County Extension Agent

This spring has been a little unusual in terms of lawn disease. The fall season is usually what brings rainy, humid, and cool conditions which are favorable to many lawn diseases-especially brown patch. However, this spring I have had many calls and seen several cases of Brown Patch. The rain has been a blessing, but added with the cool, cloudy days and heavy dew each morning it has created the perfect environment. This disease decreases overall turf quality and can be quite stressful to your grass. Most turf species are susceptible, especially St. Augustinegrass, zoysiagrass, and centipedegrass.

Brown patch develops rapidly when day-time air temperatures are between 75 and 85 degrees Fahrenheit and affects leaves, stems, and crowns. Turfgrasses affected by brown patch normally exhibit circular to irregular shaped patches of light brown, blighted, and thinned turf. Yellowing of the leaves is not uncommon, especially at the edges of the patch. Inside the infected area, the turfgrass may remain green which leaves a “frog-eye” appearance. Leaf sheaths in the infected site also become rotted and water-soaked to the point that a gentle tug of the leaf blade easily separates it from the runner. To prevent this disease from attacking your lawn, pay close attention to your watering habits, thatch accumulation, and your nutrient management program. Several fungicides can also be used for the prevention and control of brown patch. Those include Turfcide 10 G (PCNB), Ortho Lawn Disease Control (propiconazole), Sprectracide Immunox (myclobutanil), Ferti-lome Systemic Fungicide (propiconazole), Hi-Yield Lawn Fungicide Granules (PCNB), Green Light Fung-Away Systemic Granules (thiophanate-methyl), Green Light Systemic Fungicide (triadimefon), and Dragon Systemic Fungicide 3336WP (thiophanate-methyl).

For more detailed information on “Brown Patch” and recommended fungicides, go to the Aggie-Turf web site at . Click on “Answers 4 You”, then “Diseases”.

In addition to the use of fungicides, proper watering of the home lawn is one of the most important practices you can follow to prevent disease. With the help of our Texas AgriLife Extension Turfgrass specialist, I have put together this list of most frequently asked questions on watering the home lawn. I hope you find it useful in helping keep your lawn healthy, while conserving water.

How often should I water my turfgrass?

There is no “set” period between one watering and the next for all of Texas. It will depend on your location, rainfall, and time of year, the lawn grass, how much water you can apply in one watering and how well your soil takes in the water and holds on to water so the lawn can use what is applied. The key is to learn how your lawn shows sign of moisture stress. Turfgrasses can endure some extended moisture stress and “bounce back” when you water at the right time.

What is a good indicator that my lawn needs watering?

Signs of moisture stress (leaf rolling, off color appearance) are good indicators of the lawn needing water. Yet the whole lawn may not show those symptoms. Lawn areas that show signs of moisture stress first can be your “indicator areas”. Hand-water these spots as opposed to watering the entire lawn. This can help conserve water by not watering lawn areas that do not need it. Always try to recall the last rainfall or irrigation and look at the weather forecasts to see if you can wait for “Mother Nature” to help the cause with some rain showers. You might be able to hold off on watering before it is needed. You can also use tools (spade, soil probe, screwdriver, etc.) to check the moisture in the soil profile prior to irrigation.

How much water does my lawn need?

If your lawn is never allowed to show any signs of moisture stress then you are probably watering too much. Lawn grasses use the most water in summer, and less during late autumn, winter and early spring. In the absence of rain, lawns can use between 1 to 1.5 inches of water per week in the hottest summer months. But again this depends on conditions. Need also depends on grass species & soil type.

When should I water my lawn?

Water your lawn in early morning and take advantage of less wind and reduced evaporation so water can be applied uniformly and move into soil.

Water tends to runoff my lawn while watering - Why?

Runoff happens when irrigation is applied at a rate that exceeds that amount of water that can infiltrate into the soil. This can be caused by unchecked heavy irrigation or watering too long and the soil then cannot accept any more water. To stop runoff, know how long you can water before water runs off each lawn area and make certain not to exceed that length of time.

How do I determine “inches of water” per watering?

Inches of water applied from irrigation can be easily measured by using flat-bottomed catch cans evenly spaced between sprinkler heads or around a sprinkler operating off a garden hose. Water for 15 or 30 minutes and measure the water caught in each catch can using a ruler. Once measured, that is the amount of water applied per unit of time in inches. It is useful to know how long the sprinklers must run to put out 1 inch of water or how much water can be applied before runoff.

How deep should the moisture be for adequate turf irrigation?

Root growth benefits when irrigation water wets the soil to the depth of the root system or just beyond. This may be difficult to accomplish in heavy soils and may require repeat watering cycles. The recommendation is to water as deeply and infrequently as the soil allows.