Instead of walking vine rows and checking grape clusters in early October, as she has for the past three decades, viticulture consultant Prudy Foxx is pondering whether to go sailing in nearby Monterey Bay or take to the Santa Cruz Mountains trails with her bike. 

Her company, Foxx Viticulture, Santa Cruz, Calif., works with growers throughout the 1,500-acre Santa Cruz Mountains appellation situated between Monterey Bay and the Santa Clara Valley. On Oct. 1, they picked the last grapes of the 2015 harvest.

“It’s absolutely unheard of to be finished that early here,” she says. “Even the wine makers are in shock.”

However, despite the various readings of high grape quality, harvest celebrations were dampened by disappointing tonnage figures – especially in some of the most affected blocks of Pinot Noir, where yields plunged to as much as 80 percent below average. Some blocks weren’t even picked.

“Although those are extreme numbers, hardly any grower escaped this year without some reduction in yields,” Foxx says

She puts the blame primarily on the unrelenting, rainy, damp weather during bloom. This handicapped the pollination process, leading to a poor fruit set and shatter.

“We had vineyards with sound, open canopies and good air flow that remained wet 24 hours a day for three weeks during bloom,” Foxx recalls. “Flowers rotted off, and pollen couldn’t move down the tubes to make fruit. There’s no kind of spray on the planet that will fix that.  If your vines bloomed during that gloomy wet period, you were done. If they bloomed earlier or later, the set was pretty good.”

In addition, an untimely April frost that blackened buds contributed to the losses this year by destroying the primary fruit set.  “We are seeing a bountiful second crop this year produced by buds that emerged after the initial loss,” Foxx says.  “However these clusters are late ripening and economically challenging to pick. We can really feel like Burgundy this year, is the local joke, referring to the more common incidence of wet, dismal spring weather in the Pinot Noir growing regions of France.”

Pinot Noir yields suffered the most and generally were down about 60 percent from normal, she notes. Chardonnay tended to produce more of an average yield. However, smaller clones, particular Dijon Chardonnay, were off an estimated 50 percent. Depending on timing of the bloom, Syrah yields varied between average and just 20 percent of that.

“Even in vineyards with good conditions for pollination, like Cabernet Sauvignon and some Syrah clones, fruit size was affected,” Foxx says.

In some cases, growers with vines that appeared to set a good crop were dismayed when the harvested grapes failed to fill the bins as expected because of smaller, lighter clusters, she adds.

As Foxx sees it, drought may have contributed to that but only indirectly. While water stress could account for some of the light-weight fruit, it doesn’t explain the similarly light berries growers harvested from irrigated vineyards, she notes.

“I think the lighter weights and lower yields are more a result of a shorter growing cycle and letting soils get too dry,” she says. “Because the grapes ripened so early, growers didn’t have time to re-wet or to maintain soil moisture enough to prevent dehydration of fruit still on the vine during some 100-degree-plus temperatures we had in September. In addition, the shorter growing cycle did not allow for normal sizing of fruit prior to veraison.”

Despite the drop in production, the new crop brought smiles to the faces of the growers.

“People are excited,” Foxx says. “The chemistry looks good and pH numbers are perfect. However, sugar readings may be a little high. Because the grapes ripened so quickly, crews weren’t always able to get out to every vineyard on the same day the grapes were ready. But, the small, perfectly formed clusters have made for some incredibly intense flavors with excellent skin to juice ratios, especially in normally larger clusters like Cabernet Sauvignon.”

This year’s poor pollination and resulting limited and shattered formation of the fruit reinforced her thoughts about the role of canopy management in encouraging fruit to set during challenging weather conditions. This spring she experimented with some gentle early shoot-tipping techniques used by growers in the Burgundy region of France.

“Basically, it’s designed to re-direct plant hormones in the tips of the vine into the lateral shoots to invigorate the potential buds trying to set fruit,” Foxx says. “Where we experimented with this technique we saw improved set.”