Repeated field applications of selected insecticides to seed lettuce satisfactorily controlled infestations of the lettuce seed stem aphid, Macrosiphum barri Essig. These treatments also gave a very significant reduction of an infestation by the two-spotted spider mite (Tetranychus telarius (L.)), but they did not give an adequate reduction of lettuce mosaic. A tree fold increase in yield of lettuce seed was obtained by the use of repeated applications of parathion sprays and dusts for control of the lettuce seed stem aphid. This increased yield was significantly higher than that obtained fro111plots treated with other materials, and was judged to be economically satisfactory. There was also a very significant increase in the weight and size of the lettuce seeds. This was also confirmed by cage tests. This aphid caused a reduction of about 66% in yield of lettuce seed obtained from untreated plots. It was possible to demonstrate that these stem aphids caused a lettuce seed loss of as much as 59%, when artificially infested plants were grown in field cages. However, the exact degree of infestation necessary to produce economic loss of seed was not established. The feeding of this aphid also produced a significant redaction in the number of normal seedlings. In addition, there was a decrease in the mean emergence period of the aphid-damaged seeds, indicating a more rapid germination. A significant increase in damage to cotyledons of the seedlings was obtained from thc aphid-damaged seeds, which showed that this aphid is one cause of "red cotyledon" of lettuce seedlings.
Document Type: Research Article
Publication date: June 1, 1959
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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.