Issue: August 19, 2000

• Too late to spray for pine tip moth
• Globe willow with split trunk

Too late to spray for pine tip moth

I sprayed my small Ponderosa Pines in May of this year for Nantucket pine tip moth. Last year I was told that I should also spray in July, when the notice from the state agriculturalist came out, and I did. This year I didn't see a notice in July. Did I miss it? Is it too late for spraying to do any good? I do notice some pine tip moth damage on my small trees. Will this damage continue or spread if I don't spray?

Yes, it is probably too late to have maximum effectiveness in spraying for pine tip moth. In some parts of the state, you may be able to kill the young developing larvae inside the pine shoots which the larvae has already killed. The damage to be done by the moth larvae has already been done, so you will do little that benefits your tree. In most of the state, you will probably have no effect on the larvae, so you will waste money and be exposed to some rather potent chemicals (depending on which you choose to use) without doing anything to benefit the tree. It would be best to wait until spring to spray.

You didn't say where you live. The information about proper timing for pine tip moth spraying is only available in a few larger cities in New Mexico, and it is important that the timing be appropriate for your area. Areas without the notifications usually don't have Nantucket Pine Tip Moth problems, so I assume you are in Albuquerque, Santa Fe, or Las Cruces where this information is most common. In any case, I suggest you wait for the first announcement from the Cooperative Extension Service, and spray according to directions at that time. Contact your local Cooperative Extension Office to determine how the information will be disseminated so that you will not miss it.

Globe willow with split trunk

I have a globe willow that is 4 years old. It has been well-pruned and yet this last week I noticed the trunk has a large split between the two main branches. Can I repair it in some way?

There are some things you can try to repair the damage to your tree. The first is to just prune off the branch at the location of the split. Globe willows are very prone to splitting and have a tendency to try to grow two trunks. This "codominance" with two dominant stems increases the chance of splitting. By removing one of these codominant stems, you can do a lot to solve the problem. It may look bad for a while, but in a few years, new branches should cover the effects of this removal.

Another possibility is to support the splitting branch with a threaded rod. Drill holes in the trunk and the branch, or the two codominant branches, through which a large diameter threaded rod may be placed. Using large washers to protect the bark on both branches, use properly sized nuts to draw the branches together by tightening the nuts on the threaded rod. In time, the branches will graft together at the point where they are drawn together. Use of strapping or any material wrapped around the branches to draw them together can harm the tree.

A caution is in order regarding this. Years later when the tree has grown over the threaded rod, it becomes dangerous to use a chain saw to cut this tree. In cutting the tree down or cutting it into pieces after removal, the threaded rod can become very hazardous to the chain saw operator. I prefer to recommend removal of one of the splitting branches if possible.

Be aware that the split has allowed fungi and other organisms into the trunk of the tree, so there has been a lot of damage done already and the tree's life has already been shortened. Watch for signs that the tree is declining and remove and replace it if necessary.

Send your gardening questions to Yard and Garden, ATTN: Dr. Curtis Smith NMSU Cooperative Extension Service 9301 Indian School Road, NE, Suite 112 Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

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