From the Vineyard: The Impact of Scorching Heat on the 2018 Harvest

10th Aug 2018 @ 13:20 by Matt


September 2018

By Penny S. Adams, winemaker and viticulturist for Wedding Oak Winery

It’s hot enough to fry an egg on the bed of a pickup truck. We’ve had another summer of record heat in Texas. What does this heat mean for our 2018 harvest at Wedding Oak Winery?

This year has certainly not been an ordinary vintage in the Texas Hill Country. We started our year with record low single digit temperatures for extended periods that had us worried about winter hardiness, and now the excessively high temperatures combined with drought conditions are creating challenges in the vineyard and cellar. Excessive heat is not in itself a bad thing in regions like Texas, Paso Robles and other regions where it is the normal. However, heat can cause a stop in photosynthesis, sunburn on the grapes, and when combined with drought conditions fruit shrivel is inevitable. That’s what we are facing.

Vineyard sites, like our Estate High Valley Vineyard, that are perched high atop the limestone hills are protected from late spring frost damage. Yet, these same sites have shallow soils which make them more susceptible to drought issues, especially when combined with scorching heat. The 30+ days of 100+ degree temperatures and drought conditions have certainly shriveled the grapes which reduces yields.

Heat and low humidity contribute to excessively high evapotranspiration rates. We combat that with aggressive irrigation practices. We also implement a thoughtful strategy to keep the leaf canopy functioning and the crop hydrated until the fruit achieves true physiological ripeness. That’s not always an easy thing to do. Most grape varieties in the vineyards we contract have experienced heat stress resulting in smaller berry sizes and berry shrivel.

Photosynthesis slows or can even cease in the high temperatures we are experiencing this year. The degree of the impact for each grape varietal is dependent on the phenological stage of development the grapes were in when the intense heat disrupted photosynthesis. Roussanne and Mourvèdre, both late varieties for us, struggled due to the skins not being ripe before the heat set in. Good early season canopy management practices limited sunburn damage in our managed vineyards. However, growers with younger blocks, less leaf canopy and more exposed fruit have been impacted. Tempranillo, Syrah and Albariño with more shaded canopies performed better than more open canopy varieties like Viognier and Mourvèdre.

There is also good news. We have excellent grape quality in 2018.

While grape growers are frustrated with the reduced yields this year from the need to hold fruit until fruit is truly ripe, our winemaking team is happy with the more concentrated flavors and aromas which will define the 2018 vintage in the years to come. In our Estate Vineyard the Syrah Block shrivel is an inherent annual characteristic that develops a concentrated sugar and desirable deep brooding fruit quality to the fruit and finished wines.

We have completed the harvest of our Hill Country white grape varieties. Our Albariño from our Wildseed Farms Vineyard, harvested very early this year on July 23, was very high quality and is looking beautiful in the cellar. We finished the white grape harvest by hand picking the Roussanne at our Estate High Valley Vineyard earlier this week. Despite the heat we were able to hold the crop with the protected canopy until ripe. It is a beautiful crop with intense aromatics.

The red grape varieties from our Estate Syrah and Grenache came into the cellar with exceptional quality; high brix and good varietal character. Our first crop of Tempranillo at Wildseed Farms Vineyard was harvested this week with high yields and good chemistry. It is looking nice in the cellar. Another standout for us this year is Negro Amaro from Hye Top Vineyard, that reached its true ripeness, holding its acid until harvest, producing a rich, rustic and highly tannic wine. We’re awaiting harvest of Aglianico and Carignane in the next several weeks.

The 2018 vintage in the Texas Hill Country is light in yield, meaning less wine in the 2018 vintage. The good news is the wines will have highly concentrated flavors. Most importantly, grape varietal response to the heat and drought will help our region better define varieties best suited to our unique growing conditions in the Texas Hill Country. It has been a great growing season.