Svensson found that tipping the upper fan downward improved deposition of pesticides on the far side of the fruit trees, compared with both fans aimed horizontally. This not only gave good chemical penetration into the tree canopy, but also reduced spray drift into the atmosphere. We found the crossflow fan's downwind deposits above tree height were much less than those from conventional sprayers. The enigineers also found the spray drift from the crossflow fan didn't travel as far downwind as spray did when applied with the conventional sprayer. One problem we witnessed with conventional sprayers is that the spray cloud dodges, or goes around the tree canopy.
Some spray actually goes up and over the trees.
The crossflow design helps limit this effect. While changes in technology will ultimately help orchard and nursery managers achieve good pest control with less impact on the environment, producers must also rethink how they manage their orchards and nurseries with several factors in mind, Fox says. Today's fruits trees are less labor intensive then their ancestors, but they require more management. It's a trade-off for growers. Both researchers acknowledge that weather is the greatest variable in orchard and nursery management today.