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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have a Santa Rosa plum and butterfly bush. Last summer, both of the bushes had curly leaves. Any idea why this happened? (Ben Lomond, Calif.)

A: This could be due to insects feeding on the underside of the leaves or a disease. I suggest getting in touch with a University of California Extension agent where you live. Go to to find an agent near you.

Q: I have had my tree for more than 20 years. This is the first time I have had a major problem with it. My tree has sticky leaves and they are falling off. It has been in the same pot for more than five years. A horticulturist in Atlanta suggested I trim back the roots growing out of the bottom of the pot and spray it with a combination of mild dish soap and alcohol. I did that, but the leaves are still falling off. When I trimmed the roots, I found that the roots had broken through the saucer underneath the pot and had grown in a spiral in the carpet and even through the carpet into the flooring! It now has a new saucer underneath. It used to be next to an indoor rose bush. I moved the rose bush outdoors when it started to die. Now is it is in the yard and doing fine. I did see a few cottonlike small circles under a few of the leaves. However, it mostly is sticky or shiny material on the leaves. I have had this plant for a long time and do not want it to die. (e-mail reference)

A: This sounds like evidence of spider mite activity. These arthropods are the size of a period at the end of this sentence, so they are difficult to see with the naked eye. Generally, there is a fine webbing between the leaves. The other possibilities are San Jose or cottony cushion scale. Go back to your local horticulturist and ask for a systemic insecticide to eliminate this problem. The insecticide is applied to the base of the plant. It is absorbed and moved through the plant. This will kill the insects as they feed.

Q: I have a tall cactus that I would love to cut some branch lines off and replant it in another pot. Is this going to work? If so, how should I do the cutting? (e-mail reference)

A: Cut off the parts that you want to propagate and allow the cut ends to callus for a few days. Then stick them in a sandy soil mix to get them to root. Treat them as you would your parent cactus by not overwatering. There should be evidence of new root growth in six to eight weeks.

Q: I found something weird in some tomatoes I bought at the store. When I sliced one of them, I looked at the seeds and saw that they were sprouting. It was one of the tomatoes on the vine in the store. I am curious about why this happened. (e-mail reference)

A: This is not unusual but also not common. The tomato was overripe and ready to propagate itself. My bet is that it didn’t taste very great, either.

Q: We have a tall Norway spruce in our front yard. It’s a great tree, but during the last couple of months, it has been shedding newer growth. We were told it was squirrels, but we haven’t seen much squirrel activity in the tree. Could the tree just be old? I would really like to keep the tree if possible. (e-mail reference)

A: It takes just an army of one red squirrel to do the damage. I don’t know why squirrels pick on a particular tree unless it has something to do with their brains telling them to gnaw on something. Try to distract the squirrel with some corn or peanuts in a shell. Squirrels love that stuff, so they will give up working on your tree to savor the good taste of the peanuts or corn. If or when you observe the furry friend eating the peanuts or corn, you can set a live trap and do whatever you wish from that point on.

Q: I came across your name while searching for possible causes for the bad condition of my blue spruce trees. I am hoping you can help determine what may be wrong. I noticed this summer and fall that one of my trees is much sparser on the backside (facing west). The other three trees also are not as full but not as bad. The trees don't get any sun on the west side due to heavily wooded trees near the spruce trees. I suspect needle cast disease is the problem and have attached some photos for you to look at. Thank you in advance for any insight you may have. (e-mail reference)

A: I could not detect from your photos whether this is a disease of any kind. However, evergreens don’t thrive under deciduous tree canopies. I would encourage you to contact a Michigan State University Extension agent in your area to get a better diagnosis.

Q: Our Santa Rosa plum tree fruited this season. There are about 100 green plums on the leafless tree. Should I pull them off? (e-mail reference)

A: Yes, remove them. They will not mature in time for consumption and will be an energy drain on the tree.

Q: I have had a cactus plant for 10 years. Recently, it has started collapsing at the base. It has had a soft-looking, yellowish-brown base for more than five years. At first, I thought this was the normal result of trying to grow a desert plant in Iowa. I've attached two pictures with the hopes that you might be able to assist in recommending a way of mending the condition. Any recommendations would be appreciated. (e-mail reference)

A: The problem could be due to mealybug activity. However, I couldn’t see any problem from your photos. Carefully knock the plant out of its container to see if there is something feeding on the roots. I am at the edge of my expertise on this, so I’m unsure what could cause this discoloration and collapse. The ball on top looks good, so there is no disease migration taking place. Sorry I can’t be more helpful than this.

Q: I have investigated all over the place trying to find a way to save my aphid-infested hibiscus but have not come across a solution that I really want to try on my poor plant. I read your column and saw that you have some very creative ideas and a lot of knowledge about hibiscus plants. I have two hibiscus plants that I keep outside during the summer but bring them in during September or October. I live on the southern edge of zone 6. Before I bring the plants inside, I spray them twice with a pesticide (five days apart). This year, I did not spray them. Within two weeks, aphids coated them. In October, I took them outside and sprayed them twice (three days apart) with Garden Safe Houseplant and Garden Insect Killer. I brought them inside and the bugs stayed away for a little while but then came back. Reluctantly, I sprayed them twice inside the house. However, the bugs just keep coming back. The spray only seems to keep the insects at bay for a week maximum. I really don't want to keep dousing them with chemicals because I prefer to use organic methods. However, I will try anything to kill the aphids. I tried cold shocking them in 30-degree weather for half an hour. Should I try a longer period of keeping the plants cold? I also pruned them extensively. I had hoped that all of the bugs were off the plants, but that didn’t work. What should I do? (e-mail reference)

A: Talk about being creative! You have tried every reasonable trick except for repotting with pasteurized soil. Get everything set up for the repotting by getting some fresh soil, clean containers and insecticidal soap. Knock the plants out of the containers and shake off as much of the soil as possible without damaging the roots. After that, dip the plant in a bucket of insecticidal soap up to where the roots just begin. Repot and water in well. This should take care of these pests. If they show up again, then there is another plant somewhere in your house that is the carrier. Remember, it only takes one aphid to have a population explosion. Their growth is exponential, so their population doubles with each generation. In just a few days, the number can be in the thousands, so check the plants carefully. If needed, use a magnifying glass to make sure there are no aphids hiding on the branches.

Q: I stumbled across the NDSU Extension Service website while trying to research what is wrong with my apple tree. I've can't find anything that describes what's wrong, so I'm starting to wonder if it's multiple diseases or pests. I moved into my house more than three years ago. The first summer, my apple tree bore amazing fruit. It bore less fruit the next year, so I decided it was time to try some light pruning. Last year and this year, the tree produced even less fruit. Everything comes in great in the spring but then the leaves curl. There isn't any sort of powdery mildew on the tree. After the leaves curl, the apples start to fall off. This fall, the top of the tree looked dead, while the bottom of the tree had normal fall colors. Could you please tell me what the problem is with my tree? Can I fix it or do I need to take it down? Thank you so much! (Lehi, Utah)

A: The symptoms you describe could be from multiple causes, such as bark beetles boring into the trunk or branches, root rot, stem cankers or a possible vascular disease. Usually, when these symptoms go from bad to worse like you describe, apple trees won’t recover. I think you would be better off taking the tree out and starting new, but don’t plant in the same location! If it is a root rot or other soil-borne disease, doing so would be certain death for the new planting.

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 e-mail

NDSU Agriculture Communication

Source:Ron Smith, (701) 231-7123,
Editor:Rich Mattern, (701) 231-6136,
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