March 14, 2002

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Do all hackberry trees produce the little reddish purple berry fruit? I don't recall the one on our ranch producing them, nor the one in the back of my parents’ yard. The one in my parents’ yard has a 3- to 4-foot trunk like most hackberries. It has corky like veins running throughout the exterior of the bark that covers the whole tree. There does appear to be tiny seeds in the leaves, but nothing like a berry. It is identical to the one on the ranch and I always assumed it was a hackberry. Do you have an opinion? (E-mail reference)

A: Most hackberry trees will produce the seed. The amount depends on the growing conditions. The "seed" you are seeing in the leaves is really a nipple gall, caused by a very small insect called a psyllid. They lay eggs in the emerging leaves and the larval development causes the nipple-like growth to develop around them. Their damage is cosmetic, not lethal. It sounds like you are describing a hackberry.

Q: How do I prune back my hydrangea, and when do I do it? (E-mail reference)

A: I will assume you are talking about the Annabelle hydrangea. Prune it in the early spring before it comes out of dormancy, back to about 4- to 6-inch stubs.

Q: I have a problem and I need your help! How do you arrive at a monetary value for damage done to three black walnut trees that are 30 or more years old? The trees are on private property and all of the lower limbs were cut off by the city. These trees have never been pruned before. (East Grand Forks, Minn.)

A: Good luck! Contact the city forester or any competent forester or horticulturist knowledgeable in tree evaluation. There is a rational procedure that is followed and respected by most appraisers and insurance companies.

Q: In our front yard we have two silver maples between 30 and 40 years of age. The root system is a problem in our yard. We have a small yard and half of it is taken up by roots. Our driveway is cracking and the trees are about 20 feet away from the house. We have to remove them. One company will pull the stump and roots and put top soil back. Another company wants to grind the stump and roots, then remove the shavings. We were thinking of having them ground instead of removed because of the cost. Is it a wise choice? Or will we be filling holes for years to come? (E-mail reference)

A: It all depends on the contractor. I have seen many successful grind-out operations where a quality landscape could be developed after the removal. I would ask the contractor if he can supply you with the address of some past clientele for your reference. If he refuses or cannot, then a red flag goes up as far as I'm concerned. The grinding would be less destructive an operation so should cost less, but you need to see first hand the quality of this person's work before making a commitment.

Q: I would like to find the "reddest" and tallest growing variety of red twig dogwood. We are not interested in long term trees, just tall straight trunks 7- to 9-feet high and turning red as possible in winter cold. (E-mail reference)

A: You can go either with Cornus alba, (Tatarian dogwood), which has bloodred twigs in summer, the C. stolonifera (redosier dogwood) with the same qualities, both being shrubs, or the Prunus maackii (Amur chokecherry), which is a small tree that has an attractive copper-colored, birch-like bark.

Q: I have a client who likes tomatoes but has troubles with the seeds because of diverticulitis. He would like information on availability of seedless tomato varieties that could be grown here. (Cavalier, N.D.)

A: There is no such thing, as far as I know, as a completely seedless tomato. There is one that is touted as nearly seedless, and we have grown it. It is called Oregon Spring and was developed by Oregon State University. The oxhearts are low in seed (just from experience) but this variety is the only one that touts seedlessness as a quality.

Q: I have a ficus that we are constantly cutting back. The other day as I was cutting off dead branches, I noticed that there were little black spots on the branches almost like bugs. They look like a small black bug sitting on the branch but it is liquid, almost like a mold, sap, or seeping. Can you tell me what this may be? (E-mail reference)

A: You have discovered oyster shell scale. It’s tough to get rid of. If the scales are confined to a few branches, cut them off immediately. If the tree is badly infested, dump it.

Q: I think it was in your column where I read that these striped-winged flies come from the ground. I have never had them as bad as this year. We put an addition onto our home last summer and I wonder if breaking up the ground for the footings made the flies more abundant. If the flies come from the ground, is there anything that can be done to the area around the house this summer to cut down on the population? Maybe it is because of our mild winter, but they are terrible. Any suggestions? (Hitchcock, S.D.)

A: You need to employ a professional exterminator at this point. Home remedies will not work. The flies are the result of mild winter weather causing a premature hatching.

Q: I just received a Calla lily as a gift. I've never done any sort of plant care. What kind of pot am I supposed to put it in? How often do I water it? What else do I have to know? (E-mail reference)

A: The gift giver was smart to give a novice such a durable plant! Give the plant plenty of water.

Give it bright light like an east or west facing window. Avoid direct summer sun. Fertilize with a houseplant material such as Schultz's. Divide the plant once a year during a period of inactive growth, and place in separate pots, preferably clay, with free drainage, placing the pot on a saucer.

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: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu