Vol. 15—1961 - NorthEastern Weed Science Society

147.
Residual herbicide activity was most pronounced with simazine.
Dosages above 3 lbs./A. provided seasonal control of weeds. Even
with slmazine, however, there was considerable loss of activity in
a sandy loam soil. One year after a second annual application of
simazine at 3 lbs./A., less than 0.25 lbs./A. was detected in the
upper 4 n of soil and none was detected at depths of 4-8 n • With EPl'G
most of the phytotoxic residue was found at depths below 4". The
residues were somewhat less than those required to injure most woody
plants. This and other evidence suggests that normal dosages of these
herbicides, applied as needed, will not result in the accumulation of
residues toxic to future plantings of species with tolerances similar
to those treated.
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