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| Green & Growing (Summer 2007) |
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CSI: Cause-of-stress investigation
Detective work can help solve your lawn problems
By Bob Tracinski, master gardener
Gathering evidence using criminal
investigation techniques has become a
popular theme in top-rated TV shows.
Some of these techniques can be used
to detect the causes of stress in your
lawn. For a homeowner, CSI need not mean
Crime Scene Investigation —it can mean
Cause-of-Stress Investigation.
Read the Room.
Look around at your lawn
for signs of stress. Yellowish hue? That could
indicate an iron deficiency. Iron should be
applied as a liquid spray or in a mix with
nitrogen and sulfur. Brownish look? Could
be shredded grass tips caused by a dull
mower blade. Sharpen the blade. Dead spots?
Strange things such as mushroom rings?
Let the Victim Talk.
Now focus on one area:
Get down and look closely at the problem.
Let the dead or injured grass speak to you. Hold a
blade of grass. Curled or bluish looking? Needs watering. Discolored? Most lawn diseases are caused by a fungus: You can see yellowish
brown or powdery gray spots. Does it look thin and weak? Needs fertilizer. Could be a thatch build-up.
Get Below the Surface.
Using a garden trowel, dig out a plug of soil to observe the root system and thatch layer. The thatch should be about one-half-inch thick. If it's deeper than that, the grass tends to root in
thatch instead of soil. That's bad because
thatch harbors insects and diseases. A deep
layer of thatch indicates poor mowing practices—
mowing too short (scalping) when the
grass is too high. Mow often enough to remove
only the top one-third of the grass blades.
Follow the Evidence.
Occasional mushrooms may mean there is decaying wood under the soil — dead tree roots or perhaps
buried lumber. This is not a major problem.
However, a circle of mushrooms — called
Fairy Ring — is a problem. This is a fungus
that continues to spread as the ring grows
larger. The area of lawn just inside the ring
has become water resistant, so it's important
to aerate, use a wetting agent so the soil will
accept water, irrigate, and mow often.
History Tells a Story.
Dead spots — places where grass won't grow — need to be thought through. What happened there that could cause stress? Heavy vehicle traffic can compact soil. Running children can scuff grass.
Buried building debris such as drywall can
absorb moisture.
Bag the Evidence.
Send samples to a lab for analysis — a soil test. Use a clean tool to collect a teaspoon of soil about 2 inches below the surface from four or five locations in the problem area. Put it in a container — some labs provide a small box for this — and label it LAWN. Give it to a county Extension agent or university horticulture department and allow about four weeks for an answer. The analysis will tell you the pH level (acidity) of the soil and other information you need to take proper corrective action.
With some forensic techniques used in
crime shows, you can find the cause of stress
in your own lawn.
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