Stan, I'm not disputing the longevity of the residues in the soil in any
way!  I'm here for discussion--not to hold a postition!

I've seen that data (perhaps compliments of you some years ago).  As I
recall, the residues remain much longer in heavy clay soil.

Allen, your point is well taken, and perhaps "half life" was the wrong term
to use.  The point is that neonics tend to bind tightly to the soil
particles, and are to the best of my knowledge, not then readily absorbed
by plants.  If this were not the case, we should be seeing considerable
leaching into groundwater and year-by-year buildup in plants to the extent
that further application would no longer be needed.

So here would be the empirical test:  have any of you seen any groundwater
tests, or good data on constantly elevating levels in plants?  Some recent
data that I've seen for canola does not suggest buildup after many years of
use.  But perhaps it occurs in the heavy clay in Stan's area.

Anyone have good data?
-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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