Lawn diseases are not only unsightly, but often difficult to identify. In most cases, lawn diseases are fungal, arising from any combination of unbalanced nutrients, inadequate irrigation and poor air circulation. While fungicidal sprays are beneficial, controlling and eliminating lawn diseases mostly involves promoting a dense, vigorously-growing turf. This can only be obtained with regular care and management throughout the growing season and into its dormancy.
Aerate the lawn once or twice each year to provide optimal air circulation throughout the soil. Complete the process once annually for sandy-to-moderate soils and twice a year for heavier clay loams. Begin every growing season with an aeration process just after the final spring frost. Dethatch the lawn on the same aeration schedule, removing any excessive debris to promote improved circulation.
Develop a healthy watering schedule. Irrigate the lawn in the early morning to beat the evaporation of the afternoon sun. Provide the lawn with 1.5 to 2.0 inches of water using a slow irrigation process, such as a sprinkler or drip irrigation system. Water the lawn deeply and infrequently to promote the lawn's strong, deep rooting system. Allow the lawn to near drought conditions between watering applications, watering about every seven days and adjusting for dry and rainy periods.
Feed the lawn regularly throughout the growing season. The University of California's Agriculture and Natural Resource department recommends that all lawns receive four to six pounds of nitrogen per 1,000 square feet of lawn each year. Use a well-balanced, slow-release fertilizer. Provide sandy loams with smaller, more frequent applications and heavier loams with higher-rate applications on a less-frequent schedule. Fertilize during cool days when temperatures will remain below 85 degrees F. Never feed a drought-stressed lawn.
Mow the lawn frequently to avoid the need for excessive removal. Never remove more than 1/3 of the blade during any one mowing session. Maintain a lawn height between 2.5 and 3.0 inches during the growing season. Reduce the lawn's height by approximately one inch during its dormancy period. Reduce the potential for fungal infections and cross contamination of blades by maintaining sharp mower blades and cleaning the blades after each mowing session. Collect the mowed grass from the lawn immediately after each mowing session to prevent excessive build up and potential infection.
Treat the lawn with a fungicidal and insecticidal treatment to reduce and prevent the potential for lawn diseases. Apply spray applications during the early spring and late fall. Choose applications that meet the requirements of the lawn. Follow the directions closely and never over-apply chemicals. Speak with a lawn or nursery specialist for selection assistance.