Effect of NaCl on cold hardiness of Malus spp. and Syringa vulgaris

In early winter, NaCl was applied to branch surfaces of Malus sp. cv. Radiant and Syringa vulgaris L. growing in gardens and along salted highways. Hardiness of twigs collected from November to February was determined by damage to xylem, cambium, and bud apical meristems after exposure to test temperatures between 4 and −45 °C. In January and February, twigs receiving NaCl either from controlled applications or from highway deicing salts lost hardiness while NaCl-free twigs remained hardy. In both locations the loss in hardiness corresponded in time and amount to the increase in twig Cl and Na.