Glyphosate-resistant crops made farming a lot easier when they first came out, but then the weeds started to catch on, too. Nowadays, herbicide-tolerant crops will only work as part of a more comprehensive, Integrated Pest Management plan.

Glyphosate (Roundup) is very effective against weeds, but you can't use it just any old way or you'll end up encouraging the development of resistant weeds. Learn to find the best timing, mix, and application method, and complementary control methods.

Rely too much on any one herbicide and you end up with weeds that will resist its effects—and that's just what is happening now with glyphosate (Roundup). See how you can increase effectiveness by diversifying your weed-management strategies.

A good herbicide will control the current population of weeds, but also create a powerful “selection pressure”: any weeds that survive its effects will go on to thrive, immune to any further applications. Learn how to keep selection pressure in check.