Use-pattern considerations

Standard error bar shown about mean of three replications representing a composite of 10 soil samples/rep./sample period. 

Compound A to Compound B were made to a mature wheat canopy while six sequential applications of a formulation with a 1 1 ratio of Compound A to Compound B were applied to mature apple trees. These studies closely mimicked actual agrochemical use patterns in terms of application rate and timing, application volume, irrigation, and other key agricultural practices. 

When applied to wheat. Compound A was readily detected in soil samples collected beneath the treated canopy. Compound B was detected only sporadically in soil. Due in part to a greater application volume (1000 vs 300 Lha water) and a higher application rate for Compound B, both compounds were more consistently detected in soil following application to apple foliage. It is often difficult to establish dissipation kinetics under these conditions because as residues in the soil dissipate, additional compound may continue to be deposited on the soil, resulting in a complex, variable dissipation pattern. As a result, it is not always practical or advisable to study soil dissipation in the presence of a crop. 

For compounds applied to annual crops, another approach is to apply the compound to bare soil prior to crop emergence and follow the soil dissipation of the compound as the crop emerges and grows throughout its normal growing season.This is the appropriate use pattern for pre-emergence compounds and represents another approach that may used to study the soil dissipation of foliar-applied compounds. 

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Rochford J, Grant 1, LaVigne G (1977) Medical students and drugs Further neuropsychological and use pattern considerations. Int J Addict 12 1057-1065... 

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