August 26, 2004

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I planted a dwarf apple tree eight years ago. The deer love to chew all the new growth back each spring. I put nylon meshing around it each year, but take it off once I think the deer are gone; however, they always fool me. The tree is very stunted and has dense branches. Should I take a lot of the small branches off and leave it to see if it will eventually bloom and produce apples? (e-mail reference)

A: Don't give in to the deer so easily. Spray the new growth with hot pepper spray or Deer Away. You can hang Irish Spring soap bars around the tree, swatches of human hair or spray the area with predatory urine. These defenses may work alone or in tandem. Yes, do some cleanup pruning. Deer don't prune apple trees with any design in mind, just taste!

Q: I ordered six ruby red hydrangeas from Springhill Nurseries. One is now blooming, but the bloom is pink, not red. If I had wanted pink, I could have purchased them right here in town! (e-mail reference)

A: The plants probably need a little more lime. A lime application will help darken the color, but test your soil first. I'm willing to bet it is on the acidic side, with a pH level below six. Also, this particular cultivar starts out pink, but darkens gradually through the season. It should turn a deep carmine pink, or red as some prefer to call it.

Q: I have snow-on-the-mountain growing around my house and it is spreading more than I would like. What is the best way to get rid of it? I also have trumpet vine in the same area that I would also like to remove. Can you recommend a climbing vine that would go up a chimney, but not damage it? I read that trumpet vine and Virginia creeper can damage masonry. I have another bed that is constantly invaded by what I have been told is pin cherry (a shrub, with shiny leaves and dark berries). The pin cherry shrubs are in my neighbor's yard, so I can't remove them. I would like to plant something like periwinkle in that area. (Email reference)

A: Roundup or a dicamba containing (Trimec) herbicide will usually do the trick. All the vines I know of that are self-supporting have some kind of holdfast that gets into the brick and mortar. Unless the brick work is weak and old, the holdfasts from Boston ivy, Virginia creeper or any other vine should not be destructive, just unsightly after they have been removed. Concerning the pin cherry, birds consume them and then deposit the seeds. The seeds will germinate even after passing through a bird’s digestive system. Vinca minor (periwinkle) should do well as long as there is some shade.

Q: I have a coneflower plant in my garden. It has plenty of buds, but they are bent over like they are wilted. Can you tell me what the problem is? We have had a lot of rain lately. (e-mail reference)

A: Vigorous coneflower growth will be hampered if the soil is heavy clay and stays wet after a significant rain event. I lost an entire experimental planting years ago after a 100-year rain event.

Cut a bud back into the stem and examine it for borer activity. These plants can do beautifully left alone in the wild, but begin to have problems when we bring them into our cultured landscape, where we heap too much attention on them.

Q: A homeowner says she has many pine needles. Can they be used as mulch in a garden? If not alone, could they be mixed with something? (Dickinson, N.D.)

A: Pine needles make an excellent stand-alone mulch.

Q: A fellow in town called this afternoon wondering why his peonies didn't have any ants and the blossoms are not opening up. Should he have a little more patience? It has been cold and wet up here! (Lakota, N.D.)

A: Ants have nothing to do with peonies blooming. Cool and wet weather is the problem and probably the specific location of the plants. Blooming will be delayed if the temperatures are cool and the plants are not being baked in both direct and reflective sunlight. You are right, patience is the answer!

Q: How and when should a birch tree be trimmed? (e-mail reference)

A: Birch trees should be trimmed as little as possible and only when absolutely necessary (when there are dead or broken branches). You may want to trim after the leaves have fully expanded to cut down on excessive sap flow.

Q: My husband and I built a house in the spring of 2000. There is a wonderful burr oak about 20 feet from the back of the house. There has been no further construction and the tree has been in perfect health (from what I can tell) until this spring. Last year's dried leaves still remain on some branches and it did not bud. I see a woodpecker from time to time and when construction started there were a couple of large branches cut off that were facing the house. Is there anything I can do to save it? (Hugo, Minn.)

