It's the time of year when we start to worry about weed control. The winter's rains are all but over, and the organic vineyards are dry enough to get a tractor into. If we get the weeds now, before they go to seed, it makes our lives easier for the rest of the year. And, after a dry winter like this one, it's particularly important to get the weeds out early, before they start competing with the vines for scarce groundwater.
There are two parts to the weed control we do. The first is to take care of the cover crops that we've planted between the rows. How we do this depends on how much nutrition we want to put back into the soil. If we feel that the soil needs a significant boost, we'll till or disk the cover crop into the dirt. If we feel that the soils are rich enough (and grapevines generally do best in relatively poor soils) then we'll just mow the cover crops, and let the lack of rainfall kill off the surface plants. Of course, in a dry year, we're more likely to till the cover crop under, as it immediately stops the removal of moisture from the soil.
The second piece of weed control is the removal of weeds from within rows of grapevines. Speaking with other growers, this control of weeds between the individual vines in each row is the single largest hurdle to vineyards farming organically. And we used to really struggle with this, hand-hoeing the weeds away from the vines. It's terribly hard work, and slow (so, expensive) and, in the long run, not great for the grapevines, as it tends to remove soil from around the vines' roots.
In 2002, we were able to purchase the Tournesol tractor attachment, made by the French company Pellenc. This has been a revelation, and despite its high cost, we bought another in 2004.
It works in a remarkable fashion: it is pulled behind a caterpillar tractor, with a cultivating head sticking out to either side of the tractor. A rubber sensor arm protrudes a foot or so in front of the cultivating head, and monitors when it hits something solid (either a vine, or a post, or a wire). This allows the cultivator to rotate in and avoid damaging your vines or your infrastructure, while still allowing you to keep the area under the vines clear of weeds.
There are two more photos of the Tournesol at work below: