Garden Talk - Tree problems can be a bother to some gardeners

Our largest plants, trees, anchor our landscapes and provide countless benefits, both practical and aesthetic. So we have to feel concerned when problems show up in those all-important plants.

Anyone whose tree plantings include conifers may have trouble with spruce spider mites. They do feed on all conifers but seem especially active on Colorado blue spruce, Black Hills blue spruce, dwarf Alberta spruce, and arborvitae.

Spruce spider mites are active in cool weather, but damage from spring activity may just now be apparent, especially on trees? older branches. The mites produce yellow specks on needles along with sticky webbing.

To determine whether a tree is hosting mites, hold a piece of white paper under a branch and shake the branch. Mites will appear as tiny, slow-moving specks. If there are dozens of mites on that paper, treatment is recommended.

For small trees, forcefully hosing the tree on four or five consecutive days may eliminate the problem. Another treatment option is soap or oil based insecticides. Because these work through direct contact, it is necessary to cover the tree thoroughly. Finally, miticides, which are synthetic insecticides, may be applied in fall or spring, the periods of highest mite activity.

By now we are all sadly aware of the huge threat posed by the emerald ash borer, which continues to spread through Iowa. The USDA is experimenting with a treatment in Jefferson County, which, if successful, could be used more widely. Beneficial insects that attack the emerald ash borer were recently released at a site near Fairfield. A second year of release will then be followed by two years of monitoring.

Now it?s time to discuss a disease. Sycamore anthracnose is a fungal disease that affects sycamores, maples, oaks, and ? as though they didn?t have enough problems ? ash trees. Symptoms are brown blotches on leaves, death of young buds and shoots, and leaf drop. While none of this is pretty, fortunately sycamore anthracnose does not cause serious harm.

One pest may also affect sycamore trees. If the leaves appear bleached as we move into late summer, lace bugs may be at work. However, established trees will not be seriously harmed, so no treatment is recommended.

Of course, if Henry County?s dry weather continues, the top priority for many trees, especially young ones, will be a supplemental source of water.