July 2, 2002

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have what I believe is a lemon tree that was planted by seed from Hawaii. The container that I have it in is 38 inches around the top and 12 inches deep. It stands about 6 feet tall, but the leaves have started curling and falling off. Can you tell me what is wrong with it? If it needs repotting, would Miracle Gro potting mix be good to use? I would like to save this plant if possible. I am sending you leaves so you can see what they look like. (Parshall, N.D.)

A: Your sample does appear to be from a lemon tree, but I do not detect any problems with the leaves you sent in. I suggest the following: Move the plant outdoors for the summer. Cut it back by about 1/3 its volume of branches. Repot using either the Miracle Gro product you mentioned or one of similar quality. Be sure the container is free-draining. Fertilize once a month during the summer.

Q: Last fall the wasps got in our apple tree. What they didn’t eat they just crawled in. so we got no apples. Is there something we can spray them with so it doesn’t happen again, and when would be the time to spray? Also, we have a May Day bush that is about 8 feet tall and a few years old. Can we now trim it, after it’s done blossoming, so it would be more of a tree?

A: The best control is to locate the wasp nest and have an exterminator take care of the problem. Don’t spray the apples. Yes, the May Day bush can be pruned into a tree!

Q: Recently a project in our farmyard has resulted in the loss of a fairly significant amount of the native prairie grass that has always been here. I am looking for an appropriate variety to reseed this disturbed area, which now has a mix of clay and black soil from a field. The native grass in places here is short and fine and perhaps there is more than one species. I would like information as to the best seed formula and where I can purchase it. This is northwestern North Dakota, Divide County. (Noonan, N.D.)

A: You would be in a short-grass prairie region. This would be an attractive ecological mix of grasses, sedges and wildflower species. Contact Prairie Restorations in Hawley, Minn. at 218-498-0260. This is their Bluestem Farm.

Q: Last year I noticed lumps on several leaves of our silver maple tree, but was able to pick them off or I removed the leaf. This year is much worse. Is there something I could spray on the tree, as it is only 3 years old. I also noticed there are no leaves on many of the upper branches. Could this be winter kill or something related to these lumps? (Hillsboro, N.D.)

A: The bumps are nothing more than cosmetic swellings from the early spring and feeding of a mite. It will not harm the tree, nor was it the cause of the dead branches in the upper part. Most likely, that was the result of our fickle winter weather!

Q: A while ago you gave an address and phone number for Park Seed Company. As I have lost my copy, I was wondering if you could share that information again. (Hawley, Minn.)

A: Gladly! Their number is 800-845-3369 and the website is www.parkseed.com. 

Q: Last year I sent you some photos taken of our ash tree and you stated that it was suffering from an invasion of the flower gall mite. Now I have enclosed some samples of three things that all came from this same tree. We don’t want to lose this tree in our front yard. Is there anything we can do? (Wahpeton, N.D.)

A: Your tree will be all right. You can spray with Malathion or Sevin if the insect problem persists. Nothing can be done about the galls now.

Q: The other day I bought some peaches and I was wondering, if a person plants the peach pit, will it grow into a tree? (Enderlin, N.D.)

A: It has the potential to become a tree. Whether or not it does is anybody’s guess. Most likely no, but even if it did, peaches don’t survive North Dakota winters.

Q: I was given a strawberry pot with holes in the sides that contain strawberry plants. I am wondering how to care for it in the fall and winter. I would hate to lose the plants for next year. (Harvey, N.D.)

A: In North Dakota, unless you heavily mulch the pot with straw, leaves or other forms of insulation, you will lose the plants. You might find it more useful to treat the plants as annuals, replacing them each year. I have known "peat moss jackets" to work quite well at getting container plants through the winter. A plastic bag is filled with peat and the container simply plunged into it, covering the tip as well.

Q: I have a question about my apple tree. It has always been healthy. It blossomed this spring, but now the bark is splitting away from the trunk on part of the west side and looking under that, there appears to be a couple of cracks in the wood. Three of the large branches now appear dead -- no leaves and blossoms are dried up. Do you know what the problem could be? (Langford, S.D.)

A: Sounds like a frost crack has developed (also called "sun scald"). Nothing you can do about it now. Hopefully the tree will heal over. Concerning the branches, it could be they have a girdling canker or damage from borers. In either case, I suggest removing the branches.

Q: I have two apple trees that are about 6 years old. They are about 12 feet high. For the first time last year, one of the trees produced seven apples. This year that tree had only two blossoms. The other tree has never blossomed. They are about 25 feet apart. They are very healthy looking. One is a Haralson , the other is a Minnesota something. Why aren’t they producing by now? (Detroit Lakes, Minn.)

A: Maturity for fruit production varies with the species, the care they are given and their environmental setting. Many home-owners have their trees planted in a lawn area that receives ample amounts of high nitrogen fertilizer. The tree roots compete for the nutrients and as a result, can stay in a vegetative (non-reproducing) state longer. You might want to avoid fertilization anywhere near the canopy spread of the trees. You may also want to drive a spade into the ground around the canopy edge to reduce the root system and perhaps stimulate fruit production.

Q: I have a peony bush in my planter. It has big double blooms but right now it is still budding and the buds are covered with big flies. They are just swarming on all the buds. Should we spray them with something? Do they hurt the blossoms at all? This happens every spring. I never see ants on them, just flies. (Leola, S.D.)

A: As you likely know, peony buds exude a sticky substance that is attractive to insects, which usually turn out to be ants. In your case for some reason, these flies got there first! If they are annoying you, spray; if not, ignore. They are probably not hurting anything, so should not pose a problem to the plant.

Q: Enclosed is a leaf from my neighbor’s tree. I am wondering what the disease is and if it can be sprayed and with what. I am afraid our trees will be next, but as of yet, our trees are okay. (Breckenridge, Minn.)

A: You and your neighbor have nothing to worry about. What you are seeing is callus tissue growth from the early season feeding of mites. Their damage is largely cosmetic, not destructive, and requires no spraying on you or your neighbor’s part. Next season they may be gone, or they may be back, and if they return, you still have nothing to worry about. Technically this malady is called spindle gall, caused by eriophyd mites. It is an interesting effect, so enjoy!

Q: When peonies are done blooming, can they be cut back or should I leave them? Also, my daughter has cottonwood trees she planted five years ago. This year they have only leafed out the bottom half. Will they eventually come back? (Dupree, S.D.)

A: Allow the peony foliage to remain going into winter. The top half of the poplars have probably been attacked by borers. There should be some evidence of holes or sawdust. That being the case, they will not come back.

Q: We have a problem with zucchini plants. We have nice big plants that bloom every day, but the blossoms close and fall off and there are no zucchini on the plants. We have fertilized the ground and we keep it moist. Please tell us why there are no zucchini forming. (Mobridge, S.D.)

A: The zucchini are producing only male flowers -- common initially -- then they begin producing some female flowers which will then, of course, bear the fruit you are looking for.

All you need for now is patience. I’ve never known anyone who grew these squash to be deprived!

Q: We have a yellow tea rose bush on the east side of our home. It is beautiful and loaded with blossoms. It is about 4 feet high. There are many runners coming out that are also blooming. Can they be dug up, and will they grow and blossom? If so, what time of year would be the best to dig up and plant? (Cooperstown, N.D.)

A: Very likely the sprouts you are seeing are from a vigorous root stock that is different from the rose flower you are appreciating. They will certainly grow on for you, but I’d suggest waiting until next spring to do the digging -- get them before they leaf out.

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