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Don Kinzler, Published November 09 2012

Hortiscope: Tree’s problem likely weather, not dog urine

Q: I have three red maple trees that I planted several years ago. They were beautiful before this spring. One did not have a full production of leaves. Now that fall is here, the other two trees have dropped their leaves. The tree of concern still has its leaves, and small, tan mushrooms have surfaced near the trunk. My neighbor has a dog that is kept in all day. This spring, the dog’s urine killed three spots in my lawn. I learned that his urine probably contains heavy nitrogen that overfertilized the lawn and caused the burns. Is it possible that the dog did his business on the tree and that is causing the problem? Do I have cause for concern? (Michigan)

A: Are you sure the neighbor’s dog is a he? If the dog is a male, he likely lifted his leg on yours and every other tree in the neighborhood. Males seldom relieve themselves on the grass. That is more female dog territory.

What I think your tree got hit with was the same things that occurred across the upper Midwest last winter, which were mild temperatures, low snow cover and an early spring that was followed by a sudden drop in temperature. These factors caused a major debilitation of maples across Ohio, Michigan, Minnesota, Wisconsin and the Dakotas.

The typical symptoms are pretty much what you describe. In many cases, one-quarter to one-third or more of the canopy did not leaf out and there was little to no new growth. It also causes the strange reaction going into the fall that you are seeing.

The mushrooms are an indication of rotting organic matter somewhere in the soil caused by excess thatch, rotting wood, fairy ring development or decaying roots. While at least three things are going on here (dog urine spots, funky growth on one of the maples and mushrooms), I doubt that the three are connected. You can contact the Michigan State University Extension Service in your county to examine your situation and make a diagnosis.

Q: We had four beautiful hanging ferns on our porch. I was away, so they were damaged by frost. When I returned, they were all brown except for a few leaves on each plant. We had planned to put them inside for the winter. Is there hope for them? Can we put them in a 50- degree room in the basement that gets little light during the winter with the hope the plants will recover next spring? (email)

A: Getting nipped by a light frost is one thing, while getting clobbered by a hard freeze into the mid or lower 20s is something else. It depends on how long the temperatures stayed at the lethal level, so I cannot give you an accurate prediction if the ferns will come back next spring. Being the eternal optimist, I predict that they will recover. You also have nothing to lose by giving them a chance.

Q: I have two questions about my spider plant. The spider’s leaves have turned dark about 2 centimeters underneath the tip of the leaf. Also, the plant’s leaves have turned black near the roots. I purchased the plant about three weeks ago and placed it next to a window facing north. The first time I watered the plant, I may have overwatered it because the water soaked through the entire pot. I am not sure if this is the cause of the problems.

At night, I have placed the plant under indirect light (normal room light) until about 2 or 3 in the morning. I have been peeling off the baby leaves because they are dying. I was just wondering why this is happening and if there is anything I can do to prevent this from occurring. I have attached seven pictures of the plant. (email)

A: In looking at the photos, it is impossible to determine just what is causing the blackening that is showing up at the base. Here is what I know and have practiced for more than 20 years of living with chlorphytum. Water the plant generously during the growing season, which is spring to fall.

We set our plants out in the spring around or a little before the Memorial Day weekend. It depends on the weather. We allow Mother Nature to provide most of the water but supplement it when we are without rain for 10 to 12 days. When we have it indoors for the winter months, we use reverse osmosis, distilled or snowmelt water. However, we allow the mother plant to dry out somewhat more than in the summer. In other words, benign neglect seems to work well with this plant as far as watering is concerned during the winter months. These plants don’t appreciate supplemental lighting, so back off on that. In fact, short days are needed to set up the new plantlets being produced. If there is a clue as to what your problem is, it may be tied to contaminated or fluoridated water and too much light. From the photos, the mother plant looks healthy. I would recommend some tough love by removing the affected plantlets. Change your cultural practices to see if the new plantlets that emerge during the winter are free of diseases.

