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ARS Home » Research » Publications at this Location » Publication #60601
Title: EFFECT OF SIMULATED RAINFALL ON EFFICACY AND LEACHING OF FENAMIPHOS.

Author
item Johnson, Alva
item Wauchope, Robert - Don
item SUMNER, DONALD - UNIVERSITY OF GEORGIA

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: There is increasing concern in the United Stated about the movement of pesticides in soil, groundwater contamination, and pesticide residue in food. The degradation, movement, and efficacy of granular and liquid formulations of fenamiphos in the soil and residue in squash following different simulated rainfall treatments after nematicide application were determined in a 2-year study. Rainfall treatments of 2.5 and 5.0 cm water applied one day after fenamiphos application had no effect on fenamiphos concentrations in any soil depth, or concentration of fenamiphos sulfoxide and total fenamiphos in the 15-30 cm soil layer. Root-gall indices were not affected by formulations of fenamiphos or rainfall treatments. Concentration of total fenamiphos residue in squash was far below the tolerances established for fenamiphos on other vegetable crops. Data from this experiment may be used to caution against retreatment of fenamiphos by growers who may think that 2.5 - 5.0 cm of rainfall 1 day after application may leach fenamiphos from the site needed for maximum nematode control.

Technical Abstract: The degradation, movement, and efficacy of fenamiphos (3 SC and 15 G) in the soil and residue in squash following different simulated rainfall treatments after nematicide application were determined in a 2-year study. Fenamiphos treatments were broadcast (6.7 kg a.i./ha) over plots and incorporated into the top 15-cm soil layer immediately before planting Dixie Hybrid squash. Rainfall treatments of 0, 2.5, and 5.0 cm water were applied 1 day after fenamiphos application. Soil samples from 0-8, 8-15, and 15-30 cm soil depths 1 day after the simulated rainfall applications were analyzed for fenamiphos, fenamiphos sulfoxide (FSO), and fenamiphos sulfone (FSO2). Squash was analyzed for total fenamiphos residue. Rainfall treatments had no effect on fenamiphos concentrations in any soil depth, or concentration of FSO and total fenamiphos residue in the 15-30 cm soil layer. Greater concentrations of fenamiphos in the 0-8 cm soil layer occurred following application of 3 SC than 15 G formulation. Root-gall indices were larger from untreated than most fenamiphos- treated plots, but were not affected by formulations of fenamiphos or rainfall treatments. Concentrations of total residue in squash ranged from 1 to 4 ug FSO2/g, which were far below the tolerances established for fenamiphos on other vegetable crops.