NDSU Extension - Ramsey County


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June 20, 2011 Horticulture Column


It seems I get more busy each week but am going to take a vacation this week and do a little fishing.  I can still be reached by phone if you call the office.  I will be available to look at different things in the evenings.  Our gardens are sure looking tremendous.  The cooler temperatures are what makes most of our garden plants and flowers thrive.  The trees also have brilliant color of green also making the area very attractive for those driving by.  I have been getting many phone calls about the subject included in today’s  column.  It is too late to consider any control measures as mentioned in the article however you can be armed next spring with a application of a tree and shrub systemic insecticide.  This product should be applied in the spring and the tree does the work for you.

Gall Insects in Trees Common

            Galls are easy to find on trees around the home now. Galls are created by many different arthropods including aphids, pysllids (jumping plant lice), cynipid wasps, cecidomyiid gall midges and eriophyid mites. The gall is like a “house” for the developing arthropod larva. Larvae feed and secrete toxic chemicals within the plant tissues and the plant reacts by creating abnormal plant growth called galls. Although galls are not attractive, they generally do not cause significant plant mortality. Their injury is only aesthetic and chemical control is usually not necessary. There are several biological control agents, such as parasitoids that are common on galls and some can provide up to 50% mortality of galls. Shown are photos of common galls in North Dakota:  hackberry nipplegall caused by a psyllid and maple bladdergall mite caused by an eriophyid mite.



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