Q:  I looked at a nice old mountain ash the other day. The homeowner says it was planted about 1970. What is the life span of a typical mountain ash? There are some leaves yellowing, browning and falling off but not a high percentage. The yellow leaves didn't appear to have iron chlorosis symptoms. A lot of the berries seem to be drying up and many have fallen off. I didn't see any symptoms of fireblight. Could it just be going into decline? I suggested they fertilize. (Cando, N.D.)

 A:  This tree has gone beyond the average life of a mountain ash by about 15 years. They are sensitive to poor drainage, alkaline soil, and root rot. It might be time to give the poor thing its last rites. Try fertilization to see if that gives it a little boost.

Q: My husband and I planted a row of apricot trees in 1999. This year they are producing a lot of fruit, although the worms or bugs are enjoying it more than we are.  The fruit is almost ripe but there are holes where the worms have been eating their way to the inside of the fruit. The fruit then turns brown, dries up and falls off.  Is there any thing I can do to prevent this from happening next year?  (Lisbon, N.D.)

A:  Pick up all the fallen fruit this fall. Spray the tree with Malathion as the leaves are unfolding next spring and hope that does the trick.

Q: I planted a maple tree last fall. This year the new growth is yellow with small leaves. It also has some black, poorly developed leaves. What is wrong and can it be corrected? (Portland, N.D.)

A:  It is most likely a soil pH problem. I doubt that you will be able to correct it because the problem showed up so early in the life of the tree. The tree also may have been planted too deep.

Q:  Last fall we planted an ash but I don't remember what kind it is. We over-watered so the leaves curled and fell off. This summer the tree has been doing great.  We have been careful not to over-water. The leaves are curling again and look a little brittle but not as bad as last fall. The leaves aren't yellowing or falling off. Should we be concerned?  (Fargo, N.D.)

A:  It sounds like it could be herbicide residue from a neighbor or in the backfill soil or mulch you are putting around the plant. If that isn't it, then it could be that you have it in a very high temperature and sunlight intense microclimate. Continue your careful watering. If it gets worse, send a sample to our plant diagnostic lab at NDSU.

Q: We dug up three arborvitae and one mugo pine in the spring of 2001 because the bottom half of each shrub turned brown. This was on the west side of our house. We planted a purple leaf sandcherry in the center, and an Anthony waterer spirea on each side. The sandcherry and one spirea are growing well. The other spirea did well in 2001 and started getting green branches in 2002 but then dried up and died. I replaced it with a new plant, which did well the rest of the summer. This spring it had several green branches but then it died in mid‑June. I treated both spireas the same this year. I cut back the dead branches in early spring and then fertilized with Miracle‑Gro when I saw new growth. I watered them during the dry spring, but not in June because of all the rain we had. The older spirea has bright pink blossoms and is 12‑15 inches tall. It is closer to the down‑spout of a rain gutter, so it may receive more water. The ground is mulched with small rock, except for a small area close to the shrubs. I want to try one more time next spring but I need some suggestions. My other question concerns two chiffon clematis ivy that were planted on the west side of a wooden fence in 1992. They bloomed occasionally during the first few summers but not in the last three. In late fall, I prune the plants down to the ground and cover the area with grass clippings. In the spring, they start to grow nicely and have branches several feet high on a wire trellis. They are next to a vegetable garden so they get lots of moisture. I apply Miracle‑Gro every two to four weeks but they don’t blossom.  Any suggestions?  (Beulah, N.D.)

A: It could be that it is too hot where you planted the spirea. It sounds like you have done everything else correctly. About the only thing I can recommend is to re‑work the soil completely, adding sphagnum peat moss and sending a sample of the prepared soil into our lab for testing to be sure there isn't a salt level that is causing the problem. As for the non‑blooming clematis, I'm stumped. Try backing off on the fertilizer next year or consider relocating it to a cooler location. I have been raised on the golden rule for clematis success. They need a warm location but with cool soil. I am not familiar with the chiffon clematis that you are referencing so perhaps it has cultural requirements that I am unaware of.

