Fall lawn care

By John Fulton

[August 04, 2008]  The time of year has arrived to put that final push on to prepare your lawn for the upcoming winter months. What you do now will have a big impact on how your lawn will look next spring. The timing of many of the treatments will begin in about a week, so now you'll have plenty of time to make your list and complete your shopping.

Keep mowing when the grass or weeds dictate mowing. The rule of thumb is to remove no more than a third of the leaf blade at any one time. This means that if your desired mowing height is 2 inches, you should be mowing when the grass gets 3 inches tall. No summer slump this year, due to all the rain. It figures that we mow every three days all summer long when gas is hovering around the $4 mark.

I have had some grub samples brought into the office this week. This means that the grubs are active. Grub problems are normally found first along walks, driveways or patios. The insecticide must get to where the grubs are, so make sure to water the liquid formulations in as soon as they are applied. The two widely available products are GrubX (halofenozide) and Merit (imidacloprid). Remember, the active grubs now are from the June bug, and we'll want to wait another two to three weeks before trying to apply grub treatments for the Japanese beetle grub. Carbaryl (Sevin) granules are an option for Japanese beetle grubs but don't work on the other species.

Yellow grass tops are visible in many areas. This tends to happen in very wet years when nitrogen is taken from the root area, and trees and shrubs grab available nutrients. In the past, treatments haven't had much effect in the current growing season. Next year you won't see the same problem.

Fall seeding of grass should be done between Aug. 15 and Sept. 10. This is a tried-and-true date, but the end of the world won't come about if you are a week later. The goal is to give the seed enough time to germinate and become established before bad weather arrives. Seed at the rate of 4 pounds of seed per 1,000 square feet on bare spots, or half that rate on overseedings.

If you have a compacted yard or have a deep thatch layer, these seeding dates also define ideal times to dethatch or aerate. Thatch layers should not be over one-half inch deep for optimum growing conditions. When aerating, make sure you use a core-type aerator.

Fall fertilization is also a good practice. If you haven't fertilized in the last month, consider applying a fertilizer treatment around Sept. 1. Use about 8 pounds of 13-13-13 fertilizer per 1,000 square feet of lawn. Try to avoid the high nitrogen fertilizers this late in the year. It's hard enough to keep up with the mowing as it is, and nitrogen promotes top growth. The even-analysis fertilizers will also promote root growth, which is what we want, going into the late fall and winter.

Crabgrass and other annual grass weeds can be seen about everywhere. They will die with the first frost, so treatment is not available or recommended in the fall. Make a note of where these grasses are, and an overseeding to thicken up the grasses you want there may help crowd out the annuals. Preventive treatments may also be applied in the spring (around April 1, depending on soil temperatures) to kill the germinating seeds.

Last, but not least, is broadleaf weed control. Fall is a particularly good time to treat problem perennial weeds since they are sending food down to the roots to overwinter. A spray about the third or fourth week of September (making sure to use the appropriate product) can do a world of good on the perennial weeds. Remember to be very careful with herbicides around perennial plants since they are also getting ready to overwinter. Also, waiting this late in the season reduces drift potential for the neighbor's garden. With hot, sunny conditions, dicamba is particularly prone to vapor drifting for up to two weeks. It's hard to get a good weather forecast for the week we are in, let alone for two weeks.

[By JOHN FULTON, University of Illinois Extension, Logan County]