Preventing problems associated with herbicide drift

Monday, April 7, 2014

Acreage planted to herbicide-sensitive specialty crops, like grapes and vegetables, is on the rise in Missouri according to the U.S. Census of Agriculture. This trend is contrasted with the recent development and debate over new herbicide-resistant varieties of corn and soybeans, which if planted in Missouri could lead to increased usage of growth regulator herbicides to which grape and vegetable crops are especially sensitive. Given the current and impending situation with herbicide usage, specialty crop production, and the potential for herbicide drift to cause injury to specialty crops, both row-crop farmers and specialty crop growers should consider ways to prevent problems that may arise from herbicide drift.

The movement of crop protection materials away from their intended target, otherwise known as "drift," poses several potential problems. For farmers who use herbicides, the consequences of drift are wasted production inputs and less effective weed control, which lead to higher production costs and lower crop yields. Drift can also pose other problems for herbicide-applicators, including legal complications that may occur if the drift from a chemical application causes damage to other people or their property. For producers who grow herbicide-sensitive crops, such as grapes and vegetables, herbicide injury can cause significant or complete financial loss from lost crop production. Most herbicide-sensitive specialty crops require intensive management and have the potential to produce high revenue per acre; this fact intensifies growers concern regarding injury caused by herbicide drift.

In order to avoid potential financial loss, conflict, and legal complications that arise from herbicide drift, both herbicide applicators and specialty crop growers should take preventive action. For herbicide applicators, drift-prevention includes having an acute awareness of environmental conditions at the location and time of application. Applicators should be aware of herbicide-sensitive crops growing near the treatment area. They should also be cognizant of wind speed, wind direction, temperature, and relative humidity, which affect the occurrence and extent of drift. Furthermore, applicators should be conscious of their spray equipment. Boom-height, nozzle type, spray angle, volume, pressure, and groundspeed all play a role in reducing drift. The label of the herbicide product provides guidance on sprayer calibration. Additionally, the MU Extension guide, "Controlling Drift of Crop Protection Materials," is a great reference for applicators regarding drift. The guide is available online or at your local MU Extension Center.

Like herbicide applicators, growers of herbicide-sensitive crops also have opportunities to take preventive action against drift. The most important step growers can take is to communicate with neighboring farmers, custom-applicators, and county roadside spray crews who service the area. Growers should provide these individuals and entities with notice of the location(s) and type(s) of crop(s) they are growing. Providing maps and a letter written in a respectful tone should help to prevent damage, and, in the future, documentation of the notice may help the grower to substantiate a complaint or recover damages. Additionally, growers may consider planting windbreaks and/or incorporating buffers between herbicide and non-herbicide treated growing areas. If the grower is in a pre-establishment phase of production, consideration should be given to the location of the growing site and the likelihood of drift problems.

More information on herbicide selection, herbicide injury, and recommendations for preventing drift problems is available by contacting MU Extension.