This idea of using dark cultivations to control weeds which are stimulated
by light into germination is not a new one. Hartmann and Nezdal (1990)
Naturwissenschaften 77, 158-163 reported very similar results to those you
describe from the USDA author.
The idea is based on the principal that the phytochrome system, which is
responsible for many germination responses, will not be stimulated if
cultivations are completed in the dark because of the absence of red
There is a possible problem with the idea though. There are several weedy
species which produce seeds which do not require red light in order to
germinate. If dark cultivations were employed for any length of time the
tendancy would be select for those species and populations and you could
with a worse weed problem than you started with!