by Thomas Grandperrin
Published on June 17, 2022
This article was initially published in The Wine Industry Advisor.
Field scouting is a fundamental component of a successful integrated pest management (IPM) program, yet it’s also one that calls for significant time investment. Because of this, many growers I’ve had a chance to talk to in the past few years (including Greg Gonzalez, David Gates and Caine Thompson) have alluded to the overbearing importance of training vineyard crews on pest and disease scouting. To delve into the reasons and benefits of initiating such a training, I spoke to Mauro Maldonado who underwent this process just recently.
Maldonado is viticulturist of Ridge Vineyards’ 300-acre Lytton Springs Estate in Healdsburg, Calif. While he started in March 2020 as a viticulturist, Maldonado actually started working with Ridge in 2011 when he was still in high school. “I was working with the vineyard crew, doing things like shoot thinning and fruit thinning during the summer,” he says.
Maura Maldonado scouting for pests
Maldonado’s current day-to-day responsibilities include supervising the farm labor contractor crew’s work and ensuring the vineyards are farmed according to Ridge’s specified quality standards. As a certified pest control advisor (PCA), he’s also responsible for enacting the company’s integrated pest management program.
Enhance field workers’ knowledge
In the past, pest monitoring at Ridge was carried out by the (previous) viticulturist and by interns that were hired every year. But, based on his own experience working as part of the vineyard crew, Maldonado realized, “the field workers really knew where the hotspots were for certain things.
“For example,” he continues, “they always knew where to start looking for powdery mildew, even if they didn’t completely understand the pest. They’re out there every single day, going through every single vine multiple times throughout the year.”
Maldonado knew, right off the bat when he started working as a viticulturist, that the field workers would be his go-to when it came to pest scouting, and their feedback was going to be one of the most important tools to quickly identify troublesome spots. “It’s difficult to monitor your vineyard properly when you have 300 acres and have other tasks to do,” he says. “Keep in mind that your crew members can potentially help you out. That’s what made me want to give them more in-depth training.”
For example, the vine mealybug (VMB) transforms in appearance at distinct stages of its life and can also be found on different parts of the vine as the seasons change. Maldonado noticed his crew was aware of vine mealybugs but didn’t know exactly how to scout for them, or what they looked like at different life stages.
“They were assuming that [the bug] was always in the canopy and in its adult form like those big white fluffy insects we’re all so familiar with,” he says. “It was crucial to make them understand that, for instance, they’re not going to see the pest in the winter on the vine because it’s hiding under the trunk or right beneath the soil.”
Show them the problem
Maldonado compiled his findings in a PowerPoint presentation, in both English and Spanish, with an emphasis on vine mealybug. He included pictures and videos of the bug at different stages of its life cycle. While female vine mealybugs were the prime subject, Mauro also addressed the topic of male vine mealybugs, “So [the crew] could understand that male and female mealybugs look very different, and it’s very important to control both of them,” he says.
Explaining how VMB moves during the season and how to scout for them during the different vine phenological stages is key. “We started off in the winter, when VMB hides under the bark or right under the soil,” Maldonado says. “Then, I showed them how we are using pheromones to attract the males in the Delta traps, starting from bud break, to figure out when the flights occur. That information will trigger the use of pheromone mating disruption.
“Then, I explained that crawlers are starting to move up the vine. The vineyard crew can start looking for signs of VMB presence: more bleeding out of the trunk and the presence of ants. As the season progresses, especially around veraison, VMB moves farther into the canopy — sometimes into the cluster — until harvest.”
At the end of his presentation, Mauro showed samples of different life stages of VMB he had collected in the vineyard, including an egg sac, crawlers and adults.
Ridge Vineyards’ intern, Ryan Brennan, checking on an ant bait station
“Showing the team an actual sample helped a lot,” he says. “They realized, for instance, that they were always focusing on adults and had never really paid attention to the crawlers.”
