Q.
I live in Henderson where we enjoy having a lawn as part of our yard. It was
thick and beautiful when we moved in, but it soon withered after we made some
changes to sprinkler layouts and had the water off for awhile. I laid fresh sod
and it too struggled. I tried a fungicide and that seemed to help but it then
died completely. Now the rest of the
lawn is headed in the same direction. I’m at the point of desperation and could
use some sound advice in the midst of some differing opinions.
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| This is the lawn the reader talked about. It is dying in patches. The reader asked me to look at it (consult) but I think the disease problems we had (high humidity) earlier had a lot to do with it. |
A.
Outside of watering, some lawns experienced disease problems earlier in the
season that lingered after we had high humidity due to the rain. That change in
our weather encouraged plant diseases to occur. In the desert, it’s usually the
higher humidity that’s the problem.
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| I will take a look at this lawn and see if the disease is advancing or has stayed put. That will tell me what his options are. Now he must stop the lawn disease (if advancing) and get the grass to come back. |
The humidity is now below 15% (except directly
above lawns) and lawns should not need a fungicide application to keep the
disease from spreading if we allow the lawn to dry after we apply water, and it
is in good health. When there was higher humidity, some lawns along with some
other plants, may have needed a fungicide. A lot of it had to do with the lawns
current health.
If you applied a lawn fungicide, it should
have stopped needing the applications if the general humidity was above let’s
say 25%. Plant disease susceptibility is sometimes compared to a three-legged
stool. Plants are susceptible to fungal disease if: 1. the disease organism is
present, 2. general health and susceptibility of the plant is good, and 3. the
current weather. In this case, all diseases like moisture. A couple of months
ago the weather (humidity) was the problem. The higher humidity is now over. The
relative humidity is now in the “desert” range. I think you are seeing old lawn
disease damage (unless the lawn grasses are in poor health).
Make sure you follow label directions when
you apply any fungicide. Any traditional broad-spectrum fungicide should work,
but generally the higher-priced fungicides for lawns are usually a better
choice in that respect.
This fall we should be watering lawns
about two to three times each week. No more than four times each week for sure!
Water early in the morning (imperative) and wet the lawns from 8 to 10 inches
deep in a single application when you water. Sloped areas, or hard soils, may
need multiple starts, about 30 minutes to one hour apart, to keep the water
from “puddling” into low spots.
Your lawn may not need it but try “aerifying”
your lawn with a gasoline driven core aerifier. Then “topdress” your lawn with
a rich compost to fill the aerification holes. Irrigate your lawn immediately
after this. This process of filling the aerification holes, followed by
topdressing and irrigation, improves the rooting depth of the grass. This will
improve a lawns (grass) health.