A: Check around the base of the trunk. It would be good if there is a flair on all sides. If it has a pole appearance going into the ground, not good. The fact that the leaves are still on the tree from last year means it did not go completely into dormancy. In either case, it sounds like it could be dead. I can't help but be suspicious of the contractor's activity around the tree during the construction of your home. Contact Gary Johnson at the UMN Urban Forestry Department. He is an arborist and probably knows his stuff better than anyone else in North America. At the very least, have the tree evaluated as to the cause of death, how sound it is and how quickly it needs to be removed to eliminate any hazard potential. Removing the tree may devalue your property somewhat. Gary can assign the value lost. I'm sure that if Gary is too tied up right now, he can recommend someone equally competent.

Q: I have a variety of snow-on-the-mountain that is not variegated. It showed up in the middle of a variegated patch. Is this a common variation or do I have something wonderful? (e-mail reference)

A: Nothing wonderful, sorry! It is a simple reversion back to the original form. Cut it out unless you like that form better than the variegated. The green has more vigor and will eventually overcome the variegated plants.

Q: We were wondering what type of fertilizer is appropriate for hollyhocks. (e-mail reference)

A: Anything that promotes blooms. Rose fertilizer, for example, will do a good job. It is low in N and higher in P and K.

Q: How close to a well system can I safely plant a tree? The tree I'm considering is an American linden. (Harvey, N.D.)

A: A well system should not be a problem to any great extent. Wells are enclosed unless they are hand-dug, which I haven't seen in more than four decades! A linden will probably do fine if it is planted anywhere from 30-50 feet away, assuming your concern is the root system.

Q: We have two rows of evergreens on the north and east edges of our property. In the past few years, we have been noticing that the needles, especially on the north side of the trees, are missing almost halfway up the tree and on the inside branches. Is this needle cast or some type of blight? What can we do about it? I have been reading that they can be sprayed with a fungicide, but timing is important. What is the right time and what fungicide do you recommend? My husband is afraid we will lose all the trees. (Lamoure, N.D.)

A: There is no way to tell for sure if what you describe is needle cast. Send a sample to our plant diagnostic lab. The address is: NDSU Waldron Hall, Fargo, N.D. 58105. Be sure to also send some healthy branches. The diagnostician needs to see where the pathogen is active. There will be a nominal charge for the lab work.

Q: Our yellow daylilies are no longer a bright yellow. They are taking on an orange tint. This is the fourth growing year that we have had them. The first year we had them in planters around the deck rail and they were a beautiful bright yellow. At the end of the growing season, we planted them in one of our beds in the yard. The second year they were once again yellow. Last year we noticed the flowers had a slight orange tint. This year they look very healthy, but they are now more orange than yellow. Is there something we can do to maintain the yellow color? The daylilies are planted in front of our azaleas. Could the azalea plant food be causing the color change? (e-mail reference)

A: Although I am unaware of a fertilizer causing color change in daylilies, it has to have some kind of connection, especially since the azaleas require such an acid soil.

Q: My husband and I purchased a red maple in June. I watered it when we delivered it home. The next day the leaves on that side looked wilted and dying. Please help with a solution to this problem. (e-mail reference)

A: How was the delivery made? Was it hauled in an open bed truck or with the branches hanging out of the trunk of a car? Both could cause the wilting you describe. In many cases, the tree will recover, but look bad during its initial growing season.

Q: We purchased a hackberry tree in a pot from a local nursery. It was a holdover from last year, so it was terribly root-bound. We took the roots and unwound them from the circular pattern they were bunched in and planted the tree according to the directions. The tree remains green if you scratch a branch or the trunk, however it has no buds or leaves. Is this tree a goner? (Jamestown, N.D.)

A: The hackberry is a strange tree. Sometimes the dormant ones need to be “sweated" to get them to bud. So hang in there and see if it will leaf out when our hot weather finally arrives.

Q: How do you get rid of hollyhock weevils? (e-mail reference)

A: Spray with Sevin, Malathion or Orthene.

Q: I've been reading through some of your jade plant questions and answers and I didn't find any mention of deformed new leaves. The leaves are normal coming out from the stem, but halfway down, the leaves cut in and form a point similar to a spade. Will they eventually grow out of this shape? I am giving it more light. (e-mail reference)

A: Insufficient light causes most foliage deformities. So your increasing the light may do the trick. Other problems may be a genetic glitch, physical damage, air pollutants or chemicals in the soil.

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

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