Can we approach complete dependence on foliar-applied urea nitrogen in an early-maturing peach?

The suspected contributory role of soil fertilization to nitrate pollution of groundwater has encouraged exploration of novel fertilizer management st rategies. Foliar-applied urea has long been used to supplement soil N appli cations, but there have been no apparent attempts to replace soil N applica tions completely in deciduous orchard culture. Two experiments mere conduct ed to study the effect of foliar-applied low biuret urea on productivity an d fruit growth of the early maturing peach [Prunus persica L. Batsch(Peach Group)] cultivar, Early Maycrest. In a 3-year experiment, a total foliar ur ea regime was compared to an equivalent amount of N applied to the soil. Th e foliar treatment supplied adequate amounts of N to the various organs of the tree including the roots, shoots, and fruit buds, but mean fruit weight s were Io vr;er than in the soil-fertilized treatment. In a a-year experime nt, a 50 %-50 % combination treatment of soil-applied N in late summer with foliar-applied N in October, maintained yields and fruit Weight equal to t he soil-fertilized control. Some soil-applied N appears necessary for optim um fruit growth. Soil N application may be needed to support root prolifera tion and associated processes, but we did not determine a threshold amount of soil-applied N needed. The combination treatment also reduced excessive vegetative growth which is characteristic of early maturing peach cultivars . Therefore, this combination treatment offers promise as a viable commerci al practice for maintaining tree productivity and controlling excessive veg etative growth in peach trees.