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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have what I believe is an amur maple that is about five years old. I just noticed that the tree has a hole in the trunk. The hole is about 3 inches long and an inch or so wide. I saw something inside the hole and dug it out, but it fell in the snow and I couldn't find it again. It looked like a grayish-white oval bug. This hole goes about halfway through the trunk. Last summer, the tree did fine. However, I cannot imagine a hole this deep is good for it. Is this tree a goner? (e-mail reference)

A: A hole that goes straight into a tree probably is the work of a woodpecker or sapsucker. My bet is that the insect found the hole and took refuge in it. I would suggest getting some Tanglefoot and pack it into the hole up to and around the surrounding trunk of the tree. This will keep any more insects from moving in and keep the woodpeckers away. Woodpeckers don’t relish getting their beaks and feet all covered with this sticky material. I think your tree is OK and should recover.

Q: I've had my jade plant for about six years. About a month ago, the leaves seemed dusty, so I dampened a paper towel and lightly dusted it. Now the leaves are dying. I was just trying to help it and don't know what to do. I hope you have some advice. (e-mail reference)

A: This doesn't bode well for your plant. The dampened paper towel may have had some chemicals in it that turned out to be toxic to the foliage. I doubt this will kill the plant. The plant should drop all its leaves and then during the next six to eight weeks should start to releaf again. The next time you are motivated to dust it, put it in the shower and spray the foliage with tepid water.

Q: I have a large black walnut tree in my backyard. According to my neighbors, this tree is about 60 years old. During the early summer, the tree is extremely messy. It drops what I assume are the flowering bodies, which stain everything black. The tree also is filled with aphids every year, which adds to the mess. During the fall, we often have to pick up 20 or more 5-gallon pails of walnuts. The squirrels hide the rest. With all of this, I still hate to cut it down. However, the tree has started losing bark and creaks terribly in the winter during our numerous times of high winds. Everyone claims this tree is valuable for its wood if I can find someone who could use it. Any suggestions? (e-mail reference)

A: Black walnut is highly valued for use in wood products. What lumber people want is a straight trunk with no branches for as many feet as possible to give the wood the appearance of being knot-free. Check around to see if there is anyone who will pay you to harvest the tree. Also, you may want to put an advertisement on the Web and in your local paper. Since this is bound to attract all kinds of characters, make sure the person cutting the tree down is a certified arborist, has insurance and is experienced in removing trees. I think local lumber and furniture stores that are independently owned would be the best bet as contacts to harvest your tree.

Q: My Christmas cactus will bloom and then get a second set of buds, but they do not open. Why won’t the second set of buds open up, and why do the branches go limp? (e-mail reference)

A: There are a number of possibilities. The plant may have insufficient energy to open a second set of buds. Blooming is an energy-consuming process. Another possibility is dry indoor air or the buds may not be getting enough water. The plant may have a vascular disease that is plugging the water-conducting tissues. This would explain why some of the branches are going limp.

Q: I live in Argentina and have a plum orchard. We have had a problem for the last four or five years, but nobody can tell me what the problem is. About a month or two before harvest, the plums turn yellow. After that, the plums turn brown or black and fall off the trees. This is a major problem. Can you help me? (e-mail reference)

A: The trees have plum pox virus, which is a devastating disease to stone fruits. Go to for a Penn State University publication that appears to be the best diagnostic and prevention advice that I can find for you. Good luck!

Q: I bought an orange tree in 2004 in Kansas but moved to Fort Lauderdale in 2005. The tree always has produced fruit. Can the fruit be eaten? I never have tried to because it did not say you could on the tag. This year, there are so many oranges. Are there orange plants that you can’t eat the fruit? (e-mail reference)

A: If the fruit tastes good, enjoy it. If not, spit it out and don’t eat it. Some orange trees sold as ornamental novelties are inedible, while others are tasty. Either way, just a taste won’t hurt you.

Q: I just bought my first home that has a great display of yellow tulips. They are the first to bloom in our neighborhood by at least two weeks. I think part of the reason is because of the southerly direction the bed faces. It also may be because the bed is covered in ivy. I hate all this ivy and I want to tear it out next year. Will this cause my tulips to bloom later? Will taking out the ivy leave the tulips too exposed to the elements? Will tearing out the ancient ivy disrupt the bulbs? Another question: My mother always holds onto the bulbs she gets from indoor potted bulbs and replants them in her garden. She trims off the buds the first year so they can rebuild their energy. Is this the correct thing to do? Right now, my basement is full of bulbs from all the potted plants I've purchased during the last year. I just don't know what to do with them, so I've foolishly left them far too long. (e-mail reference)

A: The ivy should be pulled up in winter while it is still dormant. This will cut down on the biomass you would be facing in the spring and summer. Allow the tulips to bloom as normal and the foliage to die. After that, dig up the ones you want to save for replanting and discard the rest. Your mom’s tactic of removing the bud is a very frugal one. Does she also hide money under her mattress? What she is doing won’t hurt anything but isn’t necessary unless the bulbs are undersized when planted. As for your saved bulbs, get them into the ground as soon as possible after sorting out the seconds or diseased bulbs. Altering the environment by taking out the ivy undoubtedly will alter the blooming time somewhat. Your premise is correct that it is the south-facing environment that is stimulating the bulbs to bloom earlier.

Q: I planted petunias at a commercial property in a very large bed at the entrance to a building. The plants looked great, but then began to stop blooming. We fertilized on a regular basis (every two weeks) with fish emulsion. I also adjusted the water because the plants were being watered too much. Shortly after correcting the water issue, we had a very cold spell. A few weeks later, we had two below-freezing nights, but we covered the plants before the freeze. The plants are not rebounding as well as I had hoped. One small section has leaves that are yellow. It's been two weeks since the freeze. What are your suggestions? With the exception of a few plants with yellow leaves, the plants look healthy. Should I add iron or use more fertilizer? The temperatures are back to normal for us, which are the upper 60s by day and 40s by night. (Phoenix, Ariz.)

A: Petunias are high-heat and sunlight plants, so they are not going to rebound until the temperatures get more into that category. They will limp along until you start having temperatures in the mid- to upper 80s on a consistent basis. The cold, wet soil contributed to the yellowing of the foliage. When the temperatures begin to kick up a bit more consistently, give them a shot of water-soluble fertilizer with iron. Fertilizing now during the cool temperatures you describe is not going to do any good.

Q: I grew two sweet potato vines in pots this past summer. When I dug out the plants, one had two tubers. Can these be propagated? How do I start a plant for outdoor use this summer? (e-mail reference)

A: Take the sweet potato tubers and lay them on a bed of pasteurized potting soil. Barely cover them with some of the same soil. With watering and heat, they should sprout after a short time. From these growing vines, you can propagate the vines using some cuttings. This all happens quickly, so I would suggest that you begin this operation sometime in mid- to late March or early April for outdoor planting.

Q: Last December, I received a blooming Christmas cactus. How do I care for it? We live in Casa Grande, Ariz., for the winter, but will be going back to Rapid City, S.D., in the spring. How much and how often do I water? Do I mist it? How often and what kind of fertilizer do I use? (e-mail reference)

A: Lucky you, basking in Arizona this winter! Christmas cactus plants are easy to care for. The best thing I can tell you is to go to my website at, where I have answered hundreds of questions on this particular plant. After reading through everything, get back to me if you still have questions.

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 - Jan. 12, 2011

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