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Published September 26, 2008, 12:00 AM

Rhubarb, like peonies, often outlive the gardener

Q: I have a rhubarb patch that I have done nothing with the last eight years. I dug it up, mixed together top soil and mostly cow manure and put the plant back in the same spot. Reading some of the information on rhubarb, I now realize I probably should have split it up, but it has not spread at all during the eight years. It has produced many more stalks this year, but they are dry and somewhat hollow. Is the plant too old? (Bancroft, Ontario)

Q: I have a rhubarb patch that I have done nothing with the last eight years. I dug it up, mixed together top soil and mostly cow manure and put the plant back in the same spot. Reading some of the information on rhubarb, I now realize I probably should have split it up, but it has not spread at all during the eight years. It has produced many more stalks this year, but they are dry and somewhat hollow. Is the plant too old? (Bancroft, Ontario)

A: It probably would have benefited from being divided. As for the hollow stems, they are naturally somewhat hollow, but anything in excess would indicate a problem with being too dry or too old. Rhubarb plantings are a lot like peonies. If planted the right way and in the right location, they often outlive the gardener.

Q: I have a question about my apple tree. The tree had a heavy fruit set this year, but the fruit has been falling off the tree the last three to four weeks. Approximately three-fourths of the apples have fallen from the tree. Do you have any idea why? The tree was hit by hail in early July, but the apples that are falling do not appear damaged. I’d appreciate any information you can offer. (Fargo, N.D.)

A: I’m sorry, but I don’t know why your tree would be dropping so many apples at this time of year. Generally, apple trees drop fruit early in the season if an excess set takes place. This often is called June fruit drop. Something is causing an abscission layer to form at the apple stems, which is causing them to fall off the tree. This could be due to a nutrient imbalance of some kind or a shift in the weather that is causing this problem. If the tree is healthy and vigorous, I don’t think you have anything to worry about except to keep up with the apple drop.

Q: We are having root problems caused by a poplar tree. The roots are destroying the garage foundation. My husband is attempting to dig to the roots to destroy them. How deep do the roots grow and how much do they spread? The tree is 50-plus years old. (e-mail reference)

A: This is like asking me how deep the water is in a lake! Poplar roots go deep and wide, but that depends on various factors, such as soil type, water table or climate. The deep roots are not the problem. It is the surface roots that are competing for air, water and nutrients that are a problem. If he can get the roots that are down a couple of feet or so, that would be adequate. You might want to consider the value of keeping the tree or replacing it with another species. A poplar that old is bound to have some hazard problems. You should have it checked out by an International Society of Arboriculture certified arborist.

Q: A good friend of mine took some cuttings from her plant, rooted them and gave them to me. She said it was from a begonia plant that belonged to her late grandmother. The plant does not produce flowers, but I’m not sure if it is supposed to. The plant has large leaves that are red underneath and green on top. It looks like only half a leaf. If this is a begonia, what type is it? Also, tiny flying insects have made their home in the soil and around my house! They have chewed on the leaves and have caused many of the leaves to die. They became so bad that I had to bring this beautiful plant outside. It died two days later. I still have some of the insects flying around the house. My friend could give me another plant, but I am very reluctant because of the insects. Just so you know, I have 14 other plants in my home, but these insects did not bother with them at all. What do you think? (e-mail reference)

A: It could be a Rex begonia, but that is just a guess from what you told me. As to the insects, I have no idea what they are! When planting, always start with clean plant material and use a sterile or pasteurized media. If the insects should show up again, get after them right away with an insecticidal soap or some other low-toxicity insecticide.

Q: I bought a jade plant at a fruit stand. It is in a hanging basket and has long legs hanging down. I am wondering if this is normal. I don’t think it got enough light based on reading some of your answers to questions about jade plants. I also think I need to prune it, but there are no lateral stalks or a trunk to this plant. Should I waste my time with this thing? I think it looks nice the way it is right now, but I don’t want unhealthy plants mixed in with my healthy plants. Thanks. (e-mail reference)

A: Those are aerial roots you are seeing, which are not a problem. Apparently, the plant was kept in a very hospitable environment to develop these roots. It is not a sign of poor health at all, so keep it!

Q: I happened to stumble across your Web site while looking for information on a tree problem we are having. We have a big tree just off our back patio. I’m not sure what kind of tree it is, but I did attach some pictures. It was beautiful, but many of the branches seem dead and it has seemed to retain its seeds for a very long time this year. For the first time all year, we are seeing some nice leaves sprout, but it is September. We did have a new patio put in last year that goes very near its base, but no closer than the old patio. I am wondering if that could have any impact or if we are seeing the end of this tree. Is there anything we can do to help it? Any help or advice you could offer would be greatly appreciated. (e-mail reference)

A: It is a green ash, but it is in decline. This is a result of unintended construction damage that happened when the new patio was built. The major damage was done by soil compaction around the roots, which reduces the air in the soil that is necessary for survival. The tree still might be able to be saved. Contact an International Society of Arboriculture certified arborist who is good at diagnosing problems, not just good at removing trees. Perhaps with soil aeration and some fertilization, the situation can be turned around. However, once the tree starts showing this kind of stress symptoms, it may be difficult to save it. Make sure that someone doesn’t take your money for a treatment that won’t do any good, so be sure to check the arborist’s credentials and license.

Q: What kind of fertilizer can I use on Colorado blue spruce trees? I just planted them this spring. Can I fertilize now? (Manchester, S.D.)

A: Save your money. They do not need fertilization at this time. If you really think they should be fertilized, do so next spring as new growth is starting.

Q: I have a well-established apple tree that sits in the middle of a small flower garden. My husband did some landscaping around the tree this summer. This fall, we plan to dig up the flowers and haul in a foot of dirt because I want a raised flowerbed. How will this affect the apple tree? (Redfield, S.D.)

A: A foot of soil over the root system definitely will affect the health and stability of the tree. That much dirt very likely will end up killing the tree. If you must backfill over the roots, use a sandy loam and add no more than is necessary. Also, do not put the backfill soil right up to the tree’s trunk. Leave 6 inches clear around the trunk.

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