03.21.2016  
 

Post-Mortem on a Disastrous 2015 Grape Harvest

At WiVi 2016 a viticulture consultant describes what went wrong on Central Coast

 
by Jim Gordon
 
scott williams andy mitchell central coast insights
 
The table shows hourly temperatures in Atascadero, Calif., during May 2015. Green highlights indicate 80 degrees F or higher. Source: CIMIS/Precision Ag Consulting.

Paso Robles, Calif.—Grape growers attending the WiVi 2016 Central Coast conference and trade show last week were hoping for some good news after the worst harvest in memory in 2015. Yields in many Central Coast vineyards dropped 50% below average due to a combination of extreme weather and accumulated drought conditions.

“About the only good thing I can say about 2015 is that it’s over,” said Lowell Zelinski, WiVi co-founder with Wine Business Monthly and owner of Precision Ag Consulting. As he reviewed the troubled vintage in two separate talks during the two-day event he expressed concern that last year’s bad weather might even have a negative effect on this year’s crop, since the buds for 2016 were formed in early 2015.

One grower in the room said he recently had dissected sample buds before they broke to check on their health and found 75% to 80% fruitful buds inside. Zelinski said that 80% was a good number.

But he remained concerned about the prospects: “This is a great year to have crop insurance, and most of my (client) growers do have crop insurance.”

The budding issue is not the only threat to the 2016 crop, however. Because of this winter’s early bud break, “There is every chance in the world right now to have frost damage in the next month or so,” he said.

Post-mortem on 2015
Zelinski ticked off the primary reasons for last year’s disaster:

• Salt accumulation in the root zone from four years of drought

• Primary bud necrosis (failure) from poor conditions at flowering

• Trunk and cordon diseases seemed to spread

• Vine mealybug pressure worsened, while Pacific mite pressure eased a little

• Hail damage in mid June

• High powdery mildew pressure, especially in the Templeton Gap

• A heavy rainstorm in July, totaling 2.71 inches in one day in Templeton, and encouraging Botrytis bunch rot

• The wrong trellis system in some vineyards, such as quadrilateral cordons without the vigor to support them.

California crop reporting districts 7 and 8, which cover most of the Central Coast, crushed 179,000 fewer tons of wine grapes in 2015 than in 2014. It was also an unusually early harvest but that didn’t help. Numerous growers in San Luis Obispo and Monterey counties saw yields in the 1 ton per acre range.

Zelinski recalled an insurance adjuster who went out to inspect a vineyard before harvest and told the grower there was no reason to even pick the fruit since there was so little.

In other cases a few wineries said they would pay the harvesting costs just to get more fruit. One winemaker had to pick 2.5 acres to get half a ton. Another scavenged just 2 tons from a block that would normally produce 20.

Blame it on pollen tubes
Zelinski also shared his theory about what specifically happened or failed to happen during bloom. In some cases, the flower caps stuck on and prevented pollination, but in other cases the pollen landed where they should on the flower, but they failed to successfully grow the tubes that reach down into the flower and fertilize the eggs waiting there.

He said the air temperature needs to be 80 F or above for the best pollen development, yet the bloom period in May 2015 saw very few days in the Paso Robles area hot enough. “That’s why the bloom seemed to last forever. We didn’t have many warm days when we needed them.”

What can growers do to help pollination this year? Not much, Zelinski said. He wondered out loud if towing an airblast sprayer through a vineyard during bloom would help knock the caps off the flowers, but concluded it was not a practical idea, since a grower would have to do it every day.

But he also dispelled the common superstition that growers should not even go into their vineyards during bloom. He advised the small-scale growers that the bigger outfits carry out normal vineyard chores during this time and don’t seem to suffer any bad consequences.

Zelinski concluded with the emotionally comforting but economically unsatisfying statement that, “It wasn’t your fault last year.”

(For another analysis of what went wrong with the 2015 Central Coast vintage, see the entry titled “Weather and drought effects on the poor fruit set in 2015” in the Grape Notes blog by Mark Battany, the extension viticulture advisor for San Luis Obispo and Santa Barbara counties, http://ucanr.edu/blogs/GrapeNotesBlog)

WiVi attendance grows
WiVi 2016 was the first event after Wine Business Monthly bought out partner company Precision Ag Consulting with which it co-founded the gathering in 2012. Eric Jorgensen, president of Wine Business Monthly, said attendance this year including regular registrants and exhibitors was up by 200 to 1,600.

Held at the Paso Robles Event Center, March 15-16, the conference included educational seminars with a regional focus on viticulture, winemaking and winery marketing.

The trade show packed more than 130 companies into two rooms, showcasing their new products and innovative tools, as well as winery trials tastings, networking events and other activities. In addition, WiVi unveiled a new Vineyard Automation Center that displayed vineyard-related products and services that provide automation, mechanization or new technology to help growers enhance vineyard quality. Both Wines & Vines magazine and Wine Business Monthly are owned by Wine Communications Group.

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