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Published August 20, 2010, 12:00 AM

Too much shade, fertilizer could harm plant

Q: I have two variegated weigelas. They were blooming when I bought them three years ago. However, they have not bloomed since. Any idea why?

By: Don Kinzler, INFORUM

Q: I have two variegated weigelas. They were blooming when I bought them three years ago. However, they have not bloomed since. Any idea why? (Battle Lake, Minn.)

A: There should have been some blooming. It could be the plants are in too much shade or too much nitrogen fertilizer was used. Weigelas bloom best on new growth, so do an annual spring pruning. However, you can do it now because your plants have not bloomed. This should give you a flush of flowers next year. If that doesn’t work, pull the plant out because life is too short to wait for a plant to get around to producing flowers.


Q: I have two apple trees with branches that die every year. It starts in the spring when these branches leaf out later than the others. The leaves that do grow on the affected branches are small. During the course of the summer, the leaves dry up and the branch dies. I cut the tree back significantly, and the branches that grew the following year seemed to do well, but then the problem came back. I mark the bad branches in late summer and then cut them out. I thought it was fire blight, but the branches do not have the shepherd’s hook or the dark, burned color. The branches that are not affected have apples on them.

What is the problem or do I need to take the tree out? Will it affect the other apple tree I planted this year in a different part of the yard? (Williams, Minn.)

A: I cannot determine what is wrong with this tree. It seems to resemble borer or canker problems, but I cannot tell. I would suggest you get in touch with the extension office in your county. Go to www.extension.umn.edu/offices to see if an agent or a master gardener in your county can pay a visit to see what problem exists with your tree.


Q: I have hosta plants that have faded and wilted hamps. Some are blooming, but it depends on the plant’s orientation to the sun. Should I cut the problem plants at the base and hope for a second blooming, or should I leave them wilting on the plant? The way they look is not very attractive, and I also am afraid that the dead blooms are taking some strength away from the plant. Thank you in advance for your help and advice. (e-mail reference)

A: I assume your term “hamps” refers to seed pods or spent flowers. Yes, go ahead and cut them back to improve the aesthetics of the plants.


Q: We have a mature raspberry patch that is giving me a bumper crop. However, after picking the berries, I noticed little white worms coming out of the fruit. Yuck! What are they? Are the worms harmful for us to eat, and is there any way to get rid of them without using pesticides? (Seattle)

A: Unfortunately, what your plants have are raspberry fruit worm larvae. They are the result of earlier activity by the adult beetle that damages the foliage.They eat the leaf tissue and leave the veins behind. The female lays her eggs in the fruit buds.

How to get rid of them without using pesticides is almost impossible other than some fanatical sanitation on your part by cleaning up the foliage and canes every year. Monitor the plants to see if the beetles show up as the foliage is unfolding. Check around in the garden centers of your community to see if they have a pheromone trap or some other way to eliminate this pest. You also might want to contact the fruit specialist at the Washington Extension Service. Go to http://ext.wsu.edu/locations/countyMap.html. North Dakota winters are severe enough that we generally don’t have to worry about this pest.


Q: We planted some decorative corn on a patch of land that was a cow yard for 100 years but was planted to grass 14 years ago. The corn is very tall and looks healthy. However, many of the stalks have tassels but did not develop ears. Some of the seed was purchased from a seed company, and some was shelled from ears we bought at a grocery store last year. The field corn in our area looks good due to timely rains and lots of heat. We are in east-central Minnesota. Any ideas? (e-mail reference)

A: This is happening way too much this year. You are about the fourth person who has told me of this problem. It is hitting my garden as well. With my own garden, I’m certain the problem is overcrowding, but other factors can cause this as well, according to the NDSU corn breeder. The major culprit seems to be the weather we’ve had this year. However, I wish I knew why the field corn is doing OK but the sweet corn is not.


Q: I was wondering if I can pick chokecherries that are green and then ripen them. I don’t want the birds to get them before I do. Will they ripen? (e-mail reference)

A: I wish they did ripen off the tree, but they don’t. You will have to do battle with the birds for the ripe ones.


Q: I planted concord grapes this year, and they are growing well. However, I noticed a few spots of white fungus on the leaves. I am not sure what product to use to get rid of the problem. I have read that sulfur-based products cannot be used on concord grapes, but I can’t seem to find a recommendation for the correct spray. The vines get direct sun, and the soil is a sandy loam that has good drainage. (e-mail reference)

A: Following the discovery and use of a Bordeaux mixture, several relatively insoluble copper compounds or fixed coppers were developed. Fixed-copper formulations release less copper ions and are less injurious to plant tissues (safer to use) than a Bordeaux mixture. However, the use of copper compounds or fixed coppers is limited because of their potential to injure plants and lack of compatibility with other pesticides. Some of the more common commercial formulations of fixed copper include C-O-C-S, Kocide 101, Tribasic copper sulfate, Champ and Tenn-Copp 5E. There are several fixed-copper fungicides registered for use on small fruit. Try it on a limited part of the plant first before spraying the entire vine.


Q: I purchased a bag of Burpee wildflowers. I was going to spread them in an abandoned yard but started to think there may be noxious weeds in the mix. What a mess I would create if there were some weeds mixed in. What are your thoughts on this? I don’t want to screw up the neighborhood by planting weeds. (e-mail reference)

A: Wildflower seeds from reputable companies, such as Burpee, Northrup King or Ferry-Morse, will not have noxious weeds in the mix. The contents of the bag should be on the label. Read it to see what you will be getting and then you can Google the flowers to see what they will look like when they start blooming.

Most wildflower mixes I have experimented with have annuals to give a flush of color the first growing season. Some will reseed every year, and some will not.

The package will have some perennials and biennials that take a year to get established before getting around to flowering, so the complexity of the flower show will change through the years. The plants that are hardy to your area will become dominant but still have an attractive mix of colors. I’ve never been disappointed with any wildflower mixes I have planted at the NDSU Research Extension Centers or in my backyard.


Q: I’ve enjoyed reading your columns and listening to you on the “Hear It Now” radio program. This year, we have had so many false blossoms on our zucchini plants. Someone told me this could be because there are no bees in the area to pollinate the blossoms. We also are using a new garden space. Could either of these be the reason for our problem? (e-mail reference)

A: You could be right, or it could be that the plant only is producing male flowers. Examine the flowers to see if there are any female blossoms. Female blossoms are distinct enough for an amateur to identify them. If this is the case, then get a male flower and dust it with the pollen of the female. That should result in another zucchini for you. Thank you for being a faithful listener to the “Hear It Now” program.


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 ronald.smith@ndsu.edu.

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