An evaluation was made during midsummer 1972 to measure damage by the carpenterworm, Prionoxystus robiniae, and the ash borer, Podosesia syringae, to green ash in windbreaks in North Dakota. Intensity of infestation was determined in four land resource areas and four age classes of windbreaks. Of the 96 windbreaks examined Statewide, the ash borer was present in 51 percent and the carpenterworm in 28.1 percent. The carpenterworm predominated in trees older than 16 years, and the ash borer was more prevalent in trees under 15 years old. Damage by borers was greatest in the southwestern quarter of North Dakota where the carpenterworm had attacked 23.4 percent of the trees and the ash borer 7.2 percent. Damage by borers was negligible in the remainder of the State. The carpenterworm can be considered a minor problem in the eastern half of North Dakota. However, the presence of the ash borer in more than half the windbreaks sampled Statewide makes this insect a potential threat to their management. Control measures are available and should be applied where owners are concerned.
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