A novel, air-assisted tunnel sprayer for vineyards: optimization of operational parameters and first assessment in the field

Tunnel (recycling) sprayers have long been recognised as an important tool to reduce drift losses. Depending on the crop and the growth stage, tunnel sprayers may recycle up to 60% of the spray volume, thus enabling the farmers to control pests even at reduced PPP dose rates. However, the introduction of tunnel sprayers in Italian vine-growing farms has been hindered so far by high machine cost, low working speed, and often unsatisfactory uniformity of deposition, generally related to the difficulty of correctly managing the air currents inside the tunnel. Recently, a new prototype, air-assisted shielded sprayer has been developed by the University of Udine and Agricolmeccanica s.r.l. The two-row, tractor-mounted sprayer uses a lamellae separator wall, placed in front of each nozzle boom, to recover the excess spray which has not deposited on the canopy. Initial tests have been conducted to analyse the effects of the main sprayer settings (air flow rate, distance between the shields, and orientation of the air outlets) on spray recovery. Maximum recovery rate was 95.1% under static conditions. The sprayer was then used for spray application in the vineyard during the 2007 season, showing high reliability and work capacity. The recovery rate was 34% to 77% under field conditions, depending on the leaf area of the crop and other factors.