How these 3 biodynamic farmers control the weeds

Toby Bekkers, viticultural consultant with a biodynamic bent, sees a lot of organic and biodynamic winemakers. This is his take on them: “They go from a system where you buy products to deal with problems to a system that is skill-based and much more proactive, which means they’re in the vineyard more often. People who go down that path are better growers or better observers or they become so quickly.”

So how do these sensitive souls control unwanted weeds and fungus in the vineyard? We asked three winemakers from three very different climatic regions what the tricks of their trade are. And, although the scale is much larger, there are lessons here for the home gardener.

Chris Carpenter is a biochemist, a viticulturalist and one of the three Carpenters — his mother Sue and father Dave the other two — who make Lark Hill wines using biodynamic methods 860 metres up on the escarpment at Bungendore north-east of Canberra.

At Lark Hill, Chris told us, weed control is physical, the first line of defence being mulch. On established vines, “We use a deep mulch made with used sawdust and stable litter from a nearby equestrian centre that we compost for a year. It’s not quite broken down but it’s pretty neutral in terms of nitrogen demand.

“Every second year, each block gets this mulch spread in a 45cm-wide band 15cm deep under the vines. The fact that it disappears tells us we’re sticking all that carbon back in the soil. Any weeds that come through the mulch we pull out easily — there’s no deep rooting. We also use a brush cutter to mow under the vines. Every time we mow, we throw all the grass clippings back in the mulch.

Mildew and fungus were big problems in the 2010 season in south-eastern Australia. “We had our annual rainfall in three months,” Chris said. “It rained three in every five days.” The major diseases in humid conditions are downy mildew, powdery mildew and botrytis.

Lark Hill used to spray milk to prevent powdery mildew, but stopped so the wine would fit into the vegan regime and began using Eco Carb, an organically approved potassium carbonate spray that creates a “hostile environment for powdery mildew but is friendly to insects”. And at Lark Hill that especially means lady beetles, which eat the scale.

Another effective anti-fungus tool is chamomile. “A spray made from a kilo of chamomile flowers boiled up in 10 litres of water, then steeped overnight and added to another 200 litres of water. It’s a good control if you have active fungi in the vineyard.”

“There are two ways of managing weeds,” organic winemaker David Lowe of Lowe Wines in Mudgee told us. “You kill them or you out-compete them. We practise both.” The killing is done using a Weed Zap, another organically approved spray, made from plant extracts, which, David tells us, “stinks incredibly and burns off the foliage. We use it for one to two years — it’s the best we can do for the young vines. You get them growing so they’re out-competing the weeds. Once they’re strong enough the roots go deep, looking for moisture, and the weeds are no longer significant.

“The second method is to outgrow the weed with benign native grass — and that’s what we do with our mature vines. They grow well over the end of winter into spring then they hay off in summer and form a mulch, which stops the annual weed grasses. And you slash the heads off the annuals so they don’t regenerate. If you’ve got bare ground when it rains, the horrible weeds spring up. You’ve got to have the ground covered with native grasses.”

Out on its own, 70km inland from Denmark in the Great Southern Region, is Frankland Estate. Hunter Smith is in charge of many aspects of the winery’s operations; he spoke to us on weed management, which is combined with the estate’s other interest: wool growing.

“We’ve just started to graze (under the vines) again after six years. We had a large broadacre farm before we began viticulture and we still have a few little sheep running around. They help reduce the grass and allow a strong flush of clovers in spring, which are good for fixing nitrogen in the soil.

“When we started, we didn’t graze at all — we wanted to build up the organic matter. We were growing a lot of green matter, which was mulched back on top of the soil — just mown and left to build up. This winter (2011), we’ve got the sheep back in because we’re comfortable with the amount of organic matter we’ve put back in the soil. It’s just a matter of controlling the taller native grasses and letting the clover come forward.”

If you make a conscious choice to drink organic or biodynamic wine, these stories will make you feel better about your choice. But is there also a health risk with conventional — or chemical — farming of grapes? That’s a more complicated question and one we promise we’ll turn to in the future.

Tasting notes

• Lowe 2008 Tinja Shiraz: Spicy paprika on the nose and in the mouth, followed by plummy fruit in the middle palate. A terrific summer red with lamb.
• Lark Hill 2011 Grüner Veltliner: A beautiful wine, refreshing acid with spicy fruit, elegant and punchy at the same time. Great seafood wine and tough enough to withstand a little chilli.
• Frankland Estate 2009 Rocky Gully Cabernets: Inky cabernet nose, with soft fruit and meaty richness on the palate, soft tannins at the end. European-style food wine, perfect with pork.