In extremely toxic conditions, chloride accumulates at the leaf margins and kills the tissue via dehydration. Once the vine is showing chloride leaf burn, the vines and soil are in very serious condition. Sodium is much more difficult to understand. It has been reported that sodium has limited negative effect on the leaves, however, this is unknown. The effect of sodium on the soil is well documented and it is very negative.
Sodium can kill the soil.
Soil or water with a SAR above 4 is trouble. If the SAR is above 7, grapes should not be grown. Texas vineyards have been planted at sites with irrigation water sodium levels of SAR 16, SAR 20 and SAR 43. In each of these vineyards, the sodium was so high that it killed the soil. Therefore, it is absolutely essential to have the soil and water salinity measured before a vineyard site is purchased or selected for grapes.