Chemical analyses of untreated samples of turnip greens, mustard greens, spinach, kale and collards gave relatively high values for apparent parathion, especially in fall crops. When these crops were treated with multiple applications of parathion at the rate of one-half pound per acre, and were grown under actual or simulated commercial practices, the residue tolerance of 1 p.p.m. was not exceeded on spring crops of turnip greens and mustard greens 10 days after the final application or on spring crops of kale, collards, and spinach at 7 days. The data indicate that fall crops of turnip greens and mustard greens would not exceed the residue tolerance at 14 days, while fall crops of kale, collards and spinach were well within the residue tolerance at 10 days. Parathion apparently accumulated in turnip greens, but not in spinach, with each weekly application, resulting in higher residue levels at 10 and 14 days after the final application in plots receiving multiple applications than in plots treated once. Residue levels in spinach increased approximately in proportion to dosage. Spray volume had no appreciable effect on residue levels in spinach or turnip greens. Sparse plant stands or mineral oil as an adjunct increased initial residue levels in these crops, but differences were insignificant 10 days after the final application.
Document Type: Research Article
Publication date: April 1, 1963
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