Technical Yearbook 2024

Salts Salinisation of vineyard soils in some of our dry cultivation regions is a general occurrence. Contrary to the expectation that brackish salts might be reduced/ leached out by the water masses caused by a river in flood, the opposite reaction is often observed. These observations are directly linked to the drainage ability of the soils rather than the quality and volume of water during the floods. Following floods, excessive salts from surrounding saline soils accumulate in poorly drained low-lying areas. The floods allow movement and accumulation of salts which would not occur in normal (dry) conditions, concentrating brackish salts in the waterlogged, poorly drained areas. On a smaller scale, this is also observed where producers effectively force brackish salts out of the root zones on the vine row using strip wetting, and in so doing concentrate these salts in the middle row and lower soil horizons. With full surface water saturation, as experienced during floods/waterlogged conditions, brackish salts can move back to the root zones, leading to local salinisation. This phenomenon, combined with anaerobic and cool soil conditions, can supress high levels of salts in the feeder roots and in extreme cases toxic salt levels can cause the vine to die.

Saline patches caused by flood waters (Worcester, December 2023).

Vines dying due to high salt levels (Worcester, December 2023).

Practical tips Although it is not possible to control the occurrence of floods, it is important to drain the excess water from vineyards as soon as possible, keeping the following tips in mind: • Ensure that drainage design and layout are done correctly for new plantings. • Ensure that drainage and storm-water infrastructure are sufficiently maintained and regularly cleaned. • Consider pumping out stagnant water if it is not possible to divert water away from vineyards. • If access roads are flooded and vineyard rows are inaccessible during the active growth period, alternative methods of applying disease control should be considered, for example using backpack sprayers. 

Reference https://www.wineland.co.za/waterlogged-conditions-in-vineyards/

For more information, contact Callie Coetzee at callie@vinpro.co.za.

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TECHNICAL YEARBOOK 2024