Helmihisporium Blight is the most common turf fungus in our area. Initial symptoms are a blue to grey color and later the turf will turn straw colored. At that point the leaf blades have died. Many factors are involved with the causes of lawn fungus, most are preventable. The number one cause of lawn fungus is lack of water. If a turf grass is receiving sufficient water it is far less likely to develop lawn fungus. One way to check if your turf is receiving enough water is by performing a water audit (see below). Most common turf species in our area need between 2-3 inches of water per week. Often watering problems can be corrected simply by adjusting or replacing sprinkler heads, increasing the amount of time the turf grass is watered. Water penetration is also an issue and your soil may be compacted thus not allowing for proper water penetration. Aeration will help alleviate compaction. Mowing frequency and height will also contribute to developing a fungus. Never remove more than 1/3 of the turf blades in one mowing, this will stress out the turf grass and repeated low mowing will lead to developing a fungus.
How to Perform a Water Audit
- To perform a water audit you will need a few items, a ruler, and several disposable pie tins.
- Place the pie tins around your turf.
- Run your irrigation system for its normal cycle.
- When the cycle has concluded, retrieve the pie plates, place them on a level surface, and measure the water inside. This will help to determine the precipitation rate for each individual zone.
- After you have measured the amount of water in a pie tin, divide that number by the time in which the system was active.
- Example: ¼ of an inch collected over a 15 minute period of time means that in 1 hour that particular zone puts out 1 inch per hour. Do this for all zones to establish precipitation rates for each zone.
- Adjust the zones accordingly to reach a unified 1 inch per hour precipitation rate in all zones. You may need to repeat the water collection procedure to insure uniformity.
Once you have established a uniform precipitation rate, it is now time to calibrate the automated timers or sprinkler clock. Using the example above, you have a precipitation rate of 1 inch of water for every hour of run time.