Stopping the rot

When Te Mata Estate viticulturalist Larry Morgan was working for Hort Research, he spent a lot of his time poking around the vineyards of Hawke’s Bay. Thanks to the weather conditions being just right for the ugly fungus botrytis, there were some years, especially in the early 1990s, which were particularly devastating for grapes. Even this year, he says, quite a few Hawke’s Bay growers found themselves at the mercy of juice-sucking, skin-wrinkling, grape-rotting mould.

But vintage 2005 was a good one for Botry-Zen, a sworn enemy of botrytis. The listed Dunedin biotech firm, formed five years ago to commercialise a biological (as opposed to chemical) solution to botrytis, had at least three good reasons to break out the bubbly.
Before we get any further, a quick explanation: Botry-Zen is the name of the company, but also the name of its product. Botry-Zen, the product, is a fungus that attacks botrytis. Botrytis (also called grey mould or bunch rot) likes cool, drizzly weather and, once on the grapes, sucks out the moisture, leaving grapes to wither and die. It wreaks a conservatively estimated $35 million worth of damage on New Zealand grape crops every year. (In some situations, botrytis — then called noble rot — is a welcome guest in the vineyard because it produces sweet, late harvest wines. But all wine is not meant to be for dessert.)

Now back to the reasons for the bubbly. First, in the war for domination of the nation’s grapevines this harvest, Botry-Zen’s fungal product triumphed over, or at least equalled, chemical spray performance against the botrytis fungus in 79% of grape blocks it was used on, says the company. In the rest of the blocks, the company claims, there were unique or localised dark forces that explained its marginally less impressive results.

On top of that, while Botry-Zen is effective for the first two-thirds to three-quarters of the growing season, lab and field work with Botry-Zen II, a product that will prevent botrytis attacking grapes late in the season, also showed strong promise. But that’s all the company is saying on this subject while further development work is underway.
Thirdly, this year the company achieved New Zealand registration of Botry-Zen in a new, dry granulated form. Given the original product came in ten-litre pails and looked and handled like slimy, sloppy Vegemite, the invention of the nice and tidy, extremely water-soluble, transport-friendly, granule Botry-Zen is a biggie. Think “export” here.

The new, dry product was bought by New Zealand winegrowers and used on more than 200 hectares of grape land in the current financial year as well as on several kiwifruit, peony rose and blackcurrant trial blocks. Very limited New Zealand sales were also made in the previous year, the company says.

Botry-Zen, which works by competing with and beating botrytis for its food source, was also trialled in California, Italy, France and Germany with similar positive results to those back home.