This work aimed to study herbicide spray distribution uniformity of a shielded lateral boom, in the rows of perennial tree crops, using combinations of nozzle tips, operated at small distance from the target. A computer software program was developed to simulate the overlapping of the spray pattern from the nozzles positioned in the shielded boom portion and at the end of the boom. After computer selection of nozzle tip combinations (coefficients of variation lower than 10%), some combinations were studied under field conditions, using a systemic herbicide (glyphosate) and a contact herbicide (paraquat) application. The results indicated that the software could be a powerful tool in nozzle tip combination selection. The most efficient tip combinations for both herbicides studied (glyphosate and paraquat) at reduced spray volume (100 L ha-1) were: a) TT110015 nozzle tips spaced 52.5 cm, combined with the tip TK-0.5 at the boom extremity (50 cm from the last nozzle), ground speed of 5 km h-1, 15 psi (103 kPa) working pressure, with the distance of the last boom nozzle of 20 cm from the tree trunk; b) SMCE-2 nozzle tips spaced 15 cm combined with the tip TK-0.5 at the boom extremity (20 cm from the last nozzle), with ground speed of 4 km h-1, 60 psi (414 kPa) working pressure, with the distance of the last boom nozzle of 30 cm from the tree trunk; and c) TLX-2 nozzle tips spaced 15 cm combined with the tip TK-0.5 at the boom extremity (20 cm from the last nozzle), with ground speed of 5 km h-1, 60 psi (414 kPa) working pressure, with the distance of the last boom nozzle of 30 cm from the tree trunk. The sprayer speed of 5 km h-1 showed better weed control compared to 4 km h-1.
spray nozzle; spray boom; nozzle spacing; spray simulation; shielded boom
