Research on the effects of foliar urea applications on fruit set and yield in 'Washington Navel' oranges

Low bi-uret urea treatment on 'Washington Navel' orange trees for six times application and a nontreated control was investigated to find out the effects on fruit set and yield. Low bi-uret urea (1.75%) was sprayed at 0.16 kg pure N per tree with 10 trees per treatment. Tagged leaves were counted at full bloom, small fruit, post-June abscission and at pre-harvest periods. Yield per tree was recorded at harvesting. Urea applications showed positive effects on fruit set. As far as the fruit ratio reaching the harvesting from the June abscission is concerned, application in February produced significantly better fruit set than the untreated control. Our results indicate that foliar application of low bi-uret urea in February resulted in significantly improved yield. Urea application significantly increased the amount of the fruit.