Question
Hi,

We have a large more than 20yrs old oak tree.  This year we noticed gall mites on the leaves.  Almost every leaf is covered with them. As a result, there is a sugary substance that falls off the tree on our vehicles and driveway, which is very sticky but comes off with water.  What is the best way to get rid of these mites?

Thanks

Answer
These insect suck the plant juices and secrete a sugary substance called honeydew. Treat the tree with an insecticide called Bayer Advanced Tree and Shrub Insect control. This is applied to the soil around the tree and the roots will transport it to the leaves and twigs and when the insects feed they are killed. It will take a couple of weeks to see the results after it is applied. Here is a web link to information on this product--you should be able to get it at your local nursery.
http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html