If you are looking to get grafter Nigel Stead to undertake some top grafting on your vines this year, you are out of luck. And going by the forward interest, if you want to undertake top grafting next year, then you had better be in quick, as 50 percent of his time in 2017 is already booked out.
This very specialized skill is becoming more popular as growers look to change varietals, without having to wait for three years for full crops. Stead says the grafting takes place between October and December each year. That first season the vine grows new canes, which are pruned and laid down the following winter. Eighteen months after the grafting the vines are producing full crops.
So what does it involve?
"We take the head of the vine out, cutting it off just below, leaving the trunk. We put a cut in each side and place a two bud scion in each of those cuts. These are painted and taped up."
The initial scion wood is around 8 millimetres in circumference, but after eight months the canes can double in size, providing strong wood for laying down the following winter (generally just three canes). At pruning the spurs have to be carefully managed to ensure a strong new head is established.
While the success rate is high, Stead says things can go wrong, and sometimes they encounter blocks where the grafting just doesn't work, for unknown reasons.
When it comes to what growers are changing from and to, Stead says it depends where in the country the vines are. In terms of Marlborough, which will see up to 50,000 vines top grafted this year, the majority is going towards Sauvignon Blanc. Given the lack of available land, it is not unreasonable that growers are changing from other varieties to the flagship. Although Stead says it is also site specific.
"Some wineries are not happy with what (the grower) has on that site. Like areas of Pinot in Rapaura, which is strong Sauvignon country, is being grafted to that. Whereas on the other side of the valley, they are top grafting from varieties like Riesling and Pinot Gris to Pinot Noir."
In Nelson where close to 20,000 vines are being top grafted, it is from Riesling to Chardonnay mostly.
In Hawke's Bay – 20,000 vines – it is from a range of varieties to Sauvignon Blanc.
And in Cromwell – 15,000 vines – it is from Riesling and Pinot Gris to Pinot Noir and Chardonnay.
With 12 people working for him, Stead says there is a small window of opportunity to complete the task.
"We get through about 2,000 plants a day, which is a fair bit. But it is back breaking work, because you are bent over all day."
In terms of costs, he says there is a difference between waiting up to three years to get an income from fruit with new vines, and making money within 18 months with top grafted.
Even though there is a full root structure providing the nourishment to the vine, Stead says you have to ensure they get plenty of water during the initial changeover.
"You have to treat it like a young plant, they like lots of water over the summer. And you have to train them, because they are still quite weak (at the grafting site). Basically if you treat it like a young plant, it will do okay."
