Hot water treatment trial update

15 November, 2007

In the August/September issue of NZ Winegrower, Corbans Viticulture revealed the research they have been undertaking the past four years on the Hot Water Treatment of dormant vines and vine cuttings. The results to date are encouraging for the industry and will ensure that higher health plants are provided to the industry.

Hot water treatment (HWT) is an alternative method to chemical control for reducing fungal diseases such as Petri disease and Blackfoot in grapevines. It is used widely by nurseries and quarantine facilities in Australia, USA, Canada, parts of Europe and South Africa. In 2006, as part of their commitment to practicing sustainable viticulture, Corbans Viticulture developed HWT protocols specifically for treatment of cuttings and vines grown in New Zealand’s cooler climate. HWT vines were replanted back in the nursery to assess survival and growth. Two modified HWT protocols have been used for subsequent vineyard trials.

Trial vineyards have been established in Gisborne and Hawkes Bay. Stage II of the HWT research programme involved planting hot water treated Viognier vines at Bell Vineyard in Gisborne, and Sauvignon Blanc vines in the Mulcaster block, Ngatarawa Wines in Hawkes Bay. The vines were given HWT (using protocols developed by Dr Anna Graham at Corbans Viticulture) alongside untreated controls. Both sites were well prepared and the vines were soaked in cold water for at least three hours prior to planting to avoid dehydration.

Trials in the Mulcaster block commenced in 2006. Sauvignon Blanc vines on 3009 , SO4 and 101-14 rootstock were provided for this trial. Over 96% of these vines involved in the HWT trial have shoot growth typical or exceeding growth expected from those vines not HWT. A further trial block has been established this year and the growth and development patterns will be closely monitored.

The Bell Vineyard property has also had exceptional results . All of the 950 vines involved in the trial successfully established with the exception of only one vine.

Vine growth and health will be monitored at both trial sites over the next two years. Grape and wine quality of HWT vines will be compared with untreated vines in micro- vinification trials as part of stage III of the HWT research programme.