Drought Tips For Grape Growers
by Mark Scaramella, February 19, 2014
Local grape growers would have trouble finding a better spokesperson than Sean White, General Manager of the Russian River Flood Control District, an entity that controls the 8,000 acre-feet of Lake Mendocino water owned by Mendocino County. The rest of the water in Lake Mendocino is the property of the Sonoma County Water Agency where White worked before moving north to Mendocino County.
Along with White and former Supervisor Richard Shoemaker (who’s now on Sean White’s Russian River Flood Control District Board), I was a guest on a recent session of “All About the Money,” a bi-weekly KZYX talk program hosted by John Sakowicz. The topic was water/the drought.
When the subject of vineyard water consumption inevitably arose, I made a few modest observations comparing grape growing methods in France to those in California.
For example: the government of France has strict laws that limit grape yields, to less than one ton per acre in many areas. This not only improves grape quality, but ensures that no irrigation is needed for the deep-rooted French vines.
By comparison, grape yields per acre in Mendocino County are over four tons per acre.
When I pointed this out, Mr. White said that grapes use less water than some of the other Mendo crops that preceded grapes, such as hops, pears and apples.
In the past Mr. White has said that grape growers don’t need regulation because they are “self-regulating” and practice “voluntary conservation.”
We couldn’t get into much of a debate on the subject because the topic of the show was the drought, not grapes.
But there are a few points I would have raised if there had been time:
• If grapes are so water thrifty, why has the Russian River become “fully appropriated” since grapes became the primary crop in inland Mendocino County?
• And why didn't the thirstier crops of yesteryear like apples and pears (which also happen to be food, not a pricy intoxicant), need hundreds of ponds for irrigation and frost protection?
• And why did the State Water Resources Control Board propose that the Ukiah area grape growers develop and submit plans to prevent future fish strandings by excessive simultaneous pumping for frost protection?
• And if the grape growers are so committed to voluntary conservation, why did the Water Board even need to propose that such plans be developed?
Aside: The requirement that grape growers prepare their own “fish-stranding avoidance plans” (such as have existed for years in Napa County) was met with such an outcry from Mendocino County growers that an angry crowd of Grape Growers Against Regulation crowded Judge Ann Moorman’s courtroom to argue that State bureaucrats hadn’t made enough of a case that such plans were necessary. Never mind that the state wasn’t able to prepare a case because 1. Professional biologists have not been allowed on the grape growers’ property to document all the fish kills, and 2. Even if they were, there aren't enough of them to uncover all the strandings on the overtapped tributaries of the Russian River, many of which occur in a brief period of time.
New strains of thirsty, shallow rooted grape varieties are being grown on thousands of acres in Mendocino County where they could not be grown unless there was an abundance of cheap water for irrigation, frost protection and growth control.
If the local grape growers weren’t represented by the professional biologists like former Sonoma County Water Agency staffer Sean White, they’d have to settle for less polished bureaucrats like the local UC Extension office’s grape guy and vineyard owner, Glenn McGourty.
Back in 2009 McGourty, Shoemaker and County Supervisor John McCowen traveled to Sacramento where they informed the State Water Resources Control Board that any regulation of the wine bloc's water intensive irrigation and frost protection methods could retard high end booze production.
McGourty, McCowen and Shoemaker, accompanied by a hyper-indignant grape grower named Dennis Murphy, opposed water regulation — any water regulation. The three of them insisted that the wine industry has built more ponds to store water for frost protection and that an “educational” program has been devised to inform grape growers that the wise use of water is, well, wise.
Murphy was so overwrought as he spoke to the Water Board that he was trembling and nearly in tears: “I’m extremely upset that a federal agency could come up here and make direct accusations about growers and the consequences of irrigation. And then clam up claiming it’s under investigation. That’s wrong! That’s not right! These are rumors. We need to know more.”
Boo-hoo and wah-wah.
But it fell to McGourty, Mendo’s tax-funded grape guy, to make the single most ridiculous statement at the hearing.
“Regulations never work. Look at marijuana. It’s illegal as heck and yet we have marijuana all over northern California and our county in particular. So people don’t necessarily go along with regulation.”
By that logic Richard Nixon would never have founded the EPA because “people don’t necessarily go along with regulation.”
