Evaluation of the Activity of Some Diphenyl Compounds on Winter Eggs of the Fruit Tree Red Spider

Abstract

FOR several years some red spider ovicides have appeared on the market. Most of these compounds are active chiefly on the summer eggs, and far less active on the winter eggs of the fruit tree red spider Metatetranychus ulmi Koch. One of these compounds, 2,4,5,4′-tetrachlorodiphenyl sulphone (tetradifon), shows extremely high ovicidal and larvicidal activity on Tetranychids, but is not active on the winter eggs of Metatetranychus ulmi. In the course of investigation of the past five years a large number of diphenyl compounds has been tested on tetranychids¹. Some of them have been examined for activity on the winter eggs and compared with some other compounds. The latter experiments are reported here.