Chronicles of a Dirt Farmer: On Crop Load

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At RSV, we’ve made a conscious decision to farm for ourselves the vines whose grapes we use to make wine. We think the benefits outweigh the risks: knowing exactly how our vineyards are farmed gives us a measure of control most wineries don’t have. Producing wine, a value added product, means we as growers don’t have to sacrifice quality for production in order to make ends meet.

For an estate winery like ours that does not purchase any fruit, the amount of grapes we get every year is our lifeblood. In the low years, like 2011, we just make less wine – and consequently, less money, even while the cost of farming remains relatively the same. In the big years, like 2012 and 2013, we can barely fit all of the grapes we harvest into our cellar.

Vineyard horizon

credit Rob Sinskey

This means that I anxiously await our lag phase crop estimate each year. This is the most accurate estimate of the season and it comes barely two months before harvest.

“Lag phase” is a physiological milestone about 45 days from mid-bloom, when the seed in the berry starts hardening and the fruit stops growing to allow the seed to mature. This process takes about two weeks – during which time the grapes “lag” behind in growth. Hence the name. At the end of this process comes veraison as the berries start to gain in size once more.

If one weighs the grape clusters at the exact moment that lag phase starts, the coefficient is 2. By which I mean that the berry will double in weight by the time it is harvested – this is why the lag phase crop estimate is the most accurate of the year. It gives us a measurable idea of cluster weight, which can vary greatly every season. Cluster weight, multiplied by the amount of clusters per vine, over a given acreage, will let us know what the tonnage at harvest most likely will be.

Producing wine from the vines we grow also makes us better stewards of our own land – it’s not just what will this current vintage give us, but how can we care for this land so it keeps producing for the future? Which means we farm for balance, for sustainability – for the whole vineyard ecosystem. It’s what drew us to organics and biodynamic farming methods in the first place. It’s why I do what I do as RSV’s farmer.

Vineyard vista

credit Rob Sinskey

One can only make the best wine from the highest quality fruit; mediocre fruit will never rise above its own banality. As such, a grapevine needs enough leaves to ripen the fruit it’s carrying – to make enough sugar and process enough nutrients. It also needs a healthy root system, which comes from healthy soil. If the vine doesn’t seem to make it, if we think the vine is overcropped to the point it would affect quality or health, we need to drop fruit. This is best done between bloom and veraison – as this will affect the quality and growth more than after the grapes have gained color.

Irrigation at specific physiological points can also have a profound effect on tonnage – especially in a shallow-soiled region like Carneros. I can have almost total control over vigor depending on when – and how much – I water. In years like this, with some almost-empty reservoirs, I know I won’t be able to get a full crop. But I do know that I’ll be able to at least time irrigations to get the most crop I can and keep the vines healthy. I water at bloom, lag phase to veraison, and then save one more irrigation for sometime before harvest to keep the canopy from crashing. I know that the fruit might get sugar ripe before physiologically ripe, but that is the risk I must take if I don’t have enough water.

In an ideal situation, I do not stress the vines at all before veraison. I give them what they need to grow – just not so much that they turn into wild, green beasts. I make judgements based on the color of the leaves, the pressure bomb, and a shovel. I have not found a use for fancier methods – or any that are as reliable as my eyes, my instinct, and a look at the soil.

As always, it’s a balancing act. This year, the vines seem balanced – the lag phase estimate came in on the high side of average. So we are not anticipating the crazy tonnages of 2012 and 2013, but it should be a lot better than 2011. Assuming, of course, that I don’t run out of water before then. In this case, an early harvest will be a blessing, as this will help me get through the season before we run out of irrigations.

As with all things in farming, time will tell.

 

Debby Zygielbaum is the Vineyard Manager (or, as she’s fond of saying, ‘Dirt Farmer’), at Robert Sinskey Vineyards in Napa and a frequent contributor on Nopalize. She can be found @walkthevine on Twitter and Instagram.