The difference between the two industries, however, is considerable. The wine industry is legal, ultra-legal you might say, extra-legal perhaps, complete with its own elected representatives all the way up to Congressman Thompson (no longer Mendo’s congressman, but…), a grape grower himself who chairs Congress’s wine subcommittee. It also has fixed addresses and the names of its owners are public record.
The dope industry is not legal. It can't be regulated until it is legal. Both the wine industry and the pot biz help themselves to public streams, but according to McGourty, neither need regulation, nor would abide by it even if there was any.
* * *
With this background in mind we were very interested in a recent report by County CEO Carmel Angelo: “On January 29th, the County’s University of California Cooperative Extension, UCCE, held a drought preparedness seminar at the Hopland Research and Extension Center for livestock and rangeland owners in both Lake and Mendocino counties.” Which just happens to be McGourty's place of employment.
(Notice the avoidance of the word “grapes” in Ms. Angelo’s announcement, as if grape growers are somehow part of “livestock and rangeland owners.”)
Angelo's press release continues: “The UCCE’s Glenn McGourty has reached out to his colleagues in Australia and specialists from the Australian Wine Research Institute to see how grape growers there have been dealing with their own severe drought. Glenn will use this information to give a short presentation to the Lake County Winegrape Commission and the Lake County Farm Bureau on February 26th. Glenn is also sharing this presentation with local agricultural associations including Mendocino Winegrowers, Inc."
So what did Mr. McGourty learn — and pass along more or less unthinkingly — from his Australian counterparts about grape growing in a drought?
“Although wine grapes are considered more drought-tolerant than most horticulture crops [our emphasis], insufficient water can lead to a reduction in vine growth, fruit yield and quality.”
In other words, less water = less yield (or more water = more yield] as previously noted.
“In order to manage wine grapes under limited water supply it is important to understand the annual growth cycle of a grapevine. There are five main growth stages: budburst to flowering, flowering to fruit set, fruit set to veraison [the onset of ripening], veraison to harvest, and harvest to leaf fall. The amount of water required at different growth stages will depend on variety, rootstock:scion combination, climate (rainfall and evaporation), soil type and depth, and crop load [i.e., density of grapes and planting]. The growth stages also vary in their sensitivity to moisture stress.”
Note here the importance of grape and rootstock variety. Mendo grapes, especially those planted this the 21st century, are not the drought-tolerant type, as apparently they are in Australia where drought has long been a major factor in agricultural enterprise.
“The following outlines some general concepts to consider when budgeting or prioritizing irrigation.
• “No irrigation. Abandoning the block or patch of vines, after one season without irrigation it may [our emphasis] be possible to revive the vines the following season. Survival will depend on variety and rootstock. Pests and diseases still need to be managed as these may carry over to the next season.”
It’s not likely that Mendo grape growers will voluntarily “abandon” any of their grapes — unless they literally have no water for them.
• “Irrigation for survival. To maximize the potential for a crop next season, it is important to maintain bud fruitfulness and the vine’s carbohydrate reserves. This could be achieved by winter pruning to reduce bud numbers for this season and maintain a smaller canopy.”
Winter pruning is already common in local vineyards, but not as a water shortage tool. If it was, they’d use pruning to deal with frost damage, not huge applications of overhead sprinkler water.
“Shoot thinning and reducing crop load by removing bunches shortly after berry set will reduce transpiration demand and the amount of water needed to ripen the crop. Limit shoots growth to maintain eight healthy leaves per shoot by withholding irrigation or summer hedging. Avoid large amounts of leaf loss during veraison to harvest. Carefully observe vines for signs of early water stress in conjunction with soil moisture monitoring to maintain functioning vines.”
These are useful ideas for any grape crop, not just in a drought. Trouble is, they require extra labor, something that even the $40 a bottle and up growers are loathe to employ.
• “Irrigation to minimize loss of yield. Avoid severe water stress during flowering and fruit set as this will reduce fruiting potential in the current and subsequent season. Water stress after fruit set has less impact on fruiting potential but may reduce berry size and yield. The least sensitive period to deficit irrigation is after fruit set to veraison. Applying deficit irrigation below the vine’s water requirement during this period has been shown as a successful strategy to conserve water. However, avoid excessive water stress.”
In other words, don’t overwater.
