November 5, 2004
Q: Over the last three to four weeks, the leaves on my plum tree have started to turn yellow with some faint green color remaining. Normally they are a very deep, dark green and have red veins. The leaves are still attached to the branches, but are wilting at the stem. I don’t see anything abnormal on the trunk or branches, such as cankers or other damage. It is planted in a fairly shady location (direct sunlight varies, but probably about three to four hours a day) and is surrounded by large trees and a lilac hedge. Also, it is planted about 3 feet from the stump of a flowering crab tree. It is mulched with wood chips. Could it be lacking iron after all the recent rains or possibly from the decomposition of the crab tree? I have started giving it some Miracle-Gro every few days. Does it need chelated iron? (e-mail reference)
Q: We have three willows, two Wisconsin and one niobe golden. They are planted together in a flood plain. They have solid rock ledges about a foot and a half below the soil, which is extremely loamy clay and always wet. The roots have spread laterally a long way since they were planted. Two of the willows are fine, but one Wisconsin has yellowing leaves. The trunk seems to bulge out a foot above ground and the bark is lifting out and off for about another foot. The trunk tapers to slender below the loose bark. The bark peels off easily, is spongy and separating. The leaves of the other willow trees are bluish-green. The bad one has leaves that are olive green and distinctly yellow, but plentiful. A few smaller branches are pure green, with no yellow leaves. The leaves have been yellowish since late spring. (e-mail reference)
Q: My beautiful wine-colored hollyhocks are turning black when they flower and then die. Most of the buds are drying up and dying and the leaves are covered with brown spots and holes. Do you know what the problem is and will it affect other flowers in the bed? (e-mail reference)
Q: I know someone who is having trouble with her petunias. They are planted in black dirt mixed with compost and well-decomposed manure. Every year about the first of July the whole plant turns yellow. She puts liquid iron on them and they seem to recover. Is it possible that they need to be fertilized earlier? I told her that it would be a good idea to send in a soil sample. She plans to do so. Am I missing something? (Hettinger, N.D.)
Q: Our beautiful flowering crab tree is not looking well. It flowered beautifully this spring, but its leaves turned brown and fell off. The trunk has a split in the bark the entire length of the tree. Can it be saved? (e-mail reference)
Q: We live along the Sheyenne River. This spring we had clay fill brought in and this fall we would like to have some spruce trees transplanted and maybe some pine trees. Do spruce and pine trees do well in clay/sandy loam soil? Also, we have a shelterbelt composed of cottonwood, ash and dogwood trees. We had black fabric put down, but now I hear that isn’t good for the trees. I’m willing to take it out if it is going to harm the trees. We have had problems with the fabric blowing in the wind and rubbing against the trees. Is it wise to buy trees now and plant them or should we wait until spring? (e-mail reference)
Q: My weeping willow is at least 40 to 50 feet tall and is 30 years old. Part of the tree hangs over my neighbor’s fence. I agreed to have the limbs that hang over her yard cut. I also want to top the tree so it’s even on each side. Should I have it cut in late fall or early spring? (e-mail reference)
Q: I have a cluster of grapes on my desk that appears to have mildew, but I’m not sure. They are covered with a white powdery mold and the fruit is shriveled. Also, if I overfertilized some hydrangeas with manure, what would happen? (Forman, N.D.)
Q: We have a patch of red rhubarb that has been in the same place for years. The last couple of years the leaves start turning brown at the top and then spreads downward and the stalk gets limp. This starts happening in late June and gets worse from then on. Is there something we can do? (Wimbledon, N.D.)
Q: We would like to move some marigolds. Will the move kill them or just slow them down? (e-mail reference)
Q: Do hollyhocks and delphiniums give off a scent? (e-mail reference)
Q: I have two large dogwoods. They are about 15 to 20 feet tall and 6 to 8 inches at the base.
Two months ago I did some landscaping and put dirt around the trees to a depth of about 4 inches. My plans were to let the dirt settle and then dig out dirt from the tree back about 4 or 5 feet to form a border. This would put the soil in the 5-foot ring back to the same depth as before. I did that a few days ago, but now I am noticing that the tree has white worm-looking tentacles coming off the base. They are about a half to three-quarter inch long. When you pinch one, it crumbles like dirt. Did I leave the dirt covering on too long? (e-mail reference)
Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at firstname.lastname@example.org. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.