Abstracts

Dix, M.E. 1976. Protection of Great Plains shelterbelts from insects, p. 169-171. In Shelterbelts on the Great Plains. Proc. Symp. [Denver, Colo., Apr. 1976]. Great Plains Agric. Council Publ. 78, 218 p.

Trees severely damaged by insects in the shelterbelts on the Great Plains are common, and they reduce the effectiveness of the entire shelterbelt. Currently the major pest species can be divided into two categories, the borers and the defoliators. Boring insects structurally weaken, deform, or kill their hosts trees. Defoliating insects decrease crown density and retard tree growth. Most surveys identify the problem but do not estimate its importance. Better methods of assessing and predicting insect populations are needed. Presently, insecticides are used to control all the major pest species. Few alternative immediate silvicultural or biological controls are available.

Rhoads, A.F. 1976. Effects of air pollution stress on urban plantings in New Jersey. American Nurseryman 144(11): 11, 48, 50-51, 54-55.

Trees for urban plantings must be able to survive in a hostile environment. On the other hand, trees can have an ameliorative effect on the harsh city environment. Trees are able to absorb gaseous pollutants, including ozone and sulfur dioxide, and to muffle noise. However, in most urban areas, the number of trees present is not sufficient to have a significant impact on air quality, temperature or noise levels. The major contributions of most urban plantings are visual and aesthetic. This article will cover some specific effects of air pollution, one of the urban stresses, on trees in New Jersey.