Lawn webs? - Knowledgebase Question

Sycamore, Il
Question by artandnancy
September 12, 2008
We have what looks like webs on our lawn and also on our evergreens. They are just small patches but we are concerned that they will do damage. What are these and what can we do to get rid of them and to prevent more from forming?


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Answer from NGA
September 12, 2008

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I think you're dealing with two different problems. Evergreens are susceptible to a pest called spider mite which leaves tell-tale webbing between the needles and the stems of evergreens. They prefer dry, dusty conditions such as are found in the center of an evergreen tree or shrub. The best control is to hose your evergreens off periodically during the summer months. This will wash off the dust and also discourage the spider mites.

As for your lawn, it is very difficult to diagnose a disease with the limited information given but what you describe could be one of two summer diseases that look similar but occur under very different maintenance systems.

The most common disease is dollar spot that tends to affect Kentucky bluegrass and/or perennial ryegrass lawns that are somewhat low in nitrogen. Though the exact amount of nitrogen needs of a lawn varies with soil type, if it is irrigated or not and so on. Generally for lawns, we recommend between 2 and 4 lbs of actual nitrogen/1000 sq ft. If you apply 2-3 lbs or less of nitrogen per year, there is a very good chance it is dollar spot. The most effective control for dollar spot is to apply slightly more N over the course of the year with most of it in the fall. This disease is also common on lawns where the clippings are bagged which robs nitrogen from the lawn.

The other disease could be pythium which attacks mostly perennial ryegrass lawns that receive ample nitrogen and may actually be too green and succulent for this time of the year. If you apply 4 lbs of nitrogen or more/1000 sq ft, you may be dealing with pythium. The most effective control for this is to reduce the amount of nitrogen that you apply over the course of the year.

Hope this informtion is helpful!

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