Management of Turfgrass Diseases

Diagnosing Turf Problems. The first step in management of turfgrass diseases is proper diagnosis. Bulletin 271 (titled Your Lawn) will help in determining the cause of lawn problems. Insects, drought, excessive water, fertilizer burn, and other factors can cause symptoms that may be confused with disease symptoms. Additional help and bulletins on specific disease and insect problems are available by contacting an extension agent in your county.

The C. Wayne Ellett Plant and Pest Diagnostic Clinic, 2021 Coffey Road, Columbus, Ohio 43210 (614-292-5006) can help with diagnosis of turf problems. The accuracy of any diagnosis depends on the information you supply, the plant material you select, and the condition in which it arrives. Collect specimens at the time the symptoms are still fresh and before fungicide treatments are made. Do not add water to the sample and, if the soil is saturated, allow to dry before sending. Samples should contain healthy and unhealthy turf. It is almost impossible to diagnose a grass sample that is nearly or entirely dead. Grass samples should be at least 4 by 4 inches and 2 inches deep, and should contain an intact layer of soil below the thatch layer. For golf course superintendents a cup cutter works well.

Rapid delivery of the sample and the turf specimen form to the clinic is essential. If the sample is to be mailed, it is best to get a Plant and Pest Diagnostic Clinic Turf specimen form (there is a specific form for turf) from your county extension agent, and fill the form out completely. The crucial questions you need to answer are: what are the symptoms and when were they first noticed? What, when, and how much fungicides, insecticides, herbicides, and fertilizers were applied? Include photograph if possible.

Wrap the turf sample securely in several layers of newspaper or aluminum foil; then pack it tightly in the mailing carton to avoid contamination of the leaves with soil particles. Fill empty spaces in the box with wadded paper or packing material. Use overnight mail services. Mail early in the week to avoid packages remaining in the post office over the weekend.

Prevention of Turf Diseases. The first line of defense against turfgrass disease is the preparation of proper soil conditions before the grass is planted. The second most important step is the proper choice of grass types, varieties, and clean seed. Bulletin 546, titled Lawn Establishment,

gives you information on these subjects. Many lawn problems are the result of poor growing site and/or poor grass selection. Genetic resistance of turfgrass plants against many diseases is available.

Correction of Turf Diseases Through Renovation. Often the best way to correct severe turf disease problems due to poor soil conditions or excessive thatch (> 1 inch) on established lawns is through renovation. Renovation is the process of killing the turf, improvement of the soil through amendment, and replanting. Disease problems due to poor varietal selection can usually be corrected by renovation with new disease resistant varieties (see Bulletin 271, titled Your Lawn).

Correction of Turf Diseases Through Maintenance Practices. Reduction of disease problems in established turf can often be accomplished by changes in cultural practices such as mowing, watering, fertilization, pruning, and core aeration. This bulletin provides information on maintenance practices for managing many common turf diseases.

Short-Term Correction of Disease Problems with Pesticides. Disease is often a problem on highly managed turfgrass. Fungicide application is generally not justified when the primary cause of decline is stress due to environmental conditions such as high temperature or water-saturated soils. Very succulent grass may provide ideal conditions for plant pathogen activity. Fungicides are often needed where there is a demand for high quality turf and weather conditions are favorable for pathogen growth. Fungicides can be essential for maintaining turf quality in such situations.

This bulletin provides information on the selection of fungicides for managing turf diseases. Granular pesticides are often more convenient for the homeowner to apply than products that are to be applied with a sprayer. However, a spray application is often a more efficient and effective means of delivering the product. When spraying fungicides, use pressure above 25 PSI (lb per square inch) to ensure good penetration and distribution of the material.

In some cases the fungicide should be applied before disease symptoms appear - this is especially true for crown and root pathogens. In addition, the fungicide must be delivered to the area of the plant where the pathogen is active. Read the label for specific information.