Folks are starting to inquire about sick or dying patches in their lawns. On almost any
block you can find lawns with patches of grass showing obvious signs of stress. 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.
