The Challenges of Specialty Crop Weed Control, Future Directions

Abstract

The process of labeling new herbicides for specialty crops has always been difficult. Progress in solving specialty crop weed control problems will likely be more challenging in the future. Major crops like corn, cotton, rice, soybean, and wheat are planted on millions of hectares, and most of these crops are treated with herbicides. In contrast, specialty crops (i.e., minor crops, e.g., container ornamentals or lettuce) are planted on 122,000 ha or less; thus, the potential value of herbicide sales is limited in these crops by the low number of hectares planted per crop. High crop value, small hectarage per crop, and generally marginal herbicide selectivity results in a high potential of liability for herbicide registrants and little incentive to label herbicides in these crops. The Interregional Project Number 4 (IR-4) program facilitates the registrations of pesticides on minor crops. Work needed to support pesticide tolerance in a given crop is conducted by IR-4 and cooperators. However, to develop new crop tolerances, the IR-4 process requires new herbicides. The success of glyphosate-resistant soybean has resulted in a less profitable herbicide market for all crops. In response, most primary pesticide manufacturers have reduced the size, or even eliminated herbicide discovery programs. As private industry slows or stops herbicide development, there will be fewer new minor-crop herbicides. Many questions face minor-crop weed scientists. For example, what are other practical solutions to control weeds in minor crops besides herbicides? Should research focus on development of competition models and decision thresholds or on weed removal tools such as robotics? What funding sources are available for minor-crop weed scientists? Are grant programs at the Federal level prepared to increase support for minor-crop weed research? Will university administrators replace retiring specialty crop weed scientists, knowing that their funding sources will produce little overhead? These questions require a response from all parties interested in specialty crop weed control.Nomenclature: Corn, Zea mays L., cotton, Gossypium hirsutum L., lettuce, Lactuca sativa L., rice, Oryza sativa L., soybean, Glycine max (L.) Merr.; wheat, Triticum aestivum L.