> treating "after the bloom" doesn't really
> mean anything unless we assume that there
> is no residual imidacloprid in the tree
> from one year to another.
Maples and other deciduous trees tend to drop
blooms and pollen in late spring, and drop their
leaves in fall, so all that lasts from year to
year would be the wood and roots. Any "residual"
pesticide may not be an issue, as it would certainly
remain in the "dead" wood, but the bulk of it would
be flushed from the vascular system, as the amount
of water that moves through a tree in a month is
very impressive.
Prior experiments using dyes such as this one
may be instructive in determining the exact amount
that might exist as a second-season residual:
http://tinyurl.com/3l7xqs
or
http://www.treelink.org/joa/1999/nov/06_evidence_for_the_downward_movement.p
df
The point made by the paper cited is this:
"It appears that portions of trunk-injected
materials are transported downward into the
roots and are then transported upward in the
sapstream in the following season or seasons."
Anyone tried woodpeckers?
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