Improving Herbicide Application Accuracy in South Asia¹

Abstract

In 1998, Indian regulatory agencies approved the registration of CGA 184927, MON 37500, and fenoxaprop for postemergence control of isoproturon-resistant littleseed canarygrass. Herbicides used in rice and wheat before 1998 were generally mixed with sand or urea and were applied by hand. Foliar pesticide spray applications consisted primarily of insecticides and fungicides that were applied to high-value crops. These pesticides were often sprayed to runoff with backpack sprayers that were equipped with single hollow-cone or flood nozzles. Applicators walked through the fields, swinging the wands in sweeping motions resulting in uneven pesticide distribution and overapplication. The newly registered postemergence herbicides were applied with the same equipment and in the same fashion. After these applications, control of littleseed canarygrass was strikingly inconsistent, and the growers blamed the lack of control on the manufacturers. It was later clear that basic understanding of the application techniques was lacking. In response to this, an application training workshop was organized and conducted in India and Nepal in 2000. The workshops focused on teaching the participants how to use and fabricate multiple-nozzle booms, the importance of flat-fan nozzles, calibration, drift avoidance, and applicator safety. To date, approximately 3,000 farmers, extension agents, scientists, and industry representatives have attended more than 30 workshops. The participants were unanimously enthusiastic about the value of the workshops. Although simplistic, the adoption of this technology will significantly decrease the amounts of herbicides applied and will increase efficacy and efficiency.

Assessment of occupational exposure to pesticides applied in rice fields in developing countries: a critical review

“…Typically, the use of backpack/knapsack sprayers can lead to higher levels of pesticide exposure when compared to the use of mechanical application methods such as trucks or aerial sprays in developed countries (Panuwet et al 2008;Phung et al 2012b). This is because rice farmers often walk through the fields swinging the spray wand in a sweeping motion during application activities, thus they can be intensely exposed to the spray plume (Bellinder et al 2002;Li et al 2019). There is also concern that small-scale farmers in developing countries may have high pesticide exposure due to unsafe working practices, lack of PPE, and weaker legislative protection (Da Silva et al 2016;Phung et al 2019).…”

Strengthening Farmers’ Knowledge for Better Weed Management in Developing Countries

“…Innovative channels are being used to deliver improved weed management knowledge to farmers, including primary schools in Tanzania and the herbicide supply chain in Bangladesh [17]. A series of training workshops on herbicide application techniques were organized in India and Nepal in 2000 [18]. The workshops focused on teaching the participants how to use and fabricate multiple-nozzle booms, the importance of flat-fan nozzles, calibration, drift avoidance, and applicator safety.…”

Occupational Exposure to Pesticides Applied by Rice Growers in Malaysia

“…Levels of exposure to pesticides applied with knapsack sprayers are generally higher than for mechanical spraying equipment like tractor-mounted booms and aerial sprays (Phung et al 2012). This is because individuals may walk through the field whilst moving the wand or gun in a sweeping motion and thus may have intensive exposure to the pesticide spray plume (Bellinder et al 2002;Li et al 2019). Typically, dermal exposure to pesticides whilst using knapsack sprayers is much greater than exposure via inhalation (Choi et al 2013).…”