While no plant counts were done in May 1999, you can see that there was a virtual mat of weeds on the cultivated side, while there were few weeds in the standing stubble. The predominant weeds in the field this spring were stink weed and shepherd's purse. He indicated that while some winter annual weeds prefer no tillage, others thrive on soil disturbance. With that in mind then, working stubble in the fall to control these two weeds will not be very effective. Applying 2,4-D in late fall continues to be a more effective method for reducing their numbers.
Tillage can also stimulate weed growth if the field has been direct seeded for a few years.
Tillage removes weed seeds from the surface and plants them. If you go ahead and work the field anyway, be prepared to control the winter annuals early. While moisture conservation wasn't a big concern for much of Saskatchewan this past spring, there have been many springs when we've wanted to save every drop of moisture. Leaving the winter annuals until just before seeding may be costly in terms of lost moisture and nutrients. It's estimated that for every 10 days a winter annual is allowed to grow in the spring, it can remove one inch of moisture from the soil.