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Published September 23, 2011, 12:00 AM

Hortiscope: Best to divide bulbs when they’re dormant

Q: I have three pots filled with amaryllis plants. I start watering the plants in late winter or early spring. After blooming, I put them outside for the summer. All the pots have side bulbs that I want to separate and repot. At the end of summer, the leaves die back, so I stop watering them and put them into the garage. They rest there until I start watering them again.

By: Don Kinzler, INFORUM

Q: I have three pots filled with amaryllis plants. I start watering the plants in late winter or early spring. After blooming, I put them outside for the summer. All the pots have side bulbs that I want to separate and repot. At the end of summer, the leaves die back, so I stop watering them and put them into the garage. They rest there until I start watering them again.

When should I separate the side bulbs? Should I do it during the winter while the bulbs are dormant or earlier in the fall so they have time to root and become established in their new pots? (email reference)

A: While they are dormant is the best time to divide the new bulbs. Start watering the new bulbs at the same time you start watering the mother bulbs again. Typically, the new plants will produce foliage the first year or two before finally flowering in the third year.


Q: We have an apple tree that is approximately 20 years old. I believe it is a Nordland apple tree. This tree produced many apples year after year for a long time. Three years ago, we had the tree pruned. I think it was in the fall. The tree did not produce fruit the next year, which I assumed was because of the pruning. However, the fellow who did the pruning assured me that he had done it correctly. The second year after the pruning, the tree had a few apples. This year, the tree did not produce any fruit.

I am not sure what to think. As far as I know, nothing else has changed. We did get a new neighbor who took a crab apple tree out of their yard. I wonder if those two trees were pollinating or somehow assisting each other. We have other apple trees that are producing fruit, but they are a different variety. Any suggestions you have would be greatly appreciated. (Alaska)

A: You might have identified the problem. Some apple species cross-pollinate better than others. Your apple tree may have been particularly in tune with the pollinating times of the neighbor’s crab apple tree. I’d suggest contacting the Extension Service folks in Alaska to see if someone can name a pollinator species for your particular tree. To find an agent, go to www.uaf.edu/ces/gardening/. Alaska has a very sharp group of horticulturists and foresters who are in the best position to help you.


Q: Will cutting the lower branches off a blue spruce hurt the tree? The branches are twisted up with weeds during the summer, so it is difficult to mow under the tree. During the winter, the lower branches are on the ground because snow piles on them. The branches are a bother, but I really like the tree and don’t want to hurt it. (email reference)

A: You won’t hurt the branches one bit by cutting them off. Cut the branches back to the trunk but not into the trunk.


Q: I lost a young oak to iron chlorosis several years ago. One of my maple trees now has it. I’ve been giving it liquid iron supplements all summer. However, now that fall is setting in, it once again is showing signs of chlorosis. I’m not sure what to do. Another new maple, but a different variety, has looked very healthy all year. However, all the new growth has leaves that are small and leathery. Not sure what that’s about. Do you have any ideas? (Boulder, Colo.)

A: You are right around the corner from an excellent source of information, which is the Colorado State University Extension Service. The people there can help you much better than I can from Fargo. Go to http://tinyurl.

com/5vlw3s3 to find an agent nearest you.


Q: I found your website today while searching for information about red maples.

I’d like to say it’s by far the best horticultural website I’ve come across. You have a knack of explaining people’s questions in a simple, easy to understand way. Thanks. (email reference)

A: Wow. Thanks for the compliment! This is something I will keep in my files so I can review it in my old age.


Q: I have two elm trees in my yard that are more than 100 years old. One of the trees is dripping a sap that is burning the grass. I don’t know what species of elm they are. Other than the dripping, they are both very healthy. Is the sap harmful to dog paws? (Shakopee, Minn.)

A: The sap must be raining down to actually burn the grass. This very likely is the result of heavy feeding from a dense aphid or other sap-sucking insect. It shouldn’t harm the dogs, but I would imagine that their fur and paws are a sticky mess.

You might want to consider contacting an International Society of Arboriculture certified arborist to inspect the trees for soundness and any diseases. The insect pest that is causing all the droppings also can be identified and brought under control. To locate a certified arborist, go to http://tinyurl.com/69fgll3.


Q: I found your website after running a Google search to find out what I can do for a corkscrew willow. I bought the tree about six years ago. It has grown substantially since that time. I noticed what I thought were woodpecker holes.

However, a month or so later, I noticed that those woodpecker holes were expanding in size. I was told by the local nursery that the holes were caused by bore beetles, which are common to willow trees. I used a systemic drench solution on the tree and put some tree/prune sealer on the holes. The beetles have disappeared, but I can see that the beetles were able to get almost two-thirds of the way around the trunk. The leaves are falling off, and the upper branches don’t seem to be getting enough sap through the cambium layer.

Will the cambium layer rebuild itself if I keep a sealer on it? Should I cut the trunk below the damaged area or just cut it down? I had clear sap dripping last year because of thrips. It seems like it takes many chemicals to keep this type of tree alive. (Paso Robles, Calif.)

A: Willows are good sources of thesis papers for plant pathologists, entomologists and horticulturists. There must be some other species, such as the palo verde, in your semitropical environment that can work to provide the same function. You will be opening yourself to a future of frustrations by keeping this tree around. When willows begin to have an impact on the landscape is the time everything starts to gnaw away at their qualities. See what some of the local nurseries have that you can put in place of this poor tree.


Q: I read many of the questions asked about ash trees, but none answered my question. We have an 18-year-old green seedless mountain ash that has two main trunks. Last summer, the leaves fell off the tree. This year, the tree didn’t produce any leaves. We have two other green ash trees that are fine. A tree expert could not find any diseases on the tree. He said to give it some time. In mid-June, one trunk produced leaves. However, the leaves fell off in August. We did fertilize the tree. Any suggestions or is there no hope? (email reference)

A: There is no hope, so you might as well have the tree removed. You can plant a new tree this fall, but plant a different species. This sounds like a systemic disease, such as verticillium wilt or a malady known as ash yellows. Only a lab diagnosis can determine what the pathogen is that is causing the problem.


Q: We have a Harrelson apple tree we planted two years ago. This year, it has many apples. How do we tell when the apples are ripe enough to pick? We also have a tree that is extremely old. We think it’s a yellow transparent. This tree probably was on the original farm property that later became the development we live in. What can you tell us about this apple tree? Do you have a contact we could show an apple? (email reference)

A: The taste test is the best way. If they are too tart for your taste, let them stay on the tree a couple of more weeks. Apples are climacteric fruit, which means the apples will continue to ripen even after harvesting. Generally, harvesting of Harrelson apples takes place around Sept. 25. Some folks like to wait for a couple of frosts to defoliate the tree before harvesting.

Horticulturist Larry Chaput is good at identifying apples. If you can get a sample to me, I’ll see if he is able to identify what type of apples you have.


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.

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