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Hortiscope: Spruce trees will survive bugs and high winds

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News Park Rapids,Minnesota 56470
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Hortiscope: Spruce trees will survive bugs and high winds
Park Rapids Minnesota PO Box 111 56470

Q: I have four small spruce trees. Last year, worms started eating the needles. I used several sprays from the store, but to no avail. Then I started killing them with my fingers. There was no end to them. This year, the needles have not returned, but there is new growth on them. If the worms return, what should I use to get rid of them?


A: Sevin is what you should use because it will kill them on the spot! Those worms are sawfly larvae that have the appetite of a high school football team.

Q: We have eight blue spruce trees. Two of them are dying, but I'm trying to save them. We live in an area that has been getting a lot of high wind. One tree wasn't affected because we had it tied well, but it is dying anyway. We had a landscaper put down mulch in the fall, but I feel it was too much. I pulled back the mulch and got rid of some of it. I also fertilized the tree.

The other tree was affected by the wind, so it is bent over. Should we take it out and replant it? How much mulch and how close to the base should it be? Also, how do I know if the tree is dead? Our soil is like clay, so I used composted manure and peat moss. Thanks for your help because I'm new to gardening.

A: Blue spruce is tolerant of winds without any input from humans, so I wonder where it is you have them planted and how they were planted. Many people, even professionals, make mistakes.

One is planting too deeply. The top of the crown where the trunk transitions into the roots should be no deeper than at ground level. Don't apply fertilizer at the time of planting. Some people overwater the planting. Keep it moist, but not soggy.

As you assumed, some people use too much mulch around the tree. The mulch should be organic material, not rock. The mulch should not be up against the trunk of the tree. Keep the mulch 3-plus inches away from the trunk. An evergreen can have green needles but be dead. Think of "live" Christmas trees as an example.

Q: I transplanted a 2-year-old red Japanese maple tree about three weeks ago. I watered it every day for about 15 minutes, but the leaves all withered. What do you think?

A: That is typical transplant shock, which is about the same as open-heart surgery on humans. If the patient (tree) survives, it will releaf a little this year. Otherwise, it is finished. Trees, such as the Japanese maple, should be planted in the early spring before the buds break out. Stop watering it every day. The roots need air along with water.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail