Abstract
In a replicated trial in a K-deficient area in a Fresno County Thompson Seedless vineyard, vine responses were compared to annual light (0.2 kg K per vine), to single heavy (1.0 kg K per vine) applications of K2SO4, KCl, and KNO3, and to repeated applications of a KNO3 foliar spray. Evaluations made annually for 5 years were based on chemical analyses of petioles collected during bloomtime and on visual grading of the vines for leaf symptoms of K deficiency in midsummer. The severity of foliar symptoms of K deficiency varied markedly from year to year. All treatments except the KNO3 foliar spray improved vine grades significantly over those of the untreated control. Tissue levels of K were lowest for the control and for the foliar spray treatments, highest for the heavy-rate K fertilizers, and intermediate for the annual treatments. Higher, though not damaging, levels of chloride resulted from both the single heavy and the annual light applications of KCl.
- Accepted September 1976.
- Published online January 1976
- Copyright 1976 by the American Society for Enology and Viticulture
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