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Cornell University : Cornell Cooperative Extension
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Late Summer and Fall Lawn
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September 12, 2001 Fortunately this past summer most parts of Long Island received adequate rainfall to the point where supplemental irrigation on home lawns was not needed. This was unlike the summer of 1999 where drought conditions plagued numerous home lawns, which resulted in damage to the lawn and/or weed infestations. This required some type of renovation by the end of the summer. Chances are that renovation may not be as necessary this year since many lawns never were damaged by drought. If you did not turn off your automatic irrigation system you may have caused an over watering problem on your lawn. This could have resulted in increased disease problems. In this case you may now need to renovate your lawn. Early September to mid-September is an ideal time to renovate a lawn or start a new lawn from seed. If it is determined that the lawn needs renovation it is important to identify and correct the factor(s) that resulted in the need for renovation. If you do not correct the previous problems before renovating, chances are you will deal with these same problems in the years to come. This could include eliminating all grass and weeds and starting all over. You would want to choose grass types and varieties that will match the site and desired maintenance levels as well as choose those that resist diseases. Some grasses contain endophytes which will help control insects like chinch bugs and sod webworms. Research by turfgrass specialists at Cornell University has found that the following renovation procedure worked best in their work. After eliminating the weeds or undesirable turfgrass, scalp the lawn by mowing. Next core aerate two times one at a right angel to the other. Use a machine that removes ½ inch diameter cores that are 2 inches on center. Make sure the soil is dry enough so that the core holes will collapse-a necessity to gain the advantage of core aerating. When the cores are dry enough drag the area breaking up the cores creating a thin, even soil layer. Spread the grass seed and apply a starter fertilizer (i.e. 18-24-6). Drag the fertilizer and the seed into the soil layer created by the broken cores. Roll the are which will lightly firmteh soil and press the seed into good contact with the soil. Water the seeded area and follow up watering as necessary to keep the soil moist, but not soggy wet. Three weeks after the new grass seed has completely emerged (remember Kentucky bluegrass takes about 3 weeks to germinate) apply a regular slow-release turfgrass fertilizer. Mow the lawn at a two-inch height as soon as necessary. Do not let the grass get too tall worrying that the mower is going to damage the young grass. Late summer and fall is a good time to consider core aerating your lawn. This process can prove to be adventageous in managing soil that is compacted or thatch layers that are becoming too thick. You can follow the suggestions for aerating given above in regard to core size, direction, soil moisture, etc. Some turfgrass managers will apply a very thin layer of a quality, finished compost after aeration that gets dragged into the lawn along with the cores that are broken up. Remember that all compost products are not the same. Be sure to purchase a quality product. When it comes to fertilizing a lawn the late summer and late fall can prove to be beneficial in regard to improving your lawn. After the lawn has recovered from the summer apply the first application of fertilizer. This is usually best done in early September. Follow this up with another application in mid to late November. The key to the November application is to wait until the lawn has stopped growing shoots. This will often occur when the air temperatures have not reached 60 degrees F. for 7 to 10 days. An application of fertilizer then will help promote roots and rhizomes. In addition, nutrients are stored and available for gradual growth the following spring. Avoid applying fertilizer in October or early November when the grass is still producing high amounts of shoots. This only makes you cut the lawn more often and could make the lawn more susceptible to winter injury. It is recommended that the fertilizer you use be in a slow-release form especially for the November application. Quick release, soluble fertilizers applied during that time have the potential to leach and are not recommended for that reason. Usually temperatures are cool and rainfall is regular in the late summer and fall so routine supplemental irrigation of lawns is unnecessary. If soil moisture is adequate turn off your sprinkler system and leave it on manual until it is ready to be serviced and turned off for good. You are only wasting water if the soil is already adequately moist and you may encourage certain diseases to develop. This is true at other times of the year as well. Unnecessary irrigation is often applied during the spring when soil is moist and temperatures are still cool. Grubs (larval stage of scarab beetles) feed on turfgrass roots and this damage may start to become apparent in September and October. Unfortunately it is often too late to control these pests efficiently by this time of the year. In addition much of the damage has already occurred and applications of insecticides too late just may not make a difference. Before you treat for grubs it is recommended that you sample the lawn randomly first and count the number of grubs found per square foot. A rule of thumb is that if you find to 10 grubs per one square foot it is probably necessary to treat the lawn to prevent damage. If you find less than 8 to 10 a well-maintained lawn should be able to tolerate the damage and insecticide applications may not be necessary. Sampling a lawn for grubs should be done in late July and into early August so treatments, if necessary, can be applied at that time. At that time grubs are newly hatched from eggs laid by beetles (i.e. Japanese or Oriental beetle) and more susceptible to treatments. Also they have done minimal damage at that point. Continue to mow your lawn throughout the fall as long as it keeps on growing. Do not decrease the frequency of mowing so much that you are removing more than 1/3 of the leaf blade at any one mowing. The rule of thumb is not ever remove more that 1/3 of the leaf blade (more than 1/3) the grass plant stops growing and is in shock. It is not uncommon to be mowing lawns mid to late November on Long Island. If your lawn is healthy and growing strongly in late fall do not put that mower away too soon. Usually the need for mowing stops when the same weather conditions described above for November fertilizing are attained. The late summer and fall is always a good time to test the soil in your lawn. If found to be necessary you can apply the recommended rate of limestone any time during the late summer and fall months. Beat the spring crowds and contact Master Gardeners of CCE Yates County for instruction on how to have your soil tested for pH and/or nutrients. Cornell
Cooperative Extension Yates Association |
