Comparison between novel and traditional spray application techniques in strawberries

1. Comparison between novel and traditional spray application techniques in strawberries D. NUYTTENS, P. BRAEKMAN & D. FOQUE Institute for Agricultural and Fisheries Research (ILVO) – Technology & Food Science Unit – Agricultural Engineering Burg. Van Gansberghelaan 115, bus 1, 9820 Merelbeke (BELGIUM) Research questions • Can spray boom systems improve the spray results in a strawberry crop compared with the traditional spray gun? • What is the effect of nozzle type and setting on spray boom deposition results? Materials and Methods • Spray application techniques • Elsanta strawberry crop • Average height ± 0.40 m • Growth stage: end of fruit production • Approx. 8300 running metres ha-1 • Canopy spray deposition measurements • Mineral chelates (Fe, Co, Cu, Mn, Mo, Zn; 100 mg L-1) • Same collectors for the different applications • Analysis: Inductively Coupled Plasma (ICP) • Deposition measurements • were normalised to a concentration of 100 mg L-1 in the tank and an application rate of 1000 L ha-1 ground surface • are expressed as relative values (%) compared to the maximal feasible deposition, assuming a perfectly uniform distribution of the spray liquid on the contours of the crop canopy • Filter paper collectors (7.6 x 2.6 cm²) • Three collectors on the crop canopy → spray distribution • Two inside the crop → crop penetration • Five plants were selected as repetitions 3-nozzle vertical spray boom VMD: Volume median droplet diameter vvol50: Average droplet velocity Handheld spraygun application Results and discussion • Deposition (%) on the crop contours for the ≠ collector positions • Deposition (%) on the inside of the crop for the ≠ collector positions • Significant effect of collector position on deposition (2 > 3 > 1) • Important variability of the deposits measured at each sample point • Significant effect of collector position on deposition (4 > 5) → Deeper position in the crop • Important variability of the deposits measured at each sample point • Deposition (%) on the crop contours for the different techniques • Deposition (%) on the inside of the crop for the different techniques • Clear effect of spray system on deposition: boom ~22-60% vs. gun ~20% • Difference most pronounced on top of canopy: boom 13.1% vs. gun 4.5% • Highest deposits with ID 12002, Albuz AVI-Twin 11002 & TeeJet XR 11003, all at their recommended working pressure of 6.0, 6.0 and 2.5 bar • Deposition with gun was only significantly lower than boom for ID 12002 nozzle • Best crop penetration with the ID 12002 nozzle: big and fast droplets • Increasing spray pressure above the recommended one and spray angling did not improve penetration Conclusions • (automated) vertical spray booms are a valuable alternative for the traditional spray gun: • operator exposure↓, labor-intensity↓, spray deposition and uniformity ↑ • Nozzle choice significantly affects spray deposition and penetration • Highest depositions with the air inclusion or extended range flat fan nozzles at their recommended spray pressure Reference: Braekman P, Foqué D, Messens W, Van Labeke M-C, Pieters J G, Nuyttens D. 2010. Effect of spray application technique on spray deposition in greenhouse strawberries and tomatoes. Pest Management Science. 66(2): 203-212