• Varieties and wine styles. The water requirements for different varieties and wine styles can vary considerably. Red grape varieties usually require less water than whites. Grapes for aromatic and lighter wine styles require more water to minimize stress than do grapes produced for more full bodied wine styles. Excessive exposure in smaller canopies due to water stress increases the risk of sunburn and deleterious effect on flavors and quality, particularly on many white varieties.”
But the large majority of grapes in inland Mendocino County are white, mostly chardonnay.
“Methods to reduce moisture stress and conserve water supply:”
• “Apply mulch. Applying mulch along vine rows will reduce evaporation losses from the soil. Studies have shown that mulch can significantly increase soil moisture content at harvest. Mulch also reduces the competition for moisture from weeds.”
• Suppress growth of cover crops. Mow or spray off cover crops early in the season so they do not compete for moisture with vines.”
“Spray off”? What could that possibly mean? Even more herbicide, apparently, than is now used.
• “Control weeds. Weeds compete with the vines for moisture. Good weed control will mean more water for the vines.”
• Ditto: More herbicides, more poison. (Bet you’re surprised to learn that additional pesticides are one way of dealing with a drought.)
• Water at night. Watering at night can reduce evaporation losses by up to 10%. It also allows you to take advantage of off-peak power.
Most local grape growers already do this.
• “Maintain irrigation systems. Fix leaks in irrigation systems. Ensure irrigation system is working efficiently.”
• “Consider planting new vines on rootstocks. Rootstocks such as Ramsey, K51-32, Paulsen 1103 and Richter 99 and 110 are more drought tolerant than Schwarzmann and 34EM which are similar to own-rooted vines. Drought tolerant vines have a greater ability than own-rooted vines to explore deeper into the soil to extract water. This is a longer term option. Some rootstocks may cause vigor problems in years with average or above rainfall.”
This suggestion flies in the face of standard UC Ag Extension advice to use less “vigorous” shallow rootstocks to maintain more control over ripening and harvest times.
• “Pruning level, shoot and fruit thinning. Insufficient irrigation may result in fruit on heavily cropped vines not being able to ripen fully and having poor color and flavor. Set the vines up to best handle the likely shortage of water. This can be done using a combination of heavier winter pruning to reduce bud numbers, shoot thinning and summer hedging to reduce canopy size, and bunch thinning to reduce crop load.”
This is a good idea, but will substantially reduce tonnage per acre and thus significantly reduce revenue.
• “Reduce evaporation and leakage losses from dams. Evaporation can be reduced from several dams (aka, “ponds”) by pumping into one dam. This reduces the total surface area exposed to the elements and increases water depth.
“Applying protective films (e.g., Aquatain®) to the surface of water in storage dams or establishing wind breaks can reduce evaporation losses by up to 30%).”
According to the Aquatain website: “WaterGuard is produced from polymers which repel each other very strongly when they come in contact with the water. The components of WaterGuard are safe chemicals, and many of them are used in food and pharmaceutical applications.” (Wikipedia: Synthetic Polymers are made from familiar synthetic plastics such as polystyrene (or styrofoam).)
• “Irrigation scheduling strategies. Regulated Deficit Irrigation (RDI), Partial Rootzone Drying (PDI) and Sustained Deficit Irrigation (SDI) have been developed to improve water use efficiency and reduce the amount of water needed for wine grape production. These techniques could be considered in a season when water is limiting. Good soil water content monitoring is essential to determine how much water to apply and when in order to avoid excessive water stress.”
The Aussies’ “strategies” may work in reducing water usage, but they will produce significantly fewer tons of grapes per acre, will probably cost more to implement, will involve application of additional pesticide and herbicide, and most won’t be practical to employ for this year’s harvest if at all.
Thanks Mr. McGourty. You can go back to sleep now.
* * *
Given the historical resistance to change exhibited by Mendocino grape growers almost all of whom began growing wine grapes in the last 40 years, even the modest Aussie conservation suggestions will be ignored — with the exception of increased use of pesticides which many local grape growers will go along with.
Instead, if the drought continues as expected, the grape growers will be forced to take their losses. Then they’ll go to Sacramento and Washington DC hat-in-hand for a drought-emergency bail-out from Congressman Thompson and his fellow wine lovers.
Congressman Mike Thompson visits his Lake County vineyard. Photo by Jim Wilson/The New York Times