Source: www.TurfMagazine.com
Management strategies to help lawns recover and avoid future damage
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Summer scorched its way across the Midwest this summer, leaving in its wake shattered weather records. Ohio, for example, broke a 113-year-old record for the least rain in August: .37 inch for the month. The state recorded nine days over 90 degrees in July, versus none the prior year. There were eight more days that topped 90 in August. The National Weather Service reported that this was the fourth hottest ever recorded in Detroit, which saw 69 days over 80 degrees. Surrounding states saw much of the same.
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The shattered records, in turn, led to tattered lawns. Turfgrass struggled to keep up with the hot, dry conditions, and many lawns failed. “We have some lawns that are in pretty tough shape,” said Jeff Benton with St. Clair Lawn Services in St. Clairsville, Ohio, in early September. “It’s spotty. We have some areas that aren’t as dry, but we have other areas that are horribly dry.”
Benton hoped the grass on the hardest hit lawns was simply dormant, and it would come back with cooler fall weather and a little rain. St. Clair Lawn Services applies fertilization on lawns, and he adjusted applications. “We’ve used a lot of dry, slow-release product, and hopefully it will be there when we do get adequate moisture to kick in and help get bring the lawns back,” he said.
The company’s fall maintenance work also has been dictated in some regards by the hot, dry weather and the condition of many yards. “We’re busy doing some slice seeding, overseeding and some aeration to help out those lawns,” he stated.
Richard Hentschel, extension specialist for green industry programming with the University of Illinois Extension, says that the damage seen during the summer was exaggerated by the wet conditions that preceded it. “Earlier in the season, we had a boatload of water, and then the faucet turned off,” he says. “All of the patch diseases were everywhere, and then things dried off and went dormant. Without those diseases, lawns would have been healthier and stronger ahead of the dry weather, so the recovery would have been much better. Instead, many lawns are looking really, really thin.” Those lawns that were treated for disease earlier in the season have fared much better, he adds.
In fact, says Hentschel, there is a lesson to be learned from the damage done by the dry weather: management practices matter. “Many communities these days have watering bans and restrictions—not just in bad years, but even in good years,” says Hentschel. “People who watered when they could may have been able to keep things from going dormant, or if the lawn went dormant at least keeping enough water on them to keep the crowns alive and the root systems turgent. And, they likely saw a better recovery.”
Watering isn’t the only turf management practice that can help protect lawns in prolonged dry periods and help them recover. “There are still many lawns being mowed shorter than they should be,” observes Hentschel. “Sometimes in dry conditions, lawns are mowed whether they need it or not.” To make matters worse, in near-dormant conditions the height of cut is even lowered just to make sure the appearance of a freshly mowed lawn is evident afterwards. “That’s just detrimental,” he states. In addition to damaging the grass plant, low mowing is also likely to increase weed pressure. “Many weed seeds need sunlight to germinate, and when you open up the soil to more sun exposure by mowing short, you’re just asking for more weeds to germinate.”
Not surprisingly, areas of lawn with southwest exposures have fared worse than grass with north and east exposures. “That’s one of the environmental factors that we sometimes forget to take into account,” says Hentschel. Sometimes, during extremely hot spells, only certain portions of lawns might need to be mowed, he adds.
The effects of heat and drought are likely to be more evident on lawns cut with dull mower blades, says Hentschel. “When you cut the grass blade off, it has to heal. Dull blades just shred the top and make it difficult to heal. You’re also introducing many times more surface area to disease infestation,” he says.
Further, lawns with heavy thatch often have grass root systems growing at least partially in that thatch instead of in soil, which makes the plant more vulnerable to heat. “That doesn’t help, because once the thatch dries out, there’s no choice for that turf plant but to go dormant,” explains Hentschel.
Lawns left thin and bare due to the summer weather likely will need some seeding. “It’s important to use hybrid, disease-resistant varieties of seed,” says Hentschel. Sod typically comes with this built-in protection, but some lower-quality seed should be avoided. “With seed, you get what you pay for,” he says. “When you’re reseeding, the diseases are already there, just waiting for an opportunity, so you need to use disease-resistant grasses.” Using seed with three to five different types of grasses in a mix also reduces the risk of one variety being susceptible to a particular disease.
When possible, Hentschel recommends fall rather than spring seeding in order to address thin spots on lawns that have been damaged. “Fall provides a much longer window for establishment than spring. It warms up so soon in the spring that you’re quickly back into the heat. “If you’re going to reseed in the spring, you have to forgo crabgrass preventive treatment in those areas,” he cautions. “If you seed in the spring, you’ve prepared a nice seed bed not only for the grass, but also for weeds, so you’re going to get a lot of weeds. Don’t panic, just wait to deal with them the following fall.” It’s better to tolerate weeds in order to get the newly planted lawn established than to risk damaging the tender grass plants by treating for weeds.
Regardless of when lawns are seeded, after patch diseases, heat or other factors have killed an area of the lawn, there’s likely to be small, sunken areas. “Those depressed areas in the lawn are where water is going to stand,” says Hentschel. “I always advise adding a little topsoil to those damaged areas to bring them up to grade, even if it’s just .25 inch. If you let rain or irrigation water stand in those spots, you’re just asking for all of the diseases to come right back in.” If an area was damaged so heavily that it is resodded, it’s still important to be sure the grade of the new area matches that of the existing lawn in order to avoid puddling situations.
Because it’s impossible to know when external factors such as hot, dry conditions will appear, it’s important to take charge of the things you can control. “You can control three things with mowing: you can control the frequency, how high you set your mower deck and the sharpness of your mower blades. Those three things alone will have people wondering what miracle product you’re using on the lawn.”
Fall fertilization is also helpful, giving the grass strength to come out of the winter and be ready for the natural spring flush of growth. “This year, I would recommend a ‘winterizer’ fertilizer, designed to rebuild root systems and crowns, and to hopefully provide a little phosphorus and potassium to help the grass be disease resistant,” he says. Fertilizing in the spring can exaggerate the natural growth that already happens at that time of the year, leading to excess growth and, once that tall grass has been mowed short, potentially weakening the grass plant and making it more susceptible to disease or damage, depending on what weather comes along next year.
Patrick White is a freelance writer and editor who has covered every aspect of the green industry in the past 13 years. He is based in Middlesex, Vt., and is always on the lookout for unusual stories.