Don Kinzler, Published July 06 2012
Hortiscope: Hackberry tree growing too close to houseQ: I have a hackberry tree that has started to grow in the middle of a rose bush. The ground is dry, hard caliche. For the past three years, we have suffered through a drought. I appreciate any tree that can survive in this terrible soil. However, when I inquired what the tree was, the lady identified it as a hackberry and said it would be best to destroy it because it seems to break off in large chunks and could damage the house. The tree is a few feet from the house and has grown to about 6 feet in height in less than a year. Is it a hazard or should I let it grow a couple of years to see if it seeds another tree farther away from the house and then cut it down? (Lago Vista, Texas)
A: If it is a hackberry, the common hackberry and the sugarberry are known for being tough, wind-resistant trees, so I think the comment about pieces of it falling on your house are somewhat misleading. As far as I know, neither tree has ever been tagged with that reputation.
However, it is growing too close to your house. After it goes dormant this fall and all the leaves are gone, I would strongly suggest that you dig it up and plant it where you want. As a young tree, it will transplant quite successfully.
That way, you would be able to enjoy the shade and durability this tree species has the potential to provide as it reaches a mature height and spread.
Q: A couple of years ago, my neighbor built a fence along the perimeter of his backyard. This year, all of my grass within 6 to 8 inches of the fence died.
This did not happen the previous years. A couple of dandelions and a wild mustard plant survived. A tag on the bottom of one of the boards says micronized copper azole. Could the dead strip be caused by this treatment being rinsed off the boards and onto the grass? I am to the west of the fence, so could compaction from snow accumulation have been a factor? (West Fargo)
A: Yes, the dying of the grass very well could be from the copper compound used in treating the fence boards. It may have leached out from rain and irrigation events. It was employed years ago as a preservative in the nursery industry to slow the rotting of burlap used to ball the roots. Snow compaction can cause the same thing. However, that usually happens when equipment is driven over the snow and forms an ice crust, which wouldn’t be the situation in your case.
Q: I’m having problems with my rhubarb. The plants came up fine this spring, but then the stalks and leaves turned yellow and dried up. I did give them Miracle- Gro, but that didn’t help. I bought a new plant from a master gardener and planted it at a different location. It was doing fine, but now it looks the same as my other plants. I’ve had these plants for many years, so I sure would hate to lose them. Could you please give me some direction? (South Dakota)
A: For an accurate analysis, you need to send a sample of the plant problem to the plant diagnostic clinic at South Dakota State University. Go to http://tinyurl.com/d26ykwk and follow the directions to submit a sample.
Q: The leaves on my morning glories are being eaten by some pest. However, we cannot find any bugs, eggs or flies on the leaves. My wife has sprayed the leaves with Orthonex Systemic Insecticide, but that hasn’t worked. How would you assess the situation, and what can I do to stop the obliteration of my leaves? (email)
A: The absence of any visible insects is a good indication that the pests are night feeders. We have had instances of climbing cutworms that bypass the stems and go after the leaves for some reason. If you look around the base of the plant in the top inch of soil, I’m willing to bet that they will be found. If you can’t locate them, get some diatomaceous earth and work it into the soil next to the base of the plant. The diatomaceous material should be thick enough that you have the soil surface covered. That should do the trick.
Q: I have a problem with two Norway spruces I planted about a month ago. My soil is very heavy clay. One of the trees is doing well, but the other tree is not.
It has turned orange and the needles are falling off. I don’t think it is dead because it is green under the bark. Is there anything I could do for this beauty to help it? I hope it’s just a little shock so the problem will go away.
However, my gut is telling me it needs help. I have a few other spruce and Austrians that are fine but are a dull green. Do you think a shot of iron or something else might help? Thanks a ton in advance. (Montana)
A: In trying to figure out what is going on with your trees, I get the inkling that it may be a rust fungus that has hit some of them. Being in Montana, I cannot imagine you being in a swampy area where the alternate host for spruce needle rust is anywhere nearby, so it could be an autoecious form of the fungus.
This means the fungus does not need an alternate host to complete its life cycle. These rust fungi are seldom lethal to the tree in spite of there being some needle loss. Generally, the infection will subside as the weather improves.
There is no cure, but you can protect your good tree by applying a fungicide such as Bravo, Thalonil or Chlorothalonil.
