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If you have Japanese beetles, you may want to do something; they'll be back

Japanese beetle update, evergreen pruning and yellow grass

By John Fulton          Send a link to a friend

[July 02, 2007]  The numbers of adults have been impressive in some cases. Trees, shrubs, vegetable plants, and fruit plants and trees have all been affected. Of course there are some plants that are favored feeding sites. These would include Japanese maple, Norway maple, horse-chestnut, hollyhock, flowering crab apple, apple, cherry, peach, rose, mountain ash, linden and grape. There are other plants that are seldom attacked, such as red maple, silver maple, boxwood, flowering dogwood, euonymus, ash, oak and lilac. Of course, you need to take this list with a grain of salt, since I have sprayed large numbers of beetles on the seldom-attacked plants this weekend.

My rule of thumb is to protect fruits, vegetables, valuable ornamentals and new transplants. Most are spraying Orthene, Sevin, permethrin or bifenthrin. The frequency is what gets us sometimes, with sprays needed at least every week in most cases. To dispel a common myth, once you have the beetles you will always have them. They do not occur on an infrequent basis like periodical cicadas, nor is it "just a year to have them." They have expanded their range, and you are now in it.

Pruning evergreens

This is the time of year to wrap up pruning chores on evergreens. This includes both needle-type and broadleaf evergreens. If you're wondering what a broadleaf evergreen is, that includes holly, rhododendron and azalea. The logic behind pruning your yews at this time is to allow sufficient time for regrowth to become hardened off before winter and to keep new growth from becoming too rank before the winter months.

Pruning evergreens is part art and part science, but mostly art. A few simple rules to follow make the job results much more pleasing. Upright growing evergreens, such as pines and spruces, should not have the main leader cut off. This will destroy the natural shape and will make the resulting growth more susceptible to breaking off. If individual branches are being cut off, they should be cut back to a bud. This will allow the bud to become the new main branch. You can also control growth direction of branches in this way. If you are growing trees for cut Christmas trees, all bets are off, as you are dealing with trees only through the first seven years of their life or so.

Make sure you use the proper equipment. Individual pruning cuts are best done with bypass loppers or pruning shears. These make clean cuts without much damage to the remaining wood. The old anvil-type shears and loppers cut to a point, then crush the remaining wood. For yews, junipers and arborvitae that are trained to a certain size or shape, you will want to use hedge shears (electric or manual) that are sharp and properly tightened. Most of these types of shears can cut up to about a quarter of an inch in size.

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When pruning evergreens, remember the dead zone. This is the area toward the center of the plant that doesn't receive much light. It also has few needles or active buds. Cutting into the dead zone will cause many years (or forever) of little green growth. Also, remember to prune so that the base of plants is wider that the top. This allows sunlight to hit the bottom area as well and keeps the bottom from dieing up.

Yellow grass

There seem to be many yellow patches of grass showing up in area lawns. Large amounts of rain could have pushed nitrogen below the level where grass roots can reach it, or the rain can lead to denitrification, when the bacteria in the soil break down nitrate forms of nitrogen for the oxygen they contain. Any root damage also reduces the amount of nitrogen and other elements that can be taken up into plants. Grubs of any sort, including Japanese beetle larvae, feed on plant roots. Add to this the fact that many of the yellow spots are in the area of tree roots. Trees compete for the same moisture and nutrients as grass areas, and trees are more efficient at getting these nutrients.

The long and short of it is that yellow grass areas are probably going to be with us for most of the season. Adding additional nitrogen now is not recommended unless you are on a frequent watering schedule. Even then, you probably won't green it up any time soon. The yellow is not that efficient a pigment for making food, so those areas will be a little less healthy than others. Try to mow at recommended heights of 2 to 2.5 inches, fertilize in early September and water at least a quarter of an inch per month if things stay dry for a month.

[Text from file received from John Fulton, University of Illinois Extension, Logan County Unit]

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