Pickett, A.D. 1960 Effects of disease and insect control practices on biological balance in apple orchards.. Biological and Chemical Control of Plant and Animal Pests. American Association for the Advancement of Science (Publication No. 61) Washington, D.C. 273 pp.

Notes: [A symposium presented by Section O on agriculture at the Indianapolis meeting of the American Association for the Advancement of Science, December 28-30, 1957.] Lepidosaphes ulmi is normally controlled by a parasitic chalcid, Aphytis mytilaspidis and a predacious mite, Hemisarcoptes malus in Nova Scotia. One experiment mentioned in this review investigates the effect of fungicide treatments on this scale and its two important natural control agents.