Salinity in grapevines - Time to apply post harvest leaching irrigation

Sodium Chloride toxicity - Sellicks Beach, McLaren Vale wine region.
All of these vineyards pictured are showing foliar signs of sodium chloride toxicity, more simply called salt uptake.

In these situations it is essential that salt is leached from the soil to reduce excessive build-up over seasons. Typical leaching fractions may be in the range of 10 to 20%, and are best applied prior to bud-break if soil testing shows salinity levels were not reduced sufficiently by winter rainfall.

In addition consider the use of Humic acid. Humic acid can reduce the effects of soil salinity in simple terms because it binds with sodium and prevents it being taken up by the vine.

Care of grapevines with salinity - GWRDC Factsheet.