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Don Kinzler, Published April 20 2012

Hortiscope: Soil sample may explain stunted tree growth

Q: I have looked forward to reading your column for years and hope you can give me some advice with a problem. We live on a farm southwest of Jamestown. There is a spot in our yard that is an ideal location for a tree to grow. However, every tree that we’ve planted on the site doesn’t die but never grows taller.

The leaves will get larger but the tree stays about the same size. My husband’s grandparents lived here before us and had the same problem. I have been told there was a pig pen in this same area more than 50 years ago. Could that have anything to do with this problem? Would it help to haul in dirt from some other area of the farm and try again?

Right now, there is a northern red oak planted there. The leaves get bigger each year, but that is all. What tree would you recommend planting? If we could get a tree to grow, it would be a focal point in our yard and create shade for our garage and house. Hope you can help us. (email)

A: Thanks for being a loyal reader for so many years. I have to admit this is something I never have heard of happening before. It must have something to do with the soil, but I have no idea what it could be. I would suggest that you get a sample of the soil sent to our plant diagnostic lab for analysis. For the address and mailing instructions, go to http://tinyurl.com/ckejd84. I suggest a complete test be run. You can download the form and send it in with about a pint of the soil you want tested. Be sure to get the sample from the root area of the tree.

There are at least a dozen trees that you should be able to grow and have it shade your house. Once we know the soil test results, I can make recommendations for you.

Q: Does a blooming Christmas cactus give off pollen, and are you aware of anyone who is allergic to the plant? (email)

A: In nature, pollination of the cactus is carried on by birds. No one should have an allergy to the pollen. I’ve never seen it on any lists or heard of anyone having an allergic reaction to cactus pollen. If the pollination of this cactus was dependent on wind movement, then the chance of an allergy would be elevated.

Q: I was reading your material on jade plants but didn’t find anything that fits my plant’s symptoms. I am familiar with many types of plants because I work at a home and garden center.

My roommate and I moved into our apartment in October. Her father brought her two jade plants that he grew from cuttings while in college in the ’70s. Both plants were vibrant and healthy, with plump, green leaves. I let them dry through the winter. The larger of the two even bloomed from December through January.

It was about that time that I began to notice small, black, raised dots on many leaves of the smaller plant and a few leaves on the larger plant. I know that it isn’t scale. The spots seem to be a part of the leaf. The dots almost look like blocked pores. There is no sign of mealy or a fungus of any kind.

It didn’t worry me at first because I know jades can be spotty, so I began watching them closely but did nothing different. The leaves of the smaller plant began to grow soft and droopy. The trunk is sound and there is no other sign of rot.

I assumed that the wilting was a lack of light because of the cloudy winters we have here in Chicago. It could have gotten cold, but our place never went below 60 degrees during the winter. Both plants sit in a room with southern-facing bay windows, so I moved the smaller one up to a place where it would receive more direct sun. It has been there for a few weeks.

Although we have had early, sunny, 80-degree days in March, it is not perking up. I have watered it once this month because I am afraid of root rot due to the lack of sun and water evaporation. I am noticing more black spots and some leaf drop. It also lost a small branch. The branch seemed to shrivel at the node and dropped off on its own.

Now I am noticing a few soft leaves and some leaf drop on the larger tree. My thoughts are that the larger tree is experiencing a bit of sadness from the lack of light and that the leaf drop is partly due to that and natural aging. My thoughts about the smaller plant are that it is a combination of delayed shock from being moved, lack of light and something bad in the soil that is causing clogged pores. However, I am afraid to repot either of these old trees because they aren’t mine, but I’m also afraid to do nothing.

What do you think? Will they snap out of it? Should I trust my instincts and repot the little guys? Afterwards, I’m sure they will need fertilizer. (email)

A: My analysis of your plant situation is that you made a couple of basic mistakes. You only watered once during the winter and you did not contact your roommate’s father about the care of such healthy and beautiful plants he gifted the two of you.

The black spots could be necrotic lesions from the dry environment in the root system and the atmosphere around the plant. Winters in Chicago dwellings require the use of central heating systems that can lower the humidity down to desert conditions. Misting with distilled or RO water, along with appropriate additional watering, during that time would have benefited the plant. Unfortunately, the regime you subjected the plants to resulted in physical (abiotic) damage to the plant tissue. The root system likely is dead.

Dead roots don’t conduct water and nutrients to the upper part of the plant. The top part of the jade is behaving like a cut Christmas tree. It is drying up and losing foliage. My best advice is to take appropriate cuttings from any firm tissue you can find and attempt to propagate the cuttings using conventional means.

Doing nothing is not going to solve the problem. Even if the roots appear to be dead, repot the plants in well-draining containers. Use fresh potting soil. There is an outside chance that some adventitious roots may develop at the base of the plants and revive them.

Other than this advice, with apologies to your roommate’s dad, start new with fresh jades and learn from the mistakes that were made. Good luck!

Q: I have had a patch of 15 tulips for several years. Last year, I got one bloom. So far this year, there are no blooms and the leaves seem very large and floppy. Their color also is a little pale. What is wrong with my tulips? (email)

A: It is difficult to say. If they have not been dug up and separated in all these years, it probably is the reason for the little or no flowering. Too late to do that now, but mark your calendar to do it sometime in mid- to late September.

Q: I just purchased two clump river birches in containers. There are three trunks in each container. The tag on the trees says to plant them 35 feet apart.

However, I do not have that much room. After comparing pictures of the tag and ones on the Web, it seems that the same species of birch are being planted much closer together (10 to 15 feet apart). The picture of the trees looks great and is what I want to accomplish in my yard. What would you do? (email)

A: Plant them as you wish. The separation distance is recommended to allow the trees to be viewed as individual trees. In nature, they have no problem growing closer together.

Q: Is there a granular form of chemical that is effective in controlling dandelions? Curtail and 2,4-D work well. However, both products are liquid, so I am concerned about the possibility of spray drift.

The chemical would be used in a yard in Bismarck that has a dogwood hedge and flower gardens.

F/S Manufacturing of West Fargo has a weed roller for chemical applications. How successful has it been, and have you had any exposure to it?

Controlling dandelions in the fall is the most effective way to do it, as you have said in your column. However, I am looking to do a spring application. I have used Scotts Weed-n-Feed with some success. How susceptible are dogwood and flower gardens to spray drift? If a liquid chemical is best, which product would be the best for my situation?

Thank you for any information or references that you can pass on. (email)

A: Dry-applied weed and feed combinations are not nearly as effective as the straight liquid application of a herbicide. We tested some products years ago at NDSU. It wasn’t even a close contest because the liquid applications won hands down.

Because your primary objective is dandelion control, the amine form of 2,4-D will do the job in a very satisfactory manner. There are three-way combinations available. However, unless you are dealing with a heavy invasion of a wide variety of difficult-to-control broadleaf weeds, there is no need to go that far.

Some of those materials remain active in the soil and can be taken up by the roots of woody plants. At a minimum, this would stress the plants. If overused (“revenge spraying”), the trees or shrubs could become so affected that it could lead to death. Spray drift can be avoided by using some common sense.

Avoid applications on windy days. Don’t overspray by soaking the weeds with herbicide. Follow the label directions because so much research and money have been put into developing descriptive and reliable labels.

All woody plants are vulnerable to herbicide applications in the early spring because fresh and tender new growth is emerging. If that is a major concern on your property, I’d suggest waiting until the foliage has fully expanded and stabilized. It doesn’t make them herbicide proof, but at least it lowers their vulnerability to any drifting.


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.