Questions on: Cranberries
Ron Smith, Horticulturist, NDSU Extension Service
Q: What can I expect as far as the life expectancy of a highbush cranberry shrub? (Moorhead, Minn.)
A: It possibly will live longer than you, but with indifferent cultural care and bad weather, as short as a year. Most people end up pulling them out and replanting with something else after 15 to 20 years because they want a change of scenery!
Q: When is the best time of the year to cut cranberry bushes back? (Linton, N.D.)
A: I am sure you mean the American cranberry bush viburnum. The best time is early spring, before leaf-out, if flowering and fruiting are not important for that season. Otherwise, do it right after blooming.
Q: When is the best time of year to prune back cranberry shrubs we planted around our deck? They are getting out of hand. (E-mail reference)
A: I assume you mean the cranberry bush viburnum. It can be pruned in the spring before new growth begins. If you prune out a third of the branches, and repeat that each year, you will have the benefit of the flowers and berries. If you give the plants a hard cut back in the spring, literally right down to the ground, you will lose the flowers that year.
Q: I was wondering what is wrong with my cranberry bushes (2 years old). I started with four and have only two left. The leaves seem to curl. I have sprayed them with daconil, but it hasn't really helped. They are on the north (somewhat northeast) side of the house and under a roof so they don't get much sunlight. (Walhalla, N.D.)
A: The curling leaves are caused by aphids feeding. Daconil is a fungicide and is ineffective against aphids. I suggest spraying your viburnums with Orthene now and early next spring as the leaves unfold. It is both a contact and systemic insecticide, so you should get effective control.
Q: Enclosed are two samples from 2-year-old old dwarf European cranberry bushes,
Viburnum opulus, `Nanum.' Parts of the bushes look really healthy but all three plants
have these deformed leaves. What is it and what can I do to get rid of it? Also, what
fertilizer should I use?
A: The deformed leaves are brought about by aphid activity. To control, spray with an insecticide like Sevin or Orthene.
Viburnums and other woody plants seldom need fertilization. When they do, I suggestabout a half pint per shrub of 5-10-5 or something similar.
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