Yield responses by sultanas to applications of zinc and superphosphate

Abstract

Zinc foliage sprays increased the yield of dried fruit of sultana vines on two light-textured alkaline soils in the Mildura area. Neither vineyard exhibited zinc deficiency symptoms. Yield increases with zinc application were mainly due to better setting. The increase occurred in the season of application. Depressed yields with superphosphate were obtained in three years out of seven, after 19 years of heavy annual dressings on one of these sites. The application of zinc to canes during the dormant season offset this decrease but had no effect on vines not receiving superphosphate. Seasonal variations in the responses to zinc treatment are discussed.