After a slow spring, lawns are finally starting to come to life. While recent rain has been a welcome sight, you may still be finding brown spots in your lawn. These spots can be attributed to a wide range of factors and correct diagnosis of the problem is important in order to recommend a treatment. The first thing you will need to consider is the past history of the lawn. Was there a disease problem last year? Was the lawn dormant for a long period of time last summer? Have there been any activities on the lawn that could cause a problem? This article will discuss a few of the problems we are seeing this spring and what can be done to fix them.
- One thing we are seeing this spring is the effect of snow mold. Symptoms of this disease are usually seen after the snow melts in the spring. Patches of light, yellow or grayish-brown turf may be present in high traffic areas or in areas where deep snow was present most of the winter. Affected areas are often matted and may have a cottony growth present. As the grass dries, the leaves become brittle and encrust over the patch. Usually only the leaves are killed and the plant crowns are still alive. However, severe infections may kill areas of turf.
By this time of year, the damage from snow mold has already been done and all we can do is repair the damage. Rake or brush matted areas before applying water and fertilizer to facilitate faster plant recovery. If the spots do not recover, reseeding will be necessary. To prevent the problem in the future, avoid lush, green growth going into winter. Do not fertilize after September and continue to mow the lawn in the fall so that snow does not fall on a tall turf. Avoid excess thatch and prevent compaction of snow by vehicles, humans and animals.
- We have received samples of weed patches in the Plant Disease Clinic. Because the spring has been so cool, the warm season weeds such as crabgrass and nimblewill have not greened up as quickly and weedy patches in the lawn may still be brown. Treat these areas with an appropriately labeled herbicide. Be sure to follow instructions on the label for application rates and timing.
- If the brown spots are along the driveway, sidewalk or street, the problem might be salt damage. Usually, heavy watering will help dilute the salt concentrations to less toxic levels. Reseeding may be necessary if the grass does not recover.
- If you have pets, especially house pets, they may be contributing to your brown lawn. When you let them out, pay attention to where they go to relieve themselves. Often during winter months, house pets will use the same tree, corner or "spot" as a bathroom. In the spring, injured grass may be brown or straw-colored. These spots are usually bordered by a ring of lush, green grass in the spring. Heavy watering will help these areas recover.
- A final consideration is the possibility of winter injury or winter kill. Cultural practices and lawn history need to be considered. If the lawn was started from sod, it may not have established in some spots and these spots winter killed. Winter kill may also be a problem if an excessive thatch layer is present. Core aerification will be needed to reduce thatch effectively. Disease and insect problems the previous year may have weakened the turf and predisposed it to winter kill. Winter injury is also more evident when the lawn is not allowed to harden off before cold weather. If brown areas do not respond to water and fertilizer, reseeding may be necessary.
As always, if you have questions about the brown spots in your lawn, extension personnel will be happy to answer you questions. Turf samples may be sent to the Plant Disease Clinic, 323 Bessey Hall for diagnosis. Include affected areas as well as healthy turf. Pictures of affected areas are very helpful.
This article originally appeared in the May 3, 1996 issue, p. 67.