> says that corn pollen doesn't really travel as far as most
> people think. He says he plants adjoining blocks of corn
> and almost all the cross-pollination is in the first two
> rows - beyond that it drops off to nothing within a few feet.
That is not quite right. Pollen, even big corn pollen, can travel a long
way. Ann mentioned 1 km. That is probably in the ballpark. But far from
the source, the pollen is dilute and tends to get swamped by the huge sea of
pollen within a corn field. It is a numbers game. The problem is worse in
seed production, since we normally plant only one row of male for each four
or six rows of female. So the sea of native pollen is not quite so thick.
In the seed production context, isolation is normally 330 feet, and unless
we are really unlucky (contaminant nicks with seed field, wind blows
strongly from that direction at flowering, or male parent timing is off),
contamination rate is well under 1%. Also, the relative sizes of the two
fields makes a difference, and seed fields tend to be fairly small. I have
some old references on pollen travel if you are interested.
The big issue is what will the tolerance be for GMO kernels in non-GMO grain
(or seed) bound for Europe. Suppose regulators use PCR to check for
characteristic GMO DNA in grain. PCR is so sensitive that you could
probably pick up contamination at the rate of 1 kernel in 10,000. It is
impossible to avoid GMO contamination at that level. Fortunately, European
law governing GMO allows for trace contamination.
I have heard that a tolerance of 1% or so is expected for GMO seeds in
non-GMO seed. I don't know about grain, but it would be silly to have a
more stringent tolerance for grain than for seed. If tolerances on that
order are accepted, they won't be hard to meet.
I think it is a matter of time before people get used to the idea of GMO's
and stop worrying about it so much. Nevertheless, the grain/seed industries
have to listen to what the customers want.
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