So long, summer

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August 1, 2017 -  By

As summer winds down, LCOs should focus on repairing the damage caused by months of hot, humid weather.

Fall is a time of renewal for turf. So as summer winds down, lawn care operators (LCOs) should focus on repairing the damage caused by months of hot, humid weather. For cool-season grasses, fall is the time for LCOs to fertilize, seed and aerate. Jamie Breuninger, field scientist with Dow AgroSciences, says this gives the turf two seasons — fall and spring — to prepare for summer stress. For Bermudagrass and warm-season grasses, fall is the time for LCOs to think about controlling winter annual weeds.


Headshot: Jamie Breuninger

“When Bermudagrass goes dormant, the weeds are very prominent — you have brown turf and green weeds and customers don’t like it,” says Breuninger. “For warm season grasses you want to think about the timing of your Poa annua preemergent products, as well as fall and early-winter broadleaf control programs.”

Breuninger says timing is important for herbicide applications to be effective, adding that it’s not uncommon for LCOs to begin their broadleaf control efforts too early when temperatures are still high in late summer or to begin them too late and miss the window for Poa annua control. But for LCOs who find themselves in this situation, Breuninger says Defendor specialty herbicide is one product that’s effective for broadleaf weed control in the late fall or in the early spring in cool temperatures should weeds appear at this time of the year.

“Fall is a great time for broadleaf weed control because you get warm days and cool nights. The weed plant is storing energy and sending it down below to its crown and roots and the herbicide is moving with it,” he says. “If you do a really good fall weed control program, it reduces the amount of broadleaf weeds in the spring.”

One common mistake LCOs make in late summer is trying to prevent crabgrass from going to seed through use of postemergent crabgrass herbicide applications to reduce the seed bank for the following year, which Breuninger says is not a very effective strategy. He says the better way to combat crabgrass is to try to improve the overall health and density of the turf through fertilization and seeding and then use an effective preemergent crabgrass product in the spring.

Images: Dow AgroSciences Turf & Ornamental

Images: Dow AgroSciences Turf & Ornamental

“One crabgrass plant can create 10,000 seeds and can be viable for two and a half years, so trying to control the crabgrass seed bank is not an effective way to go,” he says. “Crabgrass needs light to germinate, so if you have a really thick turf it won’t have a chance to take hold.”

Peter Landshoot, Ph.D., professor of turfgrass science and director of graduate studies in agronomy at Penn State University, agrees that establishing healthy turf is the most effective way to prevent weeds and other problems.

“The most effective means of controlling summer annual grassy weeds is through cultural measures that create a dense turf — such as fertilization, proper mowing and pest control — and the use of preemergence herbicides in the spring,” he says. “When these measures fail, postemergence herbicides can be used.”

John Buechner

John Buechner

John Buechner, director of technical services for Lawn Doctor, a lawn care company headquartered in Holmdel, N.J., with franchises throughout the U.S., says it’s important for LCOs to communicate with their customers and to set proper expectations about their lawn care services.

“One of the major misconceptions is that we can control anything the customer perceives to be a weed,” he says. “However, there are some grassy weeds that we can’t get rid of without killing the whole lawn. Customers need to be educated as to what can and can’t be accomplished.

“During late summer, many areas experience heat stress and drought, which can cause lawns to go dormant due to water restrictions or lack of irrigation,” Buechner adds. “Customers need to be reassured that this dormancy protects the lawn, and that it will recover.”

LCOs also should instruct clients about proper watering and mowing practices. Buechner suggests LCOs minimize applications of weed control products in hot weather and emphasize the customer’s role in proper mowing and watering to keep lawns healthy.

“From the customer perspective, proper watering in hot, humid conditions is really important to reduce incidents of fungal disease. Homeowners can make a brown spot worse and spread the disease by watering too much,” Buechner says. “The key is communication with customers, because we are in a stressful time of year. If you see problems you have to let them know what will happen.”

Unmasking the Myths

Peter Landshoot

Peter Landshoot

Peter Landshoot, Ph.D., professor of turfgrass science and director of graduate studies in agronomy at Penn State University in University Park, Pa., debunks some common lawn care myths and sets the record straight.

Myth 1: Synthetic lawn fertilizer (urea- and ammonium-based products) and pesticides kill off microbial communities and sterilize soil in lawns.

“This notion is sometimes promoted by organic purists, but it’s a myth,” Landshoot says. “Numerous studies have been conducted on turf soils treated for years with all sorts of synthetic fertilizer and pesticides, and these soils have plenty of microbial activity. In fact, microbes are primarily responsible for breaking down certain pesticides and many fertilizers.”

Myth 2: Applying gypsum will break up clay soils and reduce compaction in cool-humid portions of the country.

“This is true in arid regions, like the southwestern U.S. But if sodium levels in soil are high, it’s not the case in humid regions of the country, such as the northeast U.S.,” Landshoot says. “Sodium levels in clay soils where rainfall is about 40 inches per year are typically very low — certainly not high enough to cause soil dispersion and destruction of soil structure. The only way to improve compaction due to traffic on clay soils is to break up the soil with an aerator or other mechanical cultivating machine. Adding organic matter, such as good quality compost, will help create aggregation, larger pores and reduced compaction.”


Images: Dow AgroSciences Turf & Ornamental

Myth 3: All lawns need to be limed every year.

This is true if the soil has a pH below optimum, but the only way to know if this is the case is to take a soil test,” Landshoot says. “Lots of soils don’t need lime, and over-liming can lead to nutrient availability problems down the road. Presence of moss is not necessarily an indicator of low pH (high soil acidity); moss can and does grow on soils with an optimum pH as well. Be sure to look at all factors that encourage moss, such as shade, poor drainage, overwatering/excessive rainfall and poorly-adapted turfgrass species. All moss needs to grow is moisture and a little bit of bare soil.”

Myth 4: Moles tunneling in lawns are a sign of grub activity.

“Yes, moles eat grubs and other insects if they are present, but most of their diet is composed of earthworms,” says Landshoot. “Moles are more of a problem when properties border wooded areas and in new lawns that have been recently tilled. Tunneling is often most visible in late winter/early spring, long before grubs have made it to the surface to feed. In most cases, applying a grub treatment when moles are actively tunneling is not an effective means of getting rid of moles.”

Myth 5: Castor oil, chewing gum, sonic devices, pinwheels and other household products kill or drive moles away.

“The best way to get rid of moles is to trap them,” says Landshoot. “However, this requires proper placement of traps, timing and vigilance. If you are lucky enough to know a good mole trapping expert in your area, this is your best bet.”

Myth 6: Returning grass clippings to the lawn will increase thatch.

“Grass clipping are mostly composed of water and compounds that are easily decomposed,” Landshoot says. “Thatch is mostly stems (including rhizomes and stolons), crowns and some root material.”

Images: Dow AgroSciences Turf & Ornamental

About the Author:

Emily Schappacher is a freelance writer based in Cleveland.

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