RESIDUE DYNAMICS OF ACEPHATE AND METHAMIDOPHOS IN URBAN DOORYARD CITRUS FOLIAGE, POMPANO-BEACH, FLORIDA - AUGUST-SEPTEMBER 1978

  • 1 January 1980
    • journal article
    • research article
    • Vol. 14  (1) , 3-6
Abstract
Residues of acephate and its toxic metabolite methamidophos, attributable to the State-Federal program for eradication of the citrus blackfly [Aleurocanthus woglumi] Ashby on citrus foliage, were assessed in urban areas in Pompano Beach, Florida. Eighteen dooryard citrus trees were sampled on 2 line transects, each about 1.6 km long, along 2 city streets. The trees were sampled twice monthly for 5 months, beginning before chemical treatments were applied, continuing through the acephate treatment period, and ending when residues decreased below the limits of detection. Acephate and methamidophos residues, as high as 302.5 ppm and 15.8 ppm, respectively, were detected on leaves within 1 day after the first of a series of 3 treatments. Significant conversion of acephate to methamidophose was observed. Of the 143 samples collected, 144 contained measurbale residues of both compounds; methamidophos accounted for an average of 19% of the total residues. Both compounds degraded rapidly, however, and residues averaged below 1 ppm approximately 4 wk after 3rd treatment in the series. Average foliar half-lives for acephate and methamidophos were 8.93 days (SD = 2.52) and 8.40 days (SD = 2.55), respectively.