Check sprinkler pattern during hot, dry conditions


Now that another typical East Texas summer has probably turned your yard into straw, your sprinklers are probably running in an attempt to keep plants – and turf – alive.

Hot and dry conditions put a lot of stress on a lawn, which can be seen in sick or dying patches.

In many cases, these are lawns with irrigation systems that are being run regularly, so folks usually assume it is something other than a lack of water, like chinch bugs or a disease.

Many times, however, lack of water is exactly the problem. The sprinkler system is just not reaching certain areas of the lawn, resulting in stressed grass among the green.

Timely watering will help maintain a quality lawn. How much and how often you water depends on your soil type, and the amount of shade the lawn receives.

Sandy, porous soils require more frequent watering; clay soil retains moisture longer as do sections of lawns receiving more shade.

Lawns need about 3/4 to 1 1/2 inch of water per week (again, depending on soil type, etc) to maintain peak performance. The best watering scheme is to help the grass develop a deep root system that can take advantage of a larger reservoir of water by watering deeply and as infrequently as possible.

That may mean watering every 3 to 7 days in the summer, depending on soil type, temperature, rainfall, etc.

Although you should water as infrequently as possible, you should also water at the first sign of wilting grass. Ideally, your irrigation scheme should wet the soil 4 to 6 inches deep.

This may be difficult on clay soils or on sloping sites. Do not waste water by allowing runoff to occur. In these cases, either turn the sprinkler off or move the sprinkler to a new location to allow the water to soak into the soil.

Then move the sprinkler back and apply more water to further wet the root zone. You can determine the depth of water penetration by pushing a garden spade or sharp probe into the soil.

The probe will move into the soil very easily where it is moist. The probe becomes harder to push when it hits dry soil.

Remember those dry patches we were talking about? There is an easy way to easily determine if lack of water is the problem. Take a shovel and dig into the soil and feel the soil the day after you’ve watered.

Grab a small handful of soil and squeeze it into a ball. If there is adequate moisture the soil will remain as a ball and you can feel the moisture. Soil from dry areas will be powdery and will not hold together as a ball. Often the soil will appear lighter in color, but don’t rely on that indicator alone. Then, do the same test in a green, healthy area nearby and compare your results.

If you have a sprinkler system, you can check the distribution pattern of your sprinkler heads by setting out a series of small catch cans, like tuna or cat food cans, to collect the water while running the system.

Compare the amounts collected from the green areas and the dry areas. If the amounts are significantly different, then your irrigation system needs checking out. Sprinkler heads may be misaligned or plugged. Often small particles lodge in the heads cutting down on the total amount of water released. So the heads appear to be working but less water is coming out. Low water pressure may cause the spray pattern to not completely reach all the grass resulting in dry patches.

If you discover lack of water is the problem, don’t just run your sprinkler system longer if the rest of the yard is getting adequate water – that would be wasteful. Simply supplement with a hose- end sprinkler in the dry areas until the irrigation system can be adjusted or serviced.

St. Augustine could have another culprit causing dry or dying areas during the summer time – chinch bugs. Chinch bugs typically strike first in the hotter parts of the yard, like near a driveway, the street or sidewalk.

Early symptoms of chinch bugs include stunted growth, wilting, and then yellowing. Finally, the grass dies in irregular patches. One tipoff is if the grass is wilting and supplemental irrigation doesn’t correct the problem.

Adult chinch bugs are black, about 3/16 inch long, and have either fully developed or very short wings which, when held in place across the back appear as white spots. Immature chinch bugs range from 1/16 to 3/16 inch long and are either dark grey or orange-pink and have a white band across their abdomens.

Check suspected areas for chinch bugs by carefully observing the outer edge of affected patches of grass for the rapid movements of these small insects. In large infestations, you can often see them quickly darting back and forth, up and down on the blades of grass.

One way to drive them out of the thatch so they can be more easily seen is to flood the area with water where damaged and healthy grass meet. Some folks cut the bottom from a coffee can, force it into the soil and fill it with water. Chinch bugs, if present, will float to the top. Soapy or sudsy water is another way of forcing them up out of the thatch.

Check several areas to be sure. If found, then treat the spot and surrounding area with an insecticide labeled for chinch bugs (there are many). Treatment may be more successful if the grass is wetted a few hours before treatment. Read label instructions for specific instructions, and dispose of pesticides properly.

--East Texas Master Gardeners


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