Stress Encourages Pest Problems
Lawn grass can be stressed by the way you care for your lawn. Stressed lawns tend to be much more attractive to sod webworms than healthy lawns. Lawns needing water and lawns receiving either too much fertilizer or too little fertilizer will tend to build the stress levels and thereby make the lawn more vulnerable to a webworm. Pest insects prefer to go after weakened plants that are struggling and lack vigor for some reason. Researchers are examining the effects on insects of glutathione, a chemical produced by stressed plants, and they have found that glutathione is actually beneficial for certain harmful insects - it aids their reproduction, growth, and may even bolster their ability to resist pesticides.
Some Causes Of Plant Stress
After you deal with the immediate sod webworm problem, try to figure out what might be causing your grass to be vulnerable to pest attack. Some causes of plant stress include:
Excessive use of nitrogen-rich fertilizer, which encourages too much leafy plant growth--perfect webworm food!
Use of pesticides against other pests which also kills off the webworm’s natural predators and parasites
A thick thatch layer, which prevents water from entering the soil and provides ideal webworm habitat
A temporary springtime superabundance of webworms that later levels off when natural enemies catch up
In the end, you may never figure out what caused the plant’s stress, but it’s always good to think about it when sod webworms appear. If you eliminate the underlying causes of stress in the grass plants, the webworms may be less likely to return.