University of Minnesota Scientist Warns: Be Careful Not to Spread Resistant Seed

In a recent Farm & Ranch Guide article, Jeff Gunsolus says that combines and equipment can carry glyphosate-tolerant weed seed to nearby fields. Curbing the spread of glyphosate-resistant weed seed through equipment is one easy step in implementing a resistance management plan.  

Different weed species have various, unique methods of dispersing, so ensuring machinery is clean when moving between fields is one step to help avoid spread. For instance, marestail (horseweed) is known to spread more easily through wind than the heavier seeds of giant or common ragweed.

What cultural practices do you follow to avoid spreading possibly resistant weeds to other fields?  Has this been a concern for you or others in your area?