Grapevines are hardy but the drought concerns many growers

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By Craig W. Anderson

The current drought is causing real concerns up and down the Central Valley just as it has for nearly two years in the absence of significant rainfall and a slim snowpack.

“If this drought is the prospect for 2022, things could get really ugly,” said San Joaquin Farm Bureau Executive Director Bruce Blodgett. “We’re in the midst of a major drought and the state continues to ship water to the ocean and to display water contradictions in its thought processes and policy decisions.”

“The grape crop is average to light in Lodi for most varieties so far,” commented Kevin Phillips, vice president of operations for Michael David Winery. “However, the drought is having a serious effect in       certain localized areas and even historically good wells are starting to show some water quality and availability issues.”

The USDA National Agricultural Statics Service said California produced 3.6 million tons of winegrapes last year and this year the yield is anticipated to be less than that; at least the industry won’t have to cope with the widespread smoke pollution from wildfires. It will, however, have to deal with the seemingly unending chain of yet another drought among a decades-long series of them.

“This drought definitely contributed to lower yield this year,” said Aaron Lange, vice president vineyard operations for LangeTwins Family Winery and Vineyards. “The vines simply don’t have enough deep water in the soil profile, which affected cluster weight and contributed to overall vine stress.”

He also said when vines are under more stress “they’re more vulnerable to virus, fungi and other diseases such as sudden vine collapse and other multi-pathogen disease complexes.”

The LangeTwins Winery tasting room has been operating under an appointment only mode for some time in order to  comply with the various COVID mandates and recommended health and safety guidelines, Lange said, illustrating another aspect of the industry that has been significantly affected.

The current drought is the latest in a string of water-challenged years. The most recent was 2012-2016, which followed the 2007-2009 drought that came after the 1987-1992 dry spell that superseded the 1976-1977 water famine.

Blodgett pointed out that “a lot of grapes have been pulled out over the past few years but there’s no guarantee grapes will be planted again with some ground going to other crops.” The drought can be considered in future planning with more drought tolerant varieties but will they produce wines consumers will want to purchase.

Planning for the future of a winery is difficult enough without an ongoing drought potentially tossing a monkey wrench into the process.

A study in “Science Advances, September 2021” notes that a study of how different varieties of grapevines reacted to drought conditions revealed that “all of the varieties tested, including cabernet sauvignon and merlot, were found to be drought resistant instead of some varieties being more and some being less resistant.”

Drought affects water access and this could affect taste, the research revealed. In drought years, canopies may be short, stifling sugar accumulation and water stress may cause increased fruit character. “A drought can severely and significantly affect many aspects of how winegrapes translate to their finished product,” the researchers reported.

The relationship between winegrapes and water availability and its effects are complicated; drought years make the situation even more complicated. And there is the continual competition for ag, municipal and industrial water.

Part of that complication could occur because, said SJFB President David Strecker. “The drought brings up the question: what will the situation be down the road?” Does the future hold hope for water storage and conservation? “We need to get Sacramento and Washington, D.C., legislators and bureaucrats to take action in this regard. They just don’t understand how important storage is to continue supplying water in drought years and that’s very frustrating.”

Lange noted that winegrape replanting contracts “at a pricing level that adequately addresses the development costs and the associated risks of a new vineyard in our area, are few and far between.”

He pointed out some of the items that must be considered when replanting or planting new land to winegrapes: “Availability of water, the drought situation, the Sustainable Groundwater Management Act [SGMA], smoke exposure, virus, trunk canker disease and looming threats such as wildfires and the Spotted Lanternfly.”

Not knowing what the future holds is also frustrating, but SJFB First Vice President Andrew Watkins said, “We’ve made it through the drought this year but we may not get anything from New Melones next year; it’s been drawn down to well under a million acre feet, the water going to help fisheries.”

Dave Simpson, chair of the SJFB Water Advisory Committee who also farms winegrapes, said, “It’s been an interesting year with no surface water where I am.” He said about 80% of the county’s winegrapes are irrigated via drip systems. “Water use depends on location, grape variety and other influences. I’m skeptical about reducing the water we will get.”

Simpson said his grapes are irrigated about 15 times, using “close to two feet of water.”

The lack of rain and a hot summer has allowed spring mites to get established in vineyards, in Simpson’s case his cabernet had to be sprayed for mites “for the first time in about 20 years.”

Drought is usually accompanied by hot weather which encourages bugs and, said Simpson, “I heard it’s been 178 days since our last rain. This has been such a different year it’s required different planning.”

Growers need to plan for years ahead and anticipate market demand but the drought seems to be affecting planning more than anything else regarding looking ahead. Dry wells are becoming more common, more pipe and pumps are needed and if the drought continues new wells will be needed and current wells will have to go deeper.

In fact, wineries and grape growers began planning for the current drought in March via University of California workshops covering crop water and irrigation management, monitoring water status, irrigation scheduling, soil sensors and more with side excursions into Australian drought management techniques.

Simpson said a key element of future winegrape plantings will be determining what drought tolerant varieties will work and whether or not consumers will want the wines their grapes produce.

Lodi Winegrape Commission Executive Director Stuart Spencer, and winegrape grower, explains, “While the drought makes it difficult to plan ahead for years, drought resistant rootstock with varieties grafted onto it should allow wine grape farmers to select varieties that work the best.”

“As always,” he said, “markets have to want what is produced and that will be a major challenge for wineries should the drought continue.”

In 2020, the grape bearing acreage was 91,200, 4,700 less than the previous year; the yield per acre was 6.67 tons per acre compared to 7.11 in 2019; total tonnage in 2020 was 608,000 compared to the 682,000 of the previous year; and the price per ton was $560 in 2020, up over 2019’s $546.

It is possible long-term drought conditions were responsible at least in part for these slumps in production.

Among the tools being used in the battle against drought in wineries is a new one: Biochar, a soil amendment made from pulverized charcoal that helps build organic matter in poor or depleted soils and lowers a vineyard’s requirements for nutrient and water inputs; it can also lower production costs and the carbon footprint.

Biochar is porous, retains large amounts of water and provides a safe home for microbial populations and it can replenish and restore organic matter and minerals while improving water use and efficiency.

Biochar seems to be just what the soil doctor ordered for drought stressed vineyards.

It is only one of the tools used to help wineries and winegrape growers survive and thrive when the next drought rolls around.

“It’s been a very challenging two years, mostly on the labor front complying with ever-changing guidelines and supply management fluctuations,” Lange said.