Purdue News
Purdue News
October 25, 1996
"Don't let a heavy layer of leaves build up on your lawn before winter," Reicher said. "Leaves on the turf can kill it by smothering it, just as if you left a piece of plywood laying on the yard too long. But it can also lead to a lawn disease known as 'snow mold.'"
If the layer of leaves on the lawn is light, most homeowners can solve the problem by mulching the leaves with a couple of passes with a lawnmower.
"For years we've told people they can mulch leaves and leave them on the turf, based on our knowledge about how turfgrass grows. Now we're actually doing a multi-year study to see if this works as well as we think. It's too premature to draw any conclusions, but what we've seen so far is that mulching leaves and leaving them on the turf doesn't do any harm and may have some surprising benefits," Reicher said.
Heavy layers of leaves will require raking, but the leaves still can be used as a mulch, Reicher said. "Many landfills won't take leaves anymore, which means that you have to find something else to do with them," he said. "They can be composted or used as a mulch on gardens."
Reicher reminded homeowners that leaves will compost more quickly if they are chopped or mowed into small pieces. "If you are using them as a mulch on the garden, you should also chop or mow the leaves into small pieces before you use them," he said. "Don't apply more than a three-inch layer of leaves on the garden, and when spring comes, be sure to till the leaves into the soil."
A heavy layer of leaves can cause snow mold, which is a fungal disease. "It's an unusual fungus, because it is most active at 32 degrees," Reicher said. "It will kill the turf and you'll not know it until next spring.
"Areas of the Midwest that get an exceptional amount of snow one winter can just get hammered by this fungus."
Loads of leaves aren't the only thing that can lead to snow mold: Tall grass at the end of the season can be a problem, too.
"It's best to leave your turfgrass at three inches through the winter," Reicher said. "If it gets to six or seven inches, it will flop over and allow the fungus to develop. If it's too tall now, it's still not too late -- it's OK to mow even though it's November or December."
During the 1960s and 1970s, many turf experts recommended "scalping" the yard before winter. Reicher said that's bad advice.
"Honestly, I can't imagine why they told people that," Reicher said. "Scalping might prevent snow mold, but it's really bad for the turf.
"The optimum photosynthesis in grass plants happens at 44 to 50 degrees, so they're active through November and December. Scalping lawns leaves less grass leaf surface for photosynthesis to occur, which means less food gets to the roots. In the long term, this is very damaging."
Other lawn and turf information, including weekly updates by Purdue turf experts, can be found on the Internet at https://www.aes.purdue.edu/agronomy/turf/turftips.htm
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Source: Zac Reicher, (317) 494-9737; e-mail, zreicher@dept.agry.purdue.edu
Writer: Steve Tally, (317) 494-9809; home, (317) 463-4355; e-mail, tally@ecn.purdue.edu
