depending on the amount of rain we get. I reapply my fertilizer in mid- to late July and find that is adequate.
I'll end this column with a quote from Alfred Austin, “The glory of gardening: Hands in the dirt, Head in the sun, Heart with nature. To nurture a garden is to feed not just the body, but the soul.”
Every week, Growing Things Outdoors runs online at edmontonjournal.com or, if you prefer an epaper format, epaper.edmontonjournal.com. Learn more by emailing your questions to filipskigerald@gmail.com, reading past columns or my book Just Ask Jerry. You can also follow me on X (Twitter) @justaskjerry01.
