Winter Application of Low-biuret Urea to the Foliage of ‘Washington’ Navel Orange Increased Yield
The objective of this study was to test whether a single winter prebloom foliar application of low-biuret urea would increase the yield of 30-year-old ‘Washington’ navel orange trees [Citrus sinensis (L.) Osbeck] on Troyer citrange rootstock [C. sinensis ‘Washington’ x Poncirus trifoliata (L.) Raf.]. All trees received a winter (November to January) soil application of urea (0.5 kg N/tree). Trees were maintained under irrigation or irrigation was withheld from 1 Oct. to 1 Mar. To determine the optimal time for foliar urea application, trees in both irrigation main plots received one application of low-biuret urea in mid-November, mid-December, mid-January, or mid-February applied at a rate of 0.16 kg N/tree.