by Thomas Grandperrin

Published on March 1, 2022

This article was initially published in The Grapevine Magazine.


Regenerative agriculture has been one of the most discussed trends of the past few years. Still, the thought of transitioning from a conventionally managed vineyard to a regenerative one can be intimidating. A few of the reasons it is so daunting are that the risks of change are perceived to be extremely high, the rewards seem to be vaguely defined, and the process is not particularly well known within the industry. However, each of those concerns is addressable with a bit of research, so we decided to speak to someone who not only has done that research but became convinced that the transition was the right choice. 


Meet Caine Thompson, managing director of Robert Hall Winery and sustainability lead for parent company, O’Neill Vintners & Distillers.

Vine mealybug infestation on a grape cluster

Caine Thompson, managing director of Robert Hall Winery 

All of Robert Hall Winery’s estate vineyards and the external growers supplying the winery already follow California Sustainable Winegrowing Alliance (CSWA) guidelines. Transitioning to organic regenerative viticulture felt like the natural next step for the company, which started a regenerative and biodynamic trial on its estate vineyards in late 2020. The goals of this study are to understand what effects these practices have on yield, costs, overall fruit and wine quality, but also share the lessons learned along the way.



The main difference between regenerative organic certification and organic is the focus on the beneficial ecological and social outcomes. One of the three main objectives is to build soil organic matter to improve yield without the need for synthetic inputs while sequestering carbon as a way to fight climate change. 


It also evaluates the social components of farming. “Without the people working in the vineyard, we wouldn’t have much of an industry. Looking after employees, giving them access to anything they need, and paying a living wage over a minimum wage is a big piece of the regenerative movement that no other certification really talks about.


The third pillar of regenerative farming is animal welfare and using them to replace machines when possible. For example using sheep at the tail end of harvest to: clean up the weeds and cover crops, recirculate nutrients back in through manure and reduce the overwintering detrimental spores of disease. 



In 2020, Robert Hall initiated a multi-year trial of new tactics designed to profitably achieve regenerative and biodynamic certification in 43 acres of their Paso Robles estate vineyards’ 130 acres. The remaining 87 acres are still farmed under the sustainable guidelines and serve as control during the study.

Vine mealybugs on a grape vine cane
Robert Hall’s estate vineyards


The vineyard management – pruning, shoot thinning, wire lifting, etc. – is exactly the same in both blocks. The study compares multiple metrics in the control and trial blocks on an ongoing basis.


We took some base level samples at the start of the study, and will keep performing tests over the next three years to assess the evolution.” 


Measuring the impact of the new practices on soil health is one of the most important aspects of the trial because improved soil health can lead to improved yields as well as reduce input costs.


We’re measuring soil organic carbon levels and the various elements within soil.” 


Caine shares, “We put six tons to the acre of compost on the vineyard at the start of the trial. With the beneficial cover crops that are going in, it’s going to build organic matter and create a living soil. Soil can take a long time to change, but I feel like we’re making progress.” 


Caine explains how the impact of improved soil health on grape characteristics is measured. “We’re doing fruit analysis at the time of harvest, including bricks, pH, titratable acidity, yield, phenolics, and yeast assimilable nitrogen levels.”


The changes resulting from the implementation of regenerative and biodynamic practices don’t stop in the vineyards. Caine comments that, “The idea is to take fruits from the regenerative block and bring them through the winemaking process with very minimal adds. For example, we’re using native yeast instead of conventional yeast.”


Robert Hall is tracking the costs of these new practices as well as what bottles the grapes in the trial end up filling, so when the wine is sold they will be able to calculate their marginal profit generated from regenerative management.   



Completely stripping out fertigation, herbicides, conventional-based products, and starting farming under a regenerative mindset is a big change to the vineyard ecosystem. The benefits are often only noticeable in the second or third year.


However, Caine claims “We’re really encouraged by the results in terms of how the fruit came in, how the wine quality is looking, especially for year one in the conversion.


He details that “There was a noticeable difference in fruit quality that we think is purely attributed to a larger canopy. The sustainable lot had a smaller canopy, with more sunlight going on the berries, provoking more dehydration. This reduces yield and tends to give the grape an overripe ‘jammy’ character. Whereas on the regenerative side, there was more shade and grapes were definitely less shrivelled.” 

Mark Hoddle in Pakistan collecting Tamarixia radiata, a natural enemy of Asian citrus psyllid, Diaphorina citri.

Left: smaller canopy in the sustainable vineyard.


Right: larger canopy in the regenerative vineyard.

On the wine-making side, “Fermentations looked good. They went through quickly, the native yeast was healthy and we didn’t have a problem with any of the ferments.” 


On a social aspect, Caine claims that “The staff working in the vineyards takes a high level of care because they feel like they are contributing to something that’s kind of larger. It’s great to see that level of commitment in the vineyard team. It’s one of the elements that I continue to be surprised about.


The economic data will be published before spring and should “help guide some decisions of where to go next season.



A hesitancy to rely solely on non-conventional pest management is a strong barrier to the adoption of organic viticulture. However, there are proven strategies for managing many of the most significant pests. For example, vine mealybug (VMB) is currently the most significant pest in California vineyards. It transmits the very destructive leafroll-associated virus type III which can spread very rapidly within an entire vineyard if a monitoring and control program is not put in place. 


