Effect of fluorine level in Valencia orange leaves on yield and fruit quality

A 19-year-old Valencia orange grove was used in a 5-year fluoride spray experiment to determine the effect of different levels of fluorine in the leaves on yield and quality of fruit. Four concentrations of fluoride sprays were applied during 3 different periods of time each year. The levels of fluorine in the spring flush leaves each year were correlated with yield of fruit. Significant yield reduction was caused by exposure of the trees to fluoride during the spring bloom period. Application of fluoride sprays after the middle of May resulted in buildup of fluorine in the leaves but had no effect on yield of the trees. Critical levels of leaf fluorine are presented.