The DeKalb Extension Garden Patch: All About Trees

My large oak tree has lots of sprouts or suckers developing. Why is this happening and what should I do?

Sometimes these new shoots develop when a tree is very stressed and its top is beginning to die back. However, if the top still looks good, with nice, dense, normal-sized leaves, maybe it’s because you removed other trees nearby? If you open up an area and thin out trees, the increase in light on tree trunks can also encourage the formation of new branches. Dependent upon your situation, consider pruning off all or some of these new shoots (often referred to as water sprouts or suckers). Be sure you cut them off well just behind the bark ridge and branch collar areas.  -  Gary Peiffer, DeKalb County Extension Horticulture Agent

My large chestnut oak is oozing a smelly, acidic solution out of a trunk wound. This solution is also attracting bees and other critters. Should I worry and what can I do?

This is probably Slime Flux. Bacteria get into trees through old wounds or dying roots etc. and as they grow and multiply they cause a build-up of gas and fluids in the tree trunk. Eventually this fermenting material begins to foam out from various locations on the trunk and root flares, and this usually happens in about June or Juuly. This oozing does not kill trees but it is very acidic so it is a good idea to take the time to scrub it off using a wet sponge soaked with a 10-20 percent Clorox solution. Once you are done scrubbing, hose it all off to really clean up the area. Healthy trees will close and seal these wounds fairly rapidly. If left on the bark, this constant oozing can cause surface decay, bark loss and even damage to the cambium, the growth layer under the bark. The best thing a homeowner can do other than wash the stuff off is to try to improve the tree’s vigor. You can reduce tree stress by mulching the root area and by supplying supplemental water during periods of extreme drought.  -  Gary Peiffer

My large old oak tree has a large hollow. Can I just fill it with concrete to make it safer?

No, that would not solve your problem. All it would do is cause faster decay behind it and it would make it a lot harder to cut the tree down when it dies. The best thing you can do for a wound or hollow like that is to keep it dry so it rots out slower and keep it covered with a hardware cloth screen to keep critters out of it.  -  Gary Peiffer

Can you tell me what is wrong with a couple of my apple trees? They have black leaves and dead ends on many of the branches.

Your apple trees have fire blight. This disease is caused by bacteria rather than fungi, so fungicides do not control it. Your best bet now is to use a pole pruner to remove the affected black twigs. This will be a two-person job because the blades of the pruner must be disinfected between each pruning cut. Make your cuts 12 to 18 inches below any sign of infected tissue. A simple disinfectant can be mixed by using 1 part household bleach to 9 parts water. Once mixed, pour it into an inexpensive spray bottle so it is easy to apply to the cutting blades. As you prune off branches lower the pruner so your partner can disinfect the blades with the prepared spray.  -  Gary Peiffer

If you have questions you would like answered, please email abonsall@dekalbcountyga.gov. We will answer some in this column, and the Master Gardeners on duty will reply to the others.