Q: I have a question about autumn blaze red maples. I recently planted four of them in my yard but I just read they are a hybrid of red and silver maples. I’m wondering if the roots will run on top of the ground like a regular silver maple, which is a pain to mow over. If so, mine are coming back out of the ground before they take hold. (E-mail reference)

A: I have never seen an autumn blaze maple that has produced a serious surface root system. You should be home free unless you have dense clay or soil that is highly compacted.

Q:  I have two peony plants. After the flowers fell off, I found four or five little nubs where the flowers were. Could these be seeds? Can they be planted and how do I go about planting them?  (Aberdeen, S.D.)

A: They are the seedpods but, for a couple of reasons, I want to discourage you from attempting to grow some from seed. They have an epicotyl dormancy that has to be overcome, which requires some timely temperature adjustments. The plants are usually not true to type and it takes several years for flowers to develop.

Q: I have three Colorado blue spruce that I planted about three years ago. They are doing great but I have a problem with rabbits. They ate a lot of the needles and branches. That was two winters ago. Last year I put up a fence to stop the rabbits. Is there any way to trim the trees to shape them? The rabbits ate out of the middle to about three feet up the tree. (Fargo, N.D.)

A:  I have never heard of rabbits eating spruce needles, especially three feet up the tree! Yes, you can prune to help reshape the tree. Spruce have buds along their stems where the needles are attached. Using an electric hedge shear is the easiest way to do it.

Q:  I have decorative retaining blocks I put around my trees and filled with decorative mulch. I have a ton of grass growing up through it. What can I use to kill the grass but not my tree?  (E-mail reference)

A:  Roundup is the best way to go. It will kill the grass and other green stuff but will not harm the tree as long as you do not spray the foliage.

Q:  My 3-year-old silver maple has yellow leaves with brown edges and spots. The leaves turn brown, crust up and fall off. The nursery said the tree needed iron so I gave it iron twice but that didn’t help. The tree produces new leaves so I don't think it's dying. (Fargo, N.D.)

A:  The nursery is correct. Most silver maples, especially the seedling selections, need supplemental iron. It will not correct the iron deficiency symptoms that have shown up already, but the new growth should be free of it. You can do direct foliar applications that don't last as long or you can inject it into the root system. Both approaches are effective. This is a physiological problem known as iron chlorosis. The pH of the soil is so elevated that iron becomes unavailable to certain species of plants. Silver maples are very sensitive to the problem. They need to monitored on a regular, timely basis. If it is allowed to get out of hand, the tree will eventually die.

Q:  We've been so pleased to have ripe tomatoes so early in the season but they have suddenly started to get hard and yellow at the stem ends. We are raising them in an earth box. The three varieties we have are cherry tomato, early girl and beefy boy.  Do you have any idea what is happening?  (Bismarck, N.D.)

A:  Just when I think I have heard about every problem dealing with tomatoes, someone comes up with a new one! I suspect something is wrong with the environment if it is hitting all the varieties equally.

Q:  On a TV gardening show the presenter talked about controlling insects in apple trees. He suggested painting a Styrofoam ball or something similar with red paint, suspend it in the tree and spray it with a sticky substance. Have you ever heard of such a control means? Would the sticky stuff be tanglefoot?  (Ellendale, N.D)

A:  Tanglefoot sprayed or smeared on an apple shape that is painted red will attract the female apple maggot and keep her away from the real apples. A couple per tree should work fairly well for the backyard orchardist.

Q:  I have had my ficus tree for about two years. Last year it was almost dead because of mites, scales and other problems. I took it outside last summer, sprayed it with insecticide and by September it was flourishing so I brought it back in. It flourished all year but today I noticed sap on several of the leaves. I haven't lost any leaves or had any yellowing. Should I take it outside again and spray it or should I just wipe the leaves with rubbing alcohol? If it is spider mites, where did they come from? (E-mail reference)

A:  Try rubbing the leaves down with alcohol to see if that does the trick. If not, then take it outside and spray with Orthene, which has systemic action. Your guess is as good as mine as to how mites and other plant pests find their way into a home to infest a plant. Probably on your clothing.

 

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu