Foliar sprays dry quickly when applied at high temperatures, reducing absorption of the nutrients in solution.
High light intensities can improve foliar uptake.
High humidity favours nutrient uptake through the leaves in two ways; by decreasing the rate of drying of the applied nutrient solutions, and by causing the cuticle to absorb water from the atmosphere and swell, which results in the formation of more polar pores.
pH of the Spray Solution
The pH of the spray solution can influence solubility, uptake and penetration of the plant nutrients.
Wetting agents improve foliar uptake by enhancing leaf coverage. Surfactants reduce the surface tension of the solution, overcoming cuticular barriers and improving foliar uptake.
Aging leaves develop thick cuticles that hinder foliar uptake.
Young developing leaves have thin cuticles and are therefore more efficient at foliar uptake.
Higher spray volumes result in more uniform coverage and more effective foliar feeding.
Foliar applications should wet the entire canopy, especially the new leaves.
As the concentration of the foliar spray increases, uptake also increases.
Lower spray water volumes generally result in less uniform spray coverage and less effective foliar feeding.
Ambient and spray water temperatures can interact with these factors.