Building Resiliency and Quality in California Wine Grapes
Our partner in California, Regenerative Crop Consulting, Inc., has been working with a 65 acre wine vineyard in Paso Robles, CA since summer of 2020. The predominant variety is Cabernet Sauvignon. At the beginning of the project, the vines were stunted in growth, underperforming in yield, and suffering from lime-induced iron chlorosis. Our grower was fully conventional, but interested in becoming more regenerative. He purchased this vineyard over a decade ago from another grower who had planted it. This original grower had over-applied Roundup to the young vines, which had stunted vines and root growth. Not an easy starting point, but as we like to say, we are here to help fix broken dirt.
In the fall of 2020, we began by applying two gallons of Provide and two pounds of Revive per acre in a post-harvest application. In 2021, we used Provide and Revive in small applications totalling four gallons Provide and four pounds Revive throughout the growing season on top of his conventional program. It looked like there was going to be a large crop set, but there was heat and stress during shatter. This resulted in much lower yield than expected. The vines still showed signs of stunted growth and iron chlorosis that was not corrected with the conventional fertilizers and the Provide/Revive applications.
In the winter of 21/22, the grower planted a cover crop and then grazed it with sheep prior to bud break. The grower committed in the 2022 growing season to drop all herbicides and salt-based conventional fertilizers and use organic materials derived from protein, amino acids and seaweed with Provide and Revive. Rather than spoon-feeding Provide and Revive, like in 2021, we applied two gallons and pounds per acre prior to bloom and then again after bloom, trying to reduce stress during shatter. Vine growth looked terrific and crop set initially looked good, but extremely high temperatures during shatter occurred again, worse than in 2021, and the crop set dove from a predicted 5 tons per acre to 2.6 tons per acre. Then the vines went through an extremely hot August with temperatures above 108 and hitting 116 for a week. The vineyard showed extreme resilience through the stress and the grapes held up on the vine. The wine buyer, J. Lohr Vineyards, reported the cabernet fruit was the highest quality wine grape they had seen on this vineyard and was comparable to their best wine block anywhere.
The grower is going to continue to use Provide and Revive in 2023. In late fall of 2022, he broadcast compost and gypsum on the vineyard with the hopes of speeding up the improvement in soil health, along with planting a cover crop again. We have been taking sap tests since fall of 2020 to determine vine nutritional needs and to see if anything shows up that might be affecting the poor crop set during shatter. We believe that correcting very poor soil conditions takes time, and there are no quick fixes in a natural, regenerative and biological approach. That said, with the current environmental factors facing California, this approach is key to building resilience and making great wine.