As part of its IPM program, the Ridge Vineyards’ team releases Cryptolaemus beetles and Anagyrus parasitic wasps for the control of VMB as well as predatory mites for the control of spider mites. Chrissie Davis of Koppert, one of the company’s main suppliers of beneficial insects, brought some samples of each species to Maldonado’s presentation.
“Thanks to the incorporation of the different materials, everything went smoothly. [The presentation] let the crew really understand and recognize the different stages of the vine mealybug and its natural enemies,” says Maldonado.
A quick payoff
“When I started in this position in March 2020, I knew vine mealybugs were present, based on the notes left by the previous viticulturist,” says Maldonado, “but I quickly realized even they weren’t aware of how bad the infestation was in some areas.”
He explains that, “The week after my presentation, the vineyard crew started to report new vine mealybug hotspots. I wouldn’t have been aware of those if I had just been scouting by myself and with the interns.
“That was when I realized the training had worked.”
Input from his newly educated crew helped him really understand what was going on in different blocks and develop a more effective IPM plan, especially for the release of beneficial insects.
In 2021, Maldonado had the opportunity to include his vineyard crew when releasing the beneficial insects. It helped, he says, that they could see the whole process. “We went back together to the blocks where we released the Cryptolaemus larva to see if the pest population was getting cleaned up or not,” he adds.
He admits that finding downtime to involve the crew in this type of activity is “a little hard right now because of the labor shortage. Using drones to release the Cryptolaemus beetles could help a lot, especially when we need to apply them in an entire block.”
Red blotch virus and spider mites
Mauro is now preparing a presentation on viruses, specifically red blotch, which can affect wine quality. “We rely more on the interns when scouting for red blotch, since the crew is already swamped with harvest. I think it will be useful for [the vineyard crew] to understand how [the virus] works and why it’s important to deal with it. ”
His presentation explains that the viral symptoms show differently in different grape varieties, so he first tests a suspected vine to make sure it’s positive for red blotch. Then the intern flags the infected vine so the vineyard crew can pull it out in the winter.
“The problem is, vines with red blotch can look healthy in the winter when they have no leaves,” says Maldonado. “I noticed that sometimes, as crew members are about to pull a vine, they hesitate and skip it because they see it with healthy-looking canes. That’s why it’s important to tell the crew more about what red blotch is.”
He also plans to conduct a presentation on spider mites.
“We usually don’t see too much pressure from spider mites. But last year, it was very dry because of the drought. We also did a little more disking to try to reduce the three-cornered alfalfa hopper [insect], that can vector the red blotch, and to relieve a little more competition from weeds. That created more dust, which let us see a little bit of a spider mite flare-up in some blocks.”
Don’t underestimate your vineyard crew
Maldonado urges his fellow viticulturists not to sell their vineyard crew short. “Teaching them these topics is not going to take a lot of your time and you’re going to get a lot of benefits,” he says. “You can do this training in the winter, when it’s raining or when the crew can’t go out and work.
“They’ll also appreciate that you are taking the time to teach them a new skill.”
He deems this level of involvement necessary for all activities, not just when it comes to pest scouting. “If you’re explaining to them why you’re going to shoot thin a certain way or why you’re going to leave fewer buds during pruning, they’ll have a much easier time carrying out these activities if you give them a reason for each action, not just a task to do,” he says.
He then underscores that this applies especially to the most seasoned people in the crew: “If they’ve been doing [something] one way for many years, it’s going to be hard to change that mindset unless you give them a good reason for why you’re making those changes.” Old dogs, new tricks.
“No matter your title, position, or seniority, everyone wants to feel a sense of belonging when they work for a company,” he concludes. “By including everyone in your thought process and taking in feedback, you can help achieve that sense of belonging. In turn, you’ll have a crew that’s well rounded, values the work that they do and appreciates your trust in them.”
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A discussion with Michael Gilbert, founder and CEO of Semios on how forecast pest models help IPM planners rely less on pesticides.
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A discussion with David Gates of Ridge Vineyards on how pest pressure varies according to the location and variety of the vine, beneficial insects he has used in his vineyards, and some of the cultural practices he implemented to limit pest pressure.
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