Replanting - Protecting your investment

22 September, 2009

One of the most important vineyard management and cashflow decisions a grape grower faces is whether or not to replant an existing vineyard. This could mean a different variety, rootstock, or training system, or a combination of these changes. Should it be done incrementally to minimise lost production or undertaken in one go? And should the vines be under planted or totally removed? Understandably, many growers are apprehensive about making such a major decision that will, in the short-term, affect their bottom line.

So why would you replant your vineyard?

Economics. The current economic climate has generated considerable unrest for growers and wineries. As the industry hunkers down for the time-being, vineyards are engaging in replanting activity only. There is unease in the longevity of grape supply contracts, varietal demand and monetary tightening. The recession provides an opportunity for growers to get their vineyards operating at full capacity.

Older is not always better. As vines age, the cost to prune, manage and tend to the vines will increase. And what about mechanisation or improvements in vineyard management practises? Over the years new technology has enabled cost savings in vineyard management practises such as pruning/cane removal. Older vines and trellising systems do not necessarily accommodate new technology.

Rootstock suitability. Only recently has EMI ( Electro-Magnetic Induction) survey technology been introduced to the NZ wine industry to accurately identify the suitability of rootstocks to different soil profiles within a block. Traditionally, most rootstock selections have been based on what the next door neighbour has selected. Far from accurate as I’m sure you would agree.

Vineyard management practises can be improved through the utilisation of tools, such as EMI surveys to enable your vineyard to perform to it’s best capacity.

Total plant removal or under planting?

In cases where planting densities, row width and/or irrigation have been uneconomical, total vineyard renovation will be necessary. This enables the soil to be worked properly and hard pans that have established over time to be broken up. However, the loss of production has to be considered and gradual replanting over a number of years will ensure minimal loss of production and income.

Alternatively, to combat a loss of production, existing vineyards can be under planted with new vines whilst the old vines are cropped for another season. However, under planting does have its disadvantages.

Firstly, the young vine has multiple sources of competition including water, nutrition and light. Under planting also promotes a large degree of variability in the vineyard - plants of different ages, varieties and clones which poses vineyard management challenges at vintage.

The removal of the old vine can upset the root structure of the young vine. For this reason old vines are cut above ground level and herbicide is applied to the remaining stump. However, this brings its own potential problems as the total root system remains in the ground serving as a host and source for soil-borne and root pathogens.

Make the establishment of the new vines top priority and adjust vineyard management to favour the establishment of the newly planted vines.

Whatever planting strategy is used, the most flexibility is available when planning starts early. Only then will it become an opportunity for improvement rather then a desperate attempt to rescue an uneconomical vineyard.