Field Tests with the Systemic Insecticides Thimet and Bayer 19639 as Cottonseed Treatments in 19571

Abstract

Thimet at 1 pound and Bayer 19639 at 1, 1.5, and 2 pounds per acre applied to reginned cottonseed reduced the stand of cotton significantly below that obtained from untreated seed. Thimet at 1pound per acre did not reduce the stand when applied to acid- or f1ame-delinted seed. When Thimet-treated seed was planted in the drills in which a previous such planting was made, severe phytotoxicity occurred. Plants recovered but fruiting was delayed. However, yields were not reduced because conditions were favorable for plants to set fruit later in the season. The seed treatments gave thrips control for 4 weeks after plant emergence. Thimet at 1 pound per acre held cotton f1cahopper infestations below injurious levels 4 weeks after plant emergence when applied to reginned seed but not when applied to acid-delinted seed. Thimet was slightly more effective than Bayer 19639 against this pest.