Q: My husband and I are planning on planting two rows of trees on a lot we purchased. The tree rows would run east and west. We would like to plant one row of blue spruce trees. Do you have any suggestions as far as deciduous trees for the second row? How far apart do you suggest planting the blue spruces and how far apart do you suggest having the tree rows? (Bismarck)

A: Space between plantings is really a function of how fast you want enclosure. Some want a wall of evergreens as soon as possible, so they will space the trees 5 feet apart in the row. They will also take a deciduous species, such as a hackberry, and space them the same distance. It is more expensive because of the higher investment in planting stock.

A more modest, but effective spacing, would be to space the evergreens 8 to 14 feet apart and the deciduous trees 10 to 16 feet apart. The spacing between the rows should be somewhere within these ranges. Allow enough room for equipment to be used for weed control without physically damaging the plantings. I mentioned hackberry being a good deciduous species to consider. Others might be lindens, silver maples (local seed source or selected cultivar), black walnut and bur oak.

Q: I was reading all of the information about linden trees on your website, but my question still is unanswered. We have three linden trees in our yard. We have lived in our house for four years. In the last year, we have noticed large branches falling off the trees. I have heard of linden borers and fungus that can affect the trees, but no one talks about gigantic limbs falling off. We have holes in the trees as well. Any insight on our situation would be extremely helpful. We love these trees and would hate to get rid of them. However, our luck seems to be running out on not having any damage being done to our neighbor’s or our property. (email)

A: It sounds like a couple of issues working on your trees. One problem could be sapsuckers. I encourage you to make contact with a certified arborist in your locality to inspect the lindens to see if they can be saved. Go to http://tinyurl.com/69fgll3 and provide the requested information to get a listing of certified arborists in your area. Be sure to check for credentials and insurance.

Q: I have a gentleman who has trees with Dutch elm disease. He is interested in doing the fungicide injections. Just wondering if you have a rough estimate on what that costs. He has a lot of infected trees. Unfortunately, they are being used as a windbreak around his farmstead. If a tree is showing symptoms, would fungicide injections stop the progress of the disease or is it best to just do the trees that appear healthy? (email)

A: The fungicide injections are preventive only. He may want to think twice about trying to protect the trees in his shelterbelt because of the expense involved. Generally, such injection treatments are used for high-quality trees, not ones in shelterbelts.

I’m not up-to-date on costs, but it depends on the caliper size of the tree. The cost usually runs in the hundreds of dollars for a decent-sized tree.

Q: I have a number of large spruce trees on my property. We just noticed that a few of them in different locations have a number of branches turning yellow. The information I have read on websites seems to indicate that they have a fungus. However, the remedy calls for spraying the trees in August. Our average daily temperature in late October is in the mid-50-degree range. Should I assume that this is caused by a fungus? Is there anything I can do now to help the trees? Will this kill them? Thanks for your help. (email)

A: Can I assume you live in North Dakota? If not, then contact with your county agent where you live. There are too many variables to give you an answer based on what information you’ve provided. I don’t want to make any incorrect assumptions and get you going down the wrong path. If you are in North Dakota, then you need to send me photos and a sample or two of what you are talking about. Send the material to the address at the end of this column.

Q: My wife wants to cut my dieffenbachia off at the top. I’m rather distressed because it has taken me a long time to grow it to the height it is. It has six to nine leaves at any given time and has a thick stock. However, it has reached a height where it seems to be having a hard time standing straight. Even the supports are giving way under the weight. When I added more supports, it appeared that I broke some roots and new plants have sprung up. Should we transplant these new stalks or just call it day and cut the top off to let the newer plants take over? Thank you for any input you may have. (email)

A: You have a couple of options. You can air layer or cut the cane back to about a 4- to 6-inch stump. Cut the cane up that you cut off into 4- to 6-inch pieces and root them into new plants. Dieffenbachia easily roots from cuttings. I’ve published a “Home Propagation Techniques” publication that will help guide you through the process of propagation. It is 16 pages long, so you might want to look at it online before downloading. The publication is at http://tinyurl.com/88po8ru. This way, your wife won’t be frustrated by not being able to cut back your beloved plant. She now can do it without losing anything. In fact, she is increasing the chances of giving some away as gifts.


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 ronald.smith@ndsu.edu.

For answers to general horticultural questions, go to http://www.ag.ndsu.edu/horticulture.