261 ALTERNATIVE SOURCES FOR FOLIAR APPLICATION OF POTASSIUM TO APPLE TREES

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  • 1 Department of Fruit and Vegetable Science, Cornell University, Ithaca, NY 14853-0327

Potassium nitrate, potassium sulfate and potassium acetate were applied as foliar sprays at recommended rates for each material to Empire and McIntosh apple trees in a potassium deficient orchard. Five sprays of each material were applied at approximately one-week intervals beginning in mid-August All sprays were applied by means of a small air-blast sprayer calibrated to deliver 800 1 ha-1 of a 1.744X tank mix, i.e. equivalent to dilute sprays of 1400 1 ha-1. Total amounts of K applied per ha were 8.6 kg with K-acetate and 28 kg ha-1 with K-nitrate and K-sulfate. Leaf samples were collected from each plot at normal harvest date for each variety and washed prior to drying and analysis. Regression analysis indicated a significant (P=0.05) positive relationship, r = +0.4740, between total amount of K applied and leaf K regardless of the source. Significant positive relationships were found between average fruit weight and percent leaf potassium with both varieties.

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