Originally created 05/15/98

Wet spring could mean increase in lawn fungus for homeowners



Homeowners in Augusta may face major problems with turf fungi and other lawn diseases because of the wet spring.

Three conditions must be satisfied before a disease develops in a turfgrass: A susceptible plant and disease-causing organism must be present, and favorable environmental conditions promoting disease development must exist.

Disease may be controlled by reducing plant susceptibility, controlling the pathogen or modifying the environment.

The key to disease control is having healthy plants. The following management practices will help maintain a vigorous, healthy turf and reduce turfgrass disease.

[z]n[] Prepare the soil properly at planting. Take soil samples to determine the proper lime and fertilizer requirements. Remove wooden debris from the lawn and provide good water drainage. Make sure the area is graded to prevent surface water collection.

[z]n[] Purchase high-quality, disease-free seed, sod or sprigs from a reputable dealer. If the lawn is to be seeded, use fungicide treated to discourage pre-emergence seed rot and damping off. Certified plant material is recommended but not always available. Nematodes and disease problems can be brought in on sprigs and sod. Inspect the plant material, and if problems are detected, notify the dealer.

[z]n[] Mow the grass at the recommended cutting height. Turfgrasses should be mowed often enough so that no more than [1/4] to [1/3] of the plant material is removed. If more plant material is removed, the grass will become stressed and more susceptible to disease-causing organisms. Keep mower blades sharp and collect clippings. Uncollected clippings may eventually add to the thatch, and disease-causing fungi can survive on this dead organic matter. Raise the mowing height during stress periods such as drought.

[z]n[] Follow proper watering practices. Apply water only at the first signs of wilt. Apply enough water to wet the soil 5 to 7 inches deep. If soil becomes compacted, loosen it so the water can penetrate to the proper depth. Water thoroughly in the early morning if possible. Late afternoon will encourage disease development during the night.

[z]n[] Remove excess thatch. Excess thatch reduces water infiltration, creates shallow rooted turf, and encourages insect and disease problems. If the lawn is not mowed correctly, thatch accumulation from the clippings could create a problem. Disease-causing organisms survive and multiply in this thatch material. Excess nitrogen fertilization can also cause thatch accumulation. If thatch accumulates and the lawn becomes soft and spongy, it should be dethatched in early summer by vertical mowing in two or more directions.

[z]n[] Allow for adequate penetration and air movement in shaded areas. In heavily shaded areas, excessive moisture on grass blades can be a problem. Disease-causing fungi use this moisture to survive and to infect the grass. It may be necessary to prune trees and shrubs, and design landscape plantings so that humidity is reduced by light penetration and air movement.

[z]n[] Apply fertilizers and lime at the proper rate for each type of grass. Excessive fertilization can make grasses more susceptible to disease.

Remember that good management and proper maintenance can prevent many disease problems. Where disease does occur, chemical control is slow to work and can be very expensive. Consult your extension agent or garden center for recommendations concerning fungicides and their use.

Clyde Lester is director of the University of Georgia Extension Service office in Richmond County.