Navigating a Rainy Vintage

From John, October 27th, 2019

The last 5 vintages in Oregon have been pretty easy affairs as far as weather during the harvest goes. However, 2019 was another matter entirely. After successfully fighting the perfect conditions for powdery mildew* all summer we entered September with our fruit in pretty good shape.

A bit of rain in early September is not unusual and usually not a problem. Unless the berries are within approximately 2 weeks of being ripe, moisture on them is not a big problem. But once one gets inside that 2 week window, the issue of rain can be a serious issue. At that point the skins soften up and the berries are more prone to absorbing moisture, therefore becoming more susceptible to fungal infections. If a single berry splits at this point it is food for the lurking fungal spores and the game is on.

In 2019 significant rain fell early in the third week of September. Fruit in the lower elevation vineyards was not quite ripe, but it was close. And this where the winemaker’s decision comes into play: picking early will avoid botrytis** infections but the fruit will be under ripe. Waiting through the rain will allow the fruit to ripen more fully but now risks inclusion of fungal infection. Because the rains were emanating in the North Pacific gyre, and would therefore be cold, we chose to wait. The results were of course mixed: by the time we picked the following week, the fruit was ripe though the sugar was reduced by the absorption of rainwater and some botrytis had started to grow.

By contrast fruit in the higher elevation vineyards was not quite ripe enough to be heavily affected by that rain event. As a result, when we picked those vineyard blocks another week later only negligable botrytis had developed and the sugars were perfect.

As the season wore on, however, with more rain events interspersed with sun, botrytis became a bigger factor. Fortunately at that point we are mostly harvesting white grapes and they are not so negatively affected by botrytis as are the red grapes. Botrytis kills color (so bad for making red wines) but can add interesting aromas/flavors, such as honey and apricot notes (so good for increasing complexity of white wines).

Any time that one gets a generally rainy harvest scenario, the wines are likely to be mixed in terms of interest and quality. And it puts the easy vintages into perspective!

 

*Powdery mildew (Erysiphe necator) is a fungal infection that appears as a whitish-grey powder on leaves and berries. Disease development is strongly favored by high humidity and cloudy weather, in addition to relatively warm temperatures. Practices such as proper pruning and leaf pulling  promote an open canopy with good air circulation and light penetration, which can reduce conditions that favor powdery mildew development.

**Botrytis cinerea, a grey-brown fungal infection, is the most common form of wine grape rot in Oregon.  Though beneficial in the production of dessert wines, botyritis infection in Pinot noir is not desirable!

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