Marlborough

has been saved from the previous season (or taking a gamble that the vine will push a sucker after the trunk has been cut). The retained sucker is trained to become the new vine trunk. As the vine still has it’s original root system, the sucker growth is very strong and the vine is usually back into production the following season (one season’s crop is missed, following making the trunk cut). Full production is likely within 2 – 3 seasons of “amputating the trunk. This method has been tried on a number of vineyards around Marlborough with reasonable success, at least initially. We don’t yet know how long the re-trunked vines will last and there is also potentially some difficulty in determining where the GTD infection has spread to within the old trunk. While GTD infected wood can show a dark stain or area of dead wood within the trunk, research has also shown that seemingly healthy wood below the point of visible infection may also be infected. The best advice so far seems to be to cut as low as possible below the point of infection but above the graft union. And if re-trunking fails, the vine can be replaced as described earlier.

Prevention is always better than cure though, and the best recommendations for preventing or at least delaying the onset and / or spread of GTD is following some simple rules: Protect pruning wounds using a registered product, avoid pruning in or shortly after rain, clean your pruning tools after pruning infected vines, remove dead and dying vines completely from your vineyard area and avoid making large pruning cuts into old wood. Simple rules yes. Easy to follow consistently? That’s up to you.