Weed scientists have built-in job security. University of Illinois weed scientist Aaron Hager dryly joked about his secure job during a lecture on weed resistance that he gave at a recent farm show.
The lecture room was packed. Corn and soybean growers intently listened to Hager tell them that, yes, weeds are masters of change. If you cultivate to kill them, they will delay their emergence. If you spray continuously with one product, weed escapes will develop resistance and then spread millions of seeds across your fields. In other words, you can’t beat weeds over the long term with the same strategy. Weeds will always find a way around it.
At a recent media event in Arkansas, growers demonstrated the nightmare that can develop if resistant weeds are not dealt with correctly. Flooding spread seeds from herbicide-resistant Palmer pigweed across 100,000 acres of cropland. Some growers were able to control the weeds with timely and multiple applications of products. Other growers who relied on fewer applications that were not applied on time failed. Journalists saw the results of these practices on a stop where a completely clean soybean field sat across the road from a completely weedy field.
While it is possible to control resistant weeds, it is expensive. The grower with the clean soybean field spent $80/acre to do it.
So the message from scientists like Hager needs to be heeded. You should not wait for resistant weeds to appear, because by then it is too late. Instead, diversify weed control programs now and keep your fields clean.