Submitted to: Transactions of the ASAE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/11/1999
Publication Date: N/A
Citation: Interpretive Summary: Since the 1950's, grape growers have predominately applied pesticides using low volume, air-assist sprayers. Most vineyard sprayer designs were adapted from those used to treat tree fruit. By making concentrated applications, field efficiency was increased because fewer refill operations were required. However, these air-assist sprayers generally produce significant amounts of spray drift and other off-target deposits. Over-the-row, hooded sprayer designs can match the crop canopy and provide superior spray distribution compared to conventional, air-assist sprayer treatments. Spray containment by a hooded boom system can also reduce off-target spray movement. This work is among the first of its kind that looks at the application process in terms of the application efficiency and efficacy as well as the health and safety of the equipment operator. This work is also unique because it examines the biological efficacy of applications as well as coverage and deposition factors that influence pest control in grapes. The results of this work are important because they show that, while all application techniques evaluated deposited some pesticide on the equipment operator, the hooded treatment significantly reduced operator exposure to pesticides compared to the conventional application technique. Disease evaluations showed that the hooded sprayer treatments used in this study were able to provide equivalent or better control than the conventional, air-assist treatment by providing more desirable spray deposit characteristics. These results, combined with previous work that showed that the hooded sprayer system reduces drift, show that this form of application has many beneficial characteristics for the equipment operator, vineyard owner, and local community.
Technical Abstract: The effects of air-assisted delivery and spray deposit characteristics, disease management and worker exposure were evaluated in a commercial vineyard using a crop with a characteristically light to medium density canopy. Neutron activation techniques were used to quantify amounts of fungicide on the leaf samples and on driver clothing. Spray quality characteristics were evaluated using a computer imaging system. Conventional applications were made using an air-assist sprayer with centrifugal fans. A tunnel or hooded sprayer was used to make non-air- assisted applications at two application rates. The performance of the hooded sprayer treatments was equivalent to or superior to the conventional sprayer. Performance evaluations included foliar and clothing spray deposits, foliar spray coverage, and foliar disease ratings. Results are that under similar crop conditions, the hooded sprayer can reduce worker contamination and spray drift while providing equivalent control of vineyard diseases compared to the conventional, air-assist sprayer.