One of the interesting challenges faced by organic agriculture is the
occasional dilemma arising when pesticide residues (usually
chlorinated hydrocarbons, CHCs) show up in an organically grown
I have a general request and a specific request.
The general request is for information and citations concerning which
crops (particularly horticultural crops) are known bioaccumulators of
pesticides and/or heavy metals.
The specific request is for ideas. I know of several occurrences in
which squashes and pumpkins have shown significant dieldrin residues
while the soils in which they were grown did not. The tantalizing
curiosity is that while the soils *did* contain CHC residues (mainly
DDT/DDE -- the ratio showed it was old stuff), the squashes and
pumpkins *didn't* accumulate much of anything except the dieldrin.
These crops were grown *after* dieldrin was withdrawn in 1991 (?).
Anybody know to what extent dieldrin was used as a stable spray ??
Most folks I know use a good dollop of manure for their cucurbit
hills, and if the product was used in stables *that* might be one way
for it to end up in the squash but not show up in the soil.
This one's a real head-scratcher for me, and any assistance will be
Whilst I'm feeling appreciative, thanks to Larry London et al. who
have so far sent me some good stuff on bioremediation.
Bart Hall-Beyer, ):*