Field studies were conducted in Oregon in an attempt to determine if a relationship existed between clover root curculio (Sitona hispidula (Fabr.)) injury to the roots of alsike clover and the incidence of pathogenic fungi. Soil insecticide treatments of aldrin, heptachlor, and DDT were applied during the spring of 1957. During the autumns of 1958 and 1959 seed yields were obtained and roots were sampled and rated for the incidence and severity of both insect injury and disease. There were no differences in seed yields between treated and untreated plots in 1958, but in 1959, all treatments resulted in significantly increased yields over the untreated plots. All the treated plots showed less larval injury of the roots during 1958, and all except those treated with DDT during 1959. There was also a corresponding significant reduction of vascular root decay in aldrin-treated plots during 1958, and in aldrin- and heptachlor-treated plots during 1959. During both years some diseased plants showed 110 insect injury and, conversely, some healthy plants had been injured by inscets. The fungi most frequently isolated from diseased roots were Fusariurn oxysporurn Schl. sensu Snyd. and Han., Verticillium albo-alrurn Reinke & Berth., and an undescribed species of Phoma All three species are pathogenic to alsike clover, but only species of Fusariurn are known to be assisted in host penetration by insect wounds.
Document Type: Research Article
Publication date: June 1, 1961
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.