Q:I am having trouble with cobwebs on my container evergreens. I think they are spruce. They are always covered with these webs, and I have lost several of the plants. They turn brown, and the needles drop off, and they die. Is there something I can spray to get rid of this problem?

Answer: I would guess your plants are Dwarf Alberta spruce, which are often used in containers. Unfortunately, spider mites are a terrible problem on these plants. They leave the webs you've described. These mites are microscopic, and they feed under the needles and along the stems. According to the pest Management Guide from the Cooperative Extension, you can treat them with Orthene, Kelthane or Pentac. A good garden center should have one or more of these products. The bad news is, the mites will probably return. I've never seen Dwarf Alberta spruce that didn't have a problem with spider mites. If you have to replace them one day, try something else.

. . .

Q:I have a heavily wooded lot with many huge pine trees. We have lived here for 30 years and have never seen this. In late June, I noticed a bright, white hard material about 5 inches up around the bottom of this 90-foot-tall pine tree. A few days later, the same material was at the base of four other pine trees as well as a patch here and there up the tree. I have maple and oaks in the same area, and they do not appear to have any of this white material. Do you know what it is and what I can do about it?

 

Answer: The white material you've described sounds like the material that bleeds from trees when they are attacked by the Southern pine beetle. The beetles bore into the trunk, usually near the base, first. This white material bleeds from the holes and hardens as air hits it. Since this is a borer that only attacks pines, that might explain why you don't see the material on your oaks and maples. These insects usually start on pines that have been weakened for one reason or another. However, once they kill a tree, they can no longer feed on it, so they move out in search of other pines. Because your lot is heavily wooded, have a certified arborist examine these trees for you.

. . .

Q:I want to construct a raised-bed vegetable garden in my backyard. I would like to use pressure-treated wood for the frame, but I am concerned with the chemicals in that wood. I have read that the newer pressure-treated wood has copper in it. Would it be OK to use the treated wood? I also have considered covering it with black plastic to keep the chemical from leaching into the soil.

 

Answer: There is still some debate about the use of pressure-treated wood in vegetable gardens. I have seen research that shows leaching of toxins from the wood treatment is not a problem. The amount of leaching was negligible, and what did leach didn't appear to be taken up in the parts of vegetables that we eat. However, there are still those who question the long-range effects.

Obviously, it's easy to attach black plastic to the insides and bottom of your timbers during construction. If this gives you some piece of mind, it would be simple to do it from the beginning.