July 15, 2004

Summer brings a host of interesting problems. Here are a few that we are hearing about in the Extension office now.

What can I do about these webs in my trees? To be brief, I would suggest that you do nothing. Let me explain.

Generally, two insects make webs in trees. The Eastern tent caterpillar makes webs on the ends of the branches. The fall webworm makes their webs in the forks of the branches. These caterpillars feed on the leaves. Although this hurts the tree some, it should recover. 

I would not worry about insects feeding on trees unless almost all the leaves were gone. Healthy trees can usually withstand the loss of all their leaves and still live. This is true of most deciduous trees (trees that lose their leaves in the fall) but not pines, cedars, junipers and other conifers.

Even if we want to control the caterpillars, we must spray the entire tree, perhaps more than once. We also need to find some way to get the insecticide inside the webs to kill the Eastern tent caterpillar. For all these reasons I say, just live with these worms a while. They will eventually go away.

Some people cut the branches off or burn out these webs. This may damage the tree more than the worms would. I recommend that you do not do this.

I do not recommend spraying trees in most cases. There are almost no pests that we need to spray trees for. Think about it. Your tree has lived for years with this pest. A single spray will not protect your tree for long. The cost of spraying the tree usually far exceeds the value of this spray.

My St. Augustine lawn is getting thin and looks like it is dying out. St. Augustine is a good lawn grass, but it is disposed to disease. Wet weather following the mild drought earlier may have made the possibility of lawn disease even greater.

Grey leaf spot attacks St. Augustine lawns causing oblong straw-colored spots with purple to brown borders.  Attacked leaves can die.  The lawn can begin to die and get thin. Brown patch disease creates a slowly enlarging weak or dying spot in the lawn.  The spot may have a gray border. Brown patch can attack other lawns as well as St. Augustine.

Proper management is the best way to control lawn diseases. Soil test and lime if necessary and provide plenty of potassium. Low soil pH can make St. Augustine susceptible to disease. Use the least nitrogen you can and still have attractive turf. Use slow release fertilizers on St. Augustine.  Do not fertilize diseased lawns until you cure the disease.

Water only when the soil begins to turn dry. The grass will turn gray and the leaves will roll up slightly when the lawn needs water. Water the lawn deeply, applying one-half to three-quarter inch each time. How long will this take? Put a pie pan under the sprinkler system, turn the system on and time how long it takes to put out this much. Water this long each time. Wait until the lawn dries to water again. Water between 10:00 p.m. and 10:00 a.m.   

Check the lawn for soil compaction and thatch problems and correct if necessary.  You can spray fungicides to slow disease spread while you correct problems that are contributing to the disease problems. Read and follow all label directions.

To see which fungicide is best for your problem, you must diagnose your disease.  Call your local Extension Office for help.  We are not able to go see every lawn, but you can bring us a sample of the affected turf. Take a sample at least the size of your hand.  Take the sample at the edge of the dying spot.  The sample must contain both living and dead grass.  We need to see the grass that is currently in the process of dying. 

Proper turf culture is the best disease prevention.  Spraying alone will not cure many problems.  Use preventive lawn medicine to keep from having these lawn diseases.   Following these tips will not prevent all diseases.  These practices may lessen disease severity and make diseases less likely to occur.