Can foliar fertilizer sprays substitute granular applications?
Relatively little work has been done on foliar fertilization with nitrogen, phosphorus and potassium and many questions still remain on a few aspects of foliar fertilization. Some of the leading works have established that applications of low-biuret urea and phosphorous acid have managed to increase flowering, fruit set and fruit production. Foliar applications of potassium nitrate or mono-potassium phosphate have been found to increase the size of the fruit. However, most studies have been carried out with trees that had good nutrient levels to begin with, so that the foliar applications were complementary to normal fertilization practices. The effects of foliar applications of NPK on starved trees are not known and the long term effects of a totally foliar programme are much less known. In theory any plant can be sustained with foliar feeding but in reality it would probably not make any practical and economic sense for citrus. Biologically speaking, trees are designed to feed primar