Once you do see the virus, it’s important to map its spread within your vineyard. We place identifying poles next to the infected vine, and then remove it to stop the spread,” explain Caine. 


While removing and replacing vines is a significant upfront cost, Caine believes VMB poses a greater long-term threat. “If we want to be a great wine region in Paso Robles, vine age is going to be what gets us to greatness. We need to ensure that vines don’t suffer from the onset of leafroll virus.


As part of their transition, the team at Robert Hall stopped using conventional insecticides. After investigating different options, they chose augmentative biocontrol as their main strategy to control VMB.


We started working with UAV-IQ, which offers a service called BioDrop. They release beneficial insects in vineyards using drone technologies. They helped us identify Cryptolaemus, aka mealybug destroyer, as the predator of choice to target mealybugs in our vineyard. It’s a ladybird beetle which, at a larvae stage, looks very similar to a mealybug.

Mark Hoddle in Pakistan collecting Tamarixia radiata, a natural enemy of Asian citrus psyllid, Diaphorina citri.

Small but voracious: The mealybug destroyer’s larvae


The speed of the releases and solving labor-shortage issues are not the only advantages of using this release technology. “Using drones, you minimize the soil compaction caused by tractors. It’s pretty amazing seeing drones fly and drop predators throughout your property.

Mark Hoddle in Pakistan collecting Tamarixia radiata, a natural enemy of Asian citrus psyllid, Diaphorina citri.

BioDrop’s drone, ready to take off

Caine is pleased with the results, as “It achieved the same level of control as any other conventional based program that we’re running.


He explains that they currently don’t have any other significant pests that they need to control but mentions that “It’s nice to know that whatever pest does emerge, we’ve got a partner like UAV-IQ to help solve that problem with biocontrol and integrate it in our existing program.



Releasing beneficial insects is part of a larger plan to improve pest management without pesticides. “We are trying to build a more diverse ecosystem, adding more shelter and food sources to attract and retain natural enemies in the vineyard.


Caine reports “We planted mixed species of oats, legumes, and flowering plants as cover crops just before the rain came at the end of 2021, so it should perform really well.” He emphasized the importance of choosing the correct species for local conditions. “It gets so dry in California that you’ll want to plant a cover crop that can grow on a small amount of water.


Growers can also use different compost teas and biodynamic preparations to build healthier soil and vines that will be less prone to pests and disease attacks. While creating a perfect balance where vines don’t attract any pests is the “holy grail”, Caine believes that getting there is not necessarily reachable. “There are always external factors provoking mealybug outbreaks. What I’ve personally learned in agriculture is that every season is different and the environment is always changing.” 


With that in mind, Caine emphasizes that complete pest eradication shouldn’t be the main objective anyway. “The goal is to build a more biologically diverse vineyard and create a balance where predators will prevent mealybugs from reaching outbreak levels, slowing down the spread of leafroll virus.


As for preventing fungal diseases like botrytis, Caine believes that cultural management, detailed pruning to a balanced vine, practicing shoot thinning in order to have an open canopy, and checking that bunches are not intertwined, can go a long way. 


As an industry veteran, he understands well the potential impact an issue in the vineyard can have on the long-term success of a winery. “The grapes we are growing turn into a bottle of wine, that turns into a brand that goes into our customers’ hands. So it’s important that we’re consistently delivering that wine to our customers. Having a reliable IPM and biocontrol toolkit that’s built for regenerative farming is going to be part of ensuring brand quality over time and helps de-risk this form of growing.



One of the main goals of Robert Hall’s regenerative study is to share their experience with other growers so they can learn from their successes and failures.


Caine acknowledges that large wine companies which have access to vineyards in different areas like O’Neill does, are often better able to set up trials than small growers are. “For a five-acre grower, setting up a trial in the entire vineyard is a lot of eggs in the same basket.


But that shouldn’t prevent them from starting to make changes on a small scale. He suggests that “You can stop using herbicide on a few roads, plant some cover crops on five rows and see what happens, or only apply sulfur instead of all the other products for powdery control, just on one block.” 


When talented conventional growers have been farming in a particular way for 10, 20, 30 years, they need to build trust in new ways of growing.  


If there is an interest, anybody can start small, get the learning, build the confidence and then in time, bring that to the rest of the vineyard.” 


Field days are organized on a regular basis at Robert Hall Winery, where growers, industry stakeholders, and consumers are invited to learn from their experience.


We’re happy to share what we’ve learned along the way with other growers who want to come down this path.



While achieving regenerative organic and biodynamic certifications can help meet the increasing customer demand and secure a premium bottle price, Caine believes the transition is the right thing to do for more than economic reasons. 


We need to remove harmful chemicals and farm in a way that regenerates our soils for the future generations. If we keep farming the way we currently are, we are going to find ourselves experiencing other problems in the future.


To conclude our conversation, Caine shares that people within O’Neill Vintners & Distillers rally behind this transition to regenerative viticulture. “It’s pretty amazing to be able to work for a company that produces great wine while having a positive environmental and social impact.


Readers, are you interested in starting the transition to regenerative agriculture? Make sure to attend upcoming field days at Robert Hall Winery and reach out to UAV-IQ.

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