Winter rye (Secale cereale) is the darling of the cover crops and for good reasons. Getting established in the fall is almost fail-safe, winterkill is nearly impossible, and it is the first to green up in the spring. Below is a picture of winter rye in sugarbeets seeded in 22-inch rows last fall. The winter rye was terminated with glyphosate after the sugarbeets had emerged.
Two things warrant caution in this picture. First, the sprayer kicked up enough dirt that some of the glyphosate was inactivated, allowing the winter rye in the wheel tracks to survive. This is nothing new or surprising. The surviving rye plants are in the boot stage and heading soon. If not terminated in the next week or two, grainfill will be well underway, and the chances that viable seed is produced increase exponentially.
One of the major weeds in the Central Great Plains and Pacific Northwest is feral rye. Feral rye (Secale cereale) is nothing more than cultivated winter rye that has established itself permanently as a weed in fields. Cross-pollination combined with directional selection has allowed for the selection of genotypes that can maintain an in-field population year after year. The directional selection was provided by the cropping system (continuous wheat or wheat-fallow). One of the traits gained by the feral winter rye is extended dormancy.
There is nothing to say that something similar can not happen in this region, even if we are not in a continuous wheat or wheat-fallow cropping system. Mother Nature generally finds a way when given the opportunity. Winter rye is a cross-pollinating species and there is plenty of genetic diversity in the VNS rye you buy to meet your cover crop needs.
Make sure you terminate this winter rye and minimize if not completely eliminate, the chances of genetic recombination that would create an opportunity for the winter rye to go feral.
Source : umn.edu