Once again, several companies and individual salespeople are guaranteeing herbicide performance. This is not an acceptable practice and has likely caused growers more problems than it has resolved. It is reasonable and appropriate to expect companies to stand behind products, however the guarantee programs have caused growers to have unrealistic expectations. Importantly, the guarantees also have lessened the likelihood that growers will use acceptable alternative management strategies. When a guarantee program is sold, growers frequently fail to accept their responsibilities for assuring adequate control of weeds.

The resprays that result from these guarantees also potentially create problems. Typically, the resprays are delayed due to the time of processing the complaint. This delay can result in some yield loss due to weed interference. Further, the crop and weeds continue to grow; the crop may be larger than described by the herbicide label and thus more susceptible to injury. Weeds may be too large for effective control, thus creating further harvest problems. Last, the resprays are likely to include an ALS inhibitor herbicide. If an ALS inhibitor herbicide was applied initially, the two ALS inhibitor herbicides may interact to cause significant crop injury and also selection for ALS resistant weeds increases.

Companies that guarantee herbicide performance are, in essence, guaranteeing the weather. The performance envisioned by growers as a result of these guarantees is economically restrictive, biologically impossible, and environmentally inappropriate. Effective weed management programs are the result of judicious use of herbicide, cultural, and mechanical strategies. Iowa State University does not feel that herbicide performance guarantees are appropriate.