Temporal Dynamics of Chlorothalonil Residues on Peanut Foliage and the Influence of Weather Factors and Plant Growth

The persistence of chlorothalonil residues on foliage of peanut (Arachis hypogaea) cultivar Florigiant was evaluated under field conditions. Chlorothalonil (Bravo 720) was applied at 1.26 kg a.i./ha with a boom sprayer. The results of seven trials over 3 yr yielded an average decay rate of -0.051 μg/cm 2 per day, with values ranging from -0.093 to -0.036. This corresponds to a mean half-life of 13.6 days, with values ranging from 7 to 19 days. Decay rates increased with increasing rainfall. No influence of temperature on decay rates could be detected. A simulation model was developed to examine the effects of new leaf emergence on the measurement of residue dynamics (.)