An organosilicone surfactant (L‐77) and Na alginate were evaluated as adjuvants in urea sprays foliar‐applied in spring to prune treesPrunus domesticaL. cv. d'Agen which had received a maintenance soil application in winter of 300 g N/tree. L‐77 (0.03% v/v) enhanced leaf wetting and reduced spray surface tensions to levels at which sprays could infiltrate stomata spontaneously, but 75 g N/tree foliar‐applied as 4 × 0.5% urea/ L‐77 sprays failed to increase leaf N concn or fruit yield. This was attributed to the low N application rate as 450 g soil‐applied N/tree increased both parameters and as 400 g N/tree foliar‐applied post‐harvest with L‐77 increased leaf N concn by 15%. Na alginate (0.02% w/v) did not alter the physical properties of the sprays and failed to enhance spray effectiveness.