Spray application to tomato plants in greenhouses. Part 1: effect of walking direction

The paper reports the results of some spray application trials carried out in two tomato greenhouses to assess foliar deposition, ground losses, and dermal operator exposure when using handheld high-pressure spray lances. Two operating ways (forward vs. backwards operator movement) and two different plant vegetative stages (pre-production vs. full development) were taken into consideration.An experimental design with one factor (the operator walking direction) was adopted, arranged according to a randomised block design with three replicates. Volume application rates were settled according to the plant development: 900 L/ha in pre-production stage and 1800 L/ha at full development stage.The results showed no statistically significant differences in the mean foliar deposition between the two walking directions in both development stages. The greatest differences among the sampling locations were observed in pre-production stage, when, due to the spraying technique (spray jet directed from top to bottom), the foliar deposits in the low part of the canopy were much lower than those in the middle and high part.Also ground losses were unaffected by walking direction: they ranged on average from 14.3% to 23.5% of the applied volume rate.Finally, the dermal operator exposure was greatly affected by walking direction: at full development stage, it was 8 times higher walking forward than walking backwards. So, this simple change in field practice, can noticeably improve the operator safety, without penalising working capacity and quality of deposition.