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By November 26, 2018 0 Comments Read More →

Clean Wood: The Multi-Faceted Processes for Keeping Disease-Free Vineyards

By Dawn Dolan

According to the State of The Wine Industry 2018 report, the wine industry has been in a 20-year growth pattern. Questioning how to maintain this growth is apropos. Some of the practices growers are leveraging today are becoming outdated and will slowly prove imperfect for today’s needs and pressures. The report also ventures that successful wineries in the future will be those that adapted to different consumer trends and operational practices.

Let’s say that you suspect that some of your vineyard is diseased, and you are pondering the options. Easiest of the options probably follows this course: Send it to UC-Davis for testing, rogue and rip out the offenders you see, and maybe the vines on either side; buy clean wood or grafts, and replant. With this choice, you are aware that other parts of the vineyard will probably show up with the disease, and those new vines you just planted may, or may not, hold out longer than your older vines.

Red blotch infected leaves

Another common scenario to ponder: You have a new vineyard area to plant or re-plant, and you want to be absolutely certain that no trace of disease comes in with the new plantings, nor is left from the previous vineyard. Trusting that you are buying clean vines from your provider, you make your order and cross your fingers.

These processes are changing, with farmers pushing for better and multi-pronged approaches to keeping their vineyards clean. They are not excited about the idea of replacing their vines every 15 years instead of every 30, or hoping that in receiving a new order, they get 96% of the vines clean, yet not expecting that all will be.

First Steps

Foundation Plant Services (FPS), which is run by UC-Davis, is the first step in the cleaning process. Director Deborah Golino pointed to their website, where they have information on their custom laboratory testing services. “Disease testing services using polymerase chain reaction (PCR) technology is available at FPS for 16 pathogens of grapes and 5 pathogens of fruit and nut trees. PCR is a highly sensitive test that has been optimized at FPS for both grape and tree pathogens.”

All vines planted in the 100-acre Foundation Vineyard go through this testing (as well as testing by California Department of Food and Agriculture) after two years, and that continues if any trace of disease is found. One core tenant of FPS is to produce, test, maintain and distribute elite disease-tested plant propagation material, and undoubtedly this process has worked towards their goal to help reduce the incidence of diseased vineyards. This program operates not just for grapes, but also for prunes, pistachios, strawberries, roses and sweet potatoes.

Monitoring Vineyards and Working with Neighbors 

An October 23rd, 2018 article by Ted Rieger in WineBusiness.com discusses the Lodi Wine Grape Commission’s recent “leafroll virus tailgate talk and field day”, with a UC-Davis research entomologist there to discuss the “three-cornered alfalfa hopper (3CAH), identified in 2016 as a vector of grapevine red blotch virus.”  Keeping tabs on the affected areas as well as the critters in your vineyard and in your neighbors’ vineyards is one tool not enough are engaging in. As reported by Rieger, “Lange Twins vineyard operations manager Aaron Lange has been a major proponent of regional virus management and outreach in the Lodi area, and for growers statewide. Lange explained: “This is absolutely a grower community issue, and we all need to be on the same page. We don’t want to allow a large source of virus inoculum to exist out there that can be transmitted to other vineyards. I think we’re way behind in what we need to know to properly manage this issue.”

The article mentions that “Trinchero Family Estates (TFE), also uses trained scouting crews to identify infected vines with red leaves and has achieved about 75 percent accuracy with verification by lab tests.” Scouting crews, savvy neighbors, and NDVI or aerial photography could all help with the identification of area manifesting with red blotch, for example. A program that the California Association of Winegrape Growers (CAWG) hopes to offer grower groups could help educate grower groups in identification practices, offers.

Futuristic Options

Curt Granger, vice president of global sales for grapes at Phytelligence, wants growers to look further. He concurs that the biggest trend that has happened over the last 10 years on the nursery side of the wine grape business is that there is a clean plant network, where you source your clean stock for grapes and other nursery plants. However, he states that the traditional nursery process, “takes clean material and puts them back outside. When you introduce clean rootstock and scion wood back out into the environment, it’s an opportunity for virus and disease reinfection.” He says their objective is to take it ’inside,’ thus keeping the wood true to type, with the right rootstock, and virus and disease free. He says that Phytelligence takes clean source wood out of UC-Davis, and rechecks for all viruses. Granger says they optimize four specific growth phase production gels that allow them to “spin that up in quick fashion depending on order, rootstock, self-rooted or grafted vine production and then transfer to controlled, indoor environment, where their system allows no chance of reinfection.”

Trellis Changes

Granger feels that changing how a vineyard is planted, with new vine products and formats will save labor costs for vine training and suckering. The newer 24” and 35” higher grafted formats reduce training establishment costs, suckering and time to cordon arm establishment. From Phytelligence, because their vines are generated from plant tissue culture and not propagated cuttings, they use field budding techniques that will eliminate future suckers produce by bench-grafting machines. “When you look at suckering and thinning costs on a standard bare-root dormant vine, a lot of that work is low to the ground at the graft union.  This allows for a production shift and cost savings in a diminishing labor market,” says Granger. “It gets to the wire faster, which allows for earlier spraying and saves labor.”

CAWG will be reviewing a Best Management Practices document in November that they hope to make public once approved, cites Rieger. Whatever approach is used, using the strategy of a multi-pronged approach to disease management in the vineyard need not be overly pricey or time-consuming. It’s clear that for future success, diligence is required to keep pests to a minimum.

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