Question
We have a elm tree that has wasps or bees swarming around it. It is quite high up so we can't see what is attracting them. The leaves are all falling off the tree, so we think it is infested with some kind of pest that the wasps are feeding off of. What can we do to remove this problem? The tree is very tall and we're thinking of removing it.

Answer
This sounds like either slime flux or alcoholic flux.
The oozing is called "slime flux" and is caused by a bacterial infection inside the trunk. There are actually two types of slime flux: 揳lcoholic?and 揳cidic? The acidic flux smells like vinegar.

The infection can be in a wound on the trunk surface or it can be deeper inside the trunk. In either case, bacteria ferment the tree's sap; it seeps out and down to the ground. Sweet-eating insects (wasps, bees, yellow jackets) would obviously be attracted to the damaged area.

Alcoholic or white flux also called frothy flux, is not related to wet wood. It occurs where microorganisms ferment sap in cracks and other wounds in the bark and cambial region. Alcoholic flux is acidic and nearly colorless, and sometimes appears as a white froth. It often emits a pleasant fermentative odor, and persists only a short time in summer. The associated microorganisms apparently produce gas and alcohol. Alcoholic flux is reportedly common on stressed trees, notably on Liquidambar stryaciflua (sweet gum), Quercus (oak), and Ulmus (elm) in the Midwest and Salix (willow) in the Southwest.

Alcoholic flux is stress related. In this case, heat stress mostly likely set the stage for this problem. To help avoid this problem, good cultural practices should be maintained. Proper watering during the growing season as well as during the winter months is critical. Since this tree is in a lawn, care must be taken to avoid over watering and other damage such as caused by lawn mowers and string trimmers.



There is no treatment for the condition. The best thing to do is to wash off the trunk to discourage bugs. Mix a pint of chlorine bleach in a gallon of water to make a final rinse. The flow of sap is periodic; it may disappear and not reoccur or you may see it every year.