When Clive Kaiser sprayed his patent-pending coating on a Cabernet Sauvignon vineyard, he wasn’t worried about spotted wing drosophila. Wine grapes are too tough for the flies, unless they’ve split or otherwise been damaged.

However, the coating, which acts like an extra cuticle, cut water demand in the vineyard by about 25 percent with no impact on fruit quality or yield, Kaiser said. Hence its name: HydroShield.

“Cuticles don’t stop water loss, it just slows it down. The thicker they are, the greater the water holding,” Kaiser said. “Once I created something that was thick enough, we hit the jackpot with water reduction.”

At Seven Hills Vineyard in Washington’s Walla Walla Valley, researchers applied four sprays of HydroShield, at two-week intervals as the vines grew, and tested at 50-percent and 75-percent irrigation regimes against the standard deficit irrigation program for the block.

Analysis of fruit quality by Washington State University enologist Jim Harbertson found the fruit from coated vines given 25 percent less water was comparable to the untreated control in terms of Brix, tannins and anthocyanins. Next, OSU winemaker James Osborne is making small batch wine to ensure the coating has no impact there either, Kaiser said.

With unpredictable water supplies in the growing regions of Eastern Oregon and Eastern Washington, and climate change predicted to increase drought frequency, the coating could be a powerful tool to stretch irrigation resources.

—by Kate Prengaman

Related: Nonpesticidal controls for SWD