As the nozzle orifice wears, the spray rate increases. This causes most growers to apply more spray then intended. Once a nozzle output exceeds 10 percent of its designed rate, it should be replaced. This rate may be found in the nozzle manufacturer's catalog. Use larger nozzle sizes rather than more nozzles to obtain the additional output in the upper zone.
Larger nozzles produce larger droplets, which are desirable for tree tops.
Recommended proportioning of spray material. Spray distribution in the orchard should then be checked with water and dye. The addition of hydrated lime to the spray water leaves a traceable residue to help determine coverage. Check to see that spray material reaches the tops of the trees but is not excessive. Then examine the lower tree skirts and inside the tree canopy for coverage.