Rose of sharon illness - Knowledgebase Question

Lemont, Il
Question by ajawelp
March 19, 2011
Last year my rose of sharon were infected by some illness. Their leaves became very thick and dwarf. Flowers never opened in full bloom. Only partially . I asked about several peaple at various garden centers but they did not know. i wonder if they will recover and grow as ussually this year or this is something that demaged the bushes permanently. Only one side of the garden got sick.

Answer from NGA
March 19, 2011


It's really difficult to diagnose a plant problem without actually seeing the plant and the damage, which is probably why no one has been able to help you at the garden centers. I think rather than a disease, your Rose of Sharon was attacked by insects. Some insects with sucking mouthparts (aphids, thrips, etc.) can remove enough of the fluids within the leaf tissues to cause the leaves to become thick and malformed. They can also leave behind some disease pathogens which can be carried throughout the plant. My suggestion is to prune your Rose of Sharon back to remove any overwintering insect eggs and to watch it carefully as it leafs out this spring. It may be that the problem was due to a combination of weather conditions, water stress, and an overly large population of insects last year and that you won't have a similar problem this year.

If you notice the leaves are damaged as they unfurl, the problem is within the stems of the plant. If damage shows up after the leaves unfurl, the problem is with insect feeding. If you watch your plant closely, inspecting it on a daily basis when the new leaves begin to grow, you should be able to determine whether the problem is a disease or an insect infestation. The best solution is to take a sample of the damaged leaves and flower buds into your local cooperative extension office for positive identification of the problem. Helpful staff can inspect the plant parts under a microscope to rule out or confirm insect or disease problems. Take your plant samples to University of Illinois Extension North Suburban Cook Office, Third District Court Building, 2121 W. Euclid Avenue, Suite 251, Rolling Meadows, IL 60008 or phone them at (847) 818-2901 to find a Master Gardener Diagnostic Clinic in your neighborhood. Best wishes with your Rose of Sharon.

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