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Trees, trees, trees: roots recurring, rabbits nibbling needles

Q: I have a green ash tree that has roots that seem to be taking over my yard. If I have it cut down, how can I be guaranteed that all of the roots will be destroyed?

A: I can assure you that you will not destroy all of the roots. Only the flare roots around the base of the tree will be destroyed. The long lateral roots will remain and continue to sprout. To control this sprouting, treat the roots as you would any broad-leafed weed with an appropriate herbicide, such as Trimec or any similar product available on the market.

Q: We planted a limber pine extra blue in 2007. Unfortunately, we noticed that during the winter, a rabbit (or other pests) ate the needles off the lower part of the tree, but the branches are still there. Will the branches produce more needles? We also have noticed that these pests have eaten some of our lilacs. Will they survive?

A: The bare branches will not produce more needles. Sorry! As for the other plants, it all depends on what you mean by eaten. Girdling or eaten from the top down to the snow line? If the former, the plants may be doomed. If it is the latter, they will come back. I'd suggest waiting until buds break this spring to see what, if any, growth you get. This fall, I would suggest that you get a varmint repellent product. Apply it before and during the winter months.

Q: My heritage birch tree received a little fire damage to its bark up one of the three main trunks. The damage was mostly on the loose, curling exterior portion of the bark. I don't think there was damage to the main bark. The tree's exposure to the fire was less than two minutes. Parts of the trunk have turned dark, with a sort of mix of surface ash and nonburned loose bark. Will it live? Will it recover?

A: I would like to believe it will recover, but not without scarring. Wait to see what new growth there is this spring.

Q: A few years ago, I bought some Himalayan birch seeds and planted them. As I understand it, this type of birch should have white bark. However, the trees these seeds produced have a brown bark. Do you know if the white bark develops through time or is there something wrong?

A: You probably have nothing to worry about because many white bark birches have juvenile bark that is tan. As it matures, the bark turns a nice, chalky white. Be patient and see what develops. The Himalayan birch is a beauty, but not that common in landscapes.

Q: I heard that some trees grown from seed may not have the same characteristics of the parent tree, so I am worried. One of the trees I grew from seed is now about 8 feet tall, but still brown. Do you think this is normal?

A: While seedling variation does exist, unless there were other species of birch planted nearby, the variation would be minimal. You tree still is considered a juvenile, so the brown color is normal. It should start to whiten for you in a few more years.

Q: I have two flowering crabapple trees in my yard. I hit one of the trunks with the weed-eater and knocked some of the bark off. Will the tree die because of this? What should I do about it?

A: Put a ring of mulch around the trunk of the trees to keep you from nicking it with the string trimmer. The tree will recover on its own if it is vigorous enough. Other than cutting off any loose bark back to where it is attached, do nothing else.

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