Japanese Beetles and Pruning Evergreens
By John Fulton

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[June 26, 2014]  Japanese Beetle Update - The Japanese beetle emergence is underway. I caught the first beetles on June 17 in a pheromone trap north of Lincoln.

Favored plants include Japanese maple, Norway maple, Horse chestnut, Hollyhock, Flowering crabapple, 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 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.” The trend has been for a very heavy population for four or five years after you first get them, then declining numbers afterward as natural diseases and predators help control populations. Of course, last year there weren’t many at all due to the 2012 drought affecting egg laying and survival.

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 only dealing with trees through the first seven years of their life or so.

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 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 of 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.

When pruning evergreens, remember there is a “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.


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