Q: A couple of years ago, we lost five trees to Dutch elm disease. We now have two that came up from seedlings and are growing behind some flowering bushes. I would like to keep the trees because we lost so many. However, I am concerned there still is a threat of Dutch elm disease in this area. Also, will the trees kill the bushes as they grow? I believe one of the bushes is a flowering almond, which is beautiful in the spring. On another topic, I also have a small rose bush that I cut the canes back in the fall after the first freeze. I believe I read in one of your columns that they should be cut back in the early spring. Is that correct? And how far back should I cut them? I truly appreciate any advice you can give us. (email reference)
A: With the reduced population of elms across America, the epidemic has long since stopped. In addition, there are protective measures that can be taken that didn’t exist when the disease was discovered in Ohio in 1930. We spent 50 years trying to catch up with the rampant spread of Dutch elm. The fact that these are seedlings is a good indication that the parent tree is a survivor and has some degree of immunity that probably was passed on to the offspring. In a nutshell, the trees are safe for the foreseeable future. Sooner or later, the trees will become competitive with the bushes, so one or the other will have to go. In Ohio, I used to cut the roses back in the fall to get them small enough to cover. I would go back in the spring to cut out any branches that may have died during the winter or were damaged.
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 email email@example.com.
Q: I had a lady come in with peonies that look brown. She said that none of her other peonies look that way and that this plant also produced flowers that looked brown last year. She’s wondering what the problem is and if it is going to spread. Have any ideas? My first guess is that it would be something subsurface. Could it be botrytis or maybe the flower was planted too deeply? (email reference)
A: This very likely is the fungus botrytis cinerea. It attacks stems, buds and leaves. This disease can appear at any time of the growing season but is most common in cloudy, rainy weather. It begins early in the spring when the shoots are about 6 inches tall. Young stalks discolor at the base, wilt and fall over.
This wilt and shoot death may continue throughout the summer if conditions are wet. Other symptoms during the growing season include large, irregularly shaped spots on the leaves and brown flower buds that are covered with a mass of gray, fuzzy fungal spores. The fuzzy fungal spores that are produced after a rain or watering are characteristic of a botrytis infection. Good sanitation, such as the prompt removal of spent flower blooms, and following cultural recommendations will reduce botrytis problems greatly. Fungicides are of limited effectiveness against this disease. However, a basic copper sulfate or Mancozeb can be applied early in the season when the shoots are about 6 inches tall to help protect the plant. Spray all plant parts to thoroughly wet the foliage and soil. It is very difficult to stop any disease in the season it appears.
Prevention through proper site selection, cultural management and good sanitation is by far the most important step in reducing the incidence and spread of disease. Cultural measures, such as improving air circulation, watering early in the day and watering only at the base of the plant, will greatly reduce infection. As a sweeping generalization, established peonies can get along without any water except for what Mother Nature provides. The removal of any spent flower blooms, infected buds, leaves and stems is best done during a dry, calm time of the day. It is very important to clean your pruner by dipping it in a 10 percent bleach solution or by spraying it with a 70 percent rubbing alcohol mixture after cutting off diseased plant material and prior to pruning any healthy plants. Carefully dispose of any infected plant material but do not discard this debris in your compost pile. In the fall, cut any diseased plants back to the ground or just below the ground. Add well-composted organic material as a light mulch in early fall to help add nutrients and improve the soil. This organic compost can be lightly worked into the top inch or two of soil. Fungicides help protect plants from disease but are not very effective at curing a problem once it has started. A fungicide can be applied to protect new shoots, leaves and buds from infection. Carefully follow label directions.
Q: On more than one occasion, you helped me in various ways solve myriad horticultural problems. Although retired for almost seven years, I still get questions from people, which is the reason for this inquiry. I was asked to look at a green ash tree that is in rough shape. Its overall condition is poor because it has a large number of dead or dying branches. I checked the bark for signs of bark beetles and did find some entry holes, but not in large numbers.
On some of the affected branches, there appears to be a girdled ring around the entire branch and a series of tiny holes directly in line with each other. It seems these areas are weakened and the branch sometimes will snap off. I don’t know if any of this might sound familiar to you, but I hope you might be able to give me a little insight. I will try to collect a sample and send it to you for further analysis. (email)
A: The ash tree problems you describe sound like a combination of twig girdler and ash/lilac borer. There are many species out there, so exactly which one that would be attacking this particular ash I cannot say. Twig girdlers are a variety of the longhorn beetle. Ash/lilac borers are a type of wasp that lays eggs beneath the bark. It is the larvae of the borers that cause the damage. Both are difficult to control at the discovery stage because the damage usually is quite extensive. Attempts to control the borers often come when what is left alive is not worth the effort or expense to save. Systemic insecticides will work, but slowly. Topical insecticides also work. However, with large trees, it usually is not advisable to spray that much insecticide into the environment. We are having a small epidemic of aphids feasting on our ash trees in North Dakota and western Minnesota. Ash leaf curl aphids multiply exponentially and feed on the underside of leaves. This causes a shower of aphid droppings to rain down on anything or anybody. Two systemics on the market are Imidacloprid (Bayer Advanced Tree and Shrub Insect Control) and Orthene Systemic Insect Control.