To celebrate this year’s Regenerative Viticulture Series, we’re releasing a roundup of each of the sessions, along with key insights. In our previous instalments we pulled together some highlights from our conversations with Mimi Casteel and Sergio Nicolau.

Our third episode was with the brilliant Mary Retallack, third generation viticulturist and agroecologist based in the Adelaide Hills, South Australia, with a particular interest in native insectary plants and their potential in biocontrol. Mary runs her own small vineyard and consultancy Retallack viticulture Pty Ltd whilst also creating and running the phenomenal Ecovineyards programme, bringing native ground covers, soil health and an agro-ecological approach to vineyards across Australia.

After studying ecology at school, Mary returned to viticulture, managing her first vineyard in 2003 where she combined her knowledge in ecology and wine growing, using native insectary plants to manage pest and disease within the vineyard. At the time this idea was perceived as quite radical, and not promoted in conventional viticulture. 

To prove the benefits of these species and encourage their use within the industry Mary decided to embark on a PHD in viticulture and plant protection. After finishing her PHD in 2019 Mary worked to share this knowledge with other viticulturalists, using funding to develop the EcoVineyards programme in conjunction with the Wine Grape Council of South Australia. This programme has since gone national, funded by Wine Australia. 

Today, Mary runs her own small vineyard & consultancy Retallack Viticulture Pty Ltd, spending most of her time on the road providing advice to wine growers, alongside running events and writing educational materials for the EcoVineyards programme.

A native insectary plant is a plant that is native to a certain region or historical plant community that provides Shelter, Nectar (food), Alternative prey and Pollen to local wildlife (encapsulated in the acronym SNAP!). These plants assist in biocontrol as they provide habitat and food for predators including arthropods, micro bats and insectivorous birds. 

Mary explains that the aim is to plant a range of species that provide habitat to a diversity of insects throughout the year. When looking at flowering insectary plants we want to grow species with a diversity of flower shapes, which have overlapping flowering periods at key times in the growing season. This is especially important during the grape flowering period to keep the inflorescences clean of pests, preventing an outbreak which could affect yields later on in the season.

In vineyards we are specifically looking at the use of ground cover and shrubs as these will work best within the wider ecosystem. Choosing species that are able to outcompete weeds, while possessing low potential to become a weed, have low establishment and maintenance costs, and low potential to host pest species.

When deciding what species to grow it is useful to look at the quality of the resources that the plants provide, in terms of nectar or pollen. Nectar is essential to provide food & energy, whereas, pollen is needed as it’s this which determines how many eggs these insects can produce, and how healthy they are. 

Mary states that diversity is key here and encourages a move away from monoculture, which she describes as a “fragile” and “poorly buffered” system in which “problem weeds and pests often dominate”, towards a polyculture system that promotes functional biodiversity, soil health, has better resilience, and is able to self regulate producing – a crop without continual intervention.

During her studies, Mary found that the capacity for biocontrol of insect pests increased more than 3x when native evergreen shrubs are planted in the vicinity of grapevines. In her experiments, Mary found that when planted concurrently shrubs like sweet bursaria (blackthorn), and prickly tea tree provide habitat for at least 65 species of predatory arthropods, including parasitic wasps, which provide biocontrol of grapevine scale and mealybugs, like light brown apple moth. 

She also studied a species called kneed wallaby grass, which is a native perennial that can be planted in the mid row or under vine and provides habitat and breeding sites for brown lacewing larvae, wolf spiders, and a range of predatory ground beetles. 

In a field trial Mary found a net increase of predator richness of around 27% when wallaby grasses were planted in combination with grapevines, including at least 37 different species of arthropods, and 100 other unidentified insect species – demonstrating the amazing richness of wildlife diversity we can get at ground level through the use of these plants!

EcoVineyards is a national programme which aims to increase the land area dedicated to functional biodiversity in and around Australian vineyards. The programme combines academic peer-reviewed research, and evidence-based learning, working with over 45 vineyards across Australia, that act as demonstration sites to trial and showcase new management practices. These sites focus on three main areas of management: soil health, ground covers, and functional biodiversity. 

Mary and the team at EcoVineyards share new knowledge learnt on these sites through the EcoVineyards website, a knowledge hub which provides resources on how to implement these practices, including: a native plant species list for different regions; soil health indicators for Australian vineyards, and a wide range of EcoGrower case studies.

They also host events and are working on creating best practice management guides for all three focus areas, providing complimentary support to EcoGrowers from regional on ground coordinators. 

The EcoVineyards programme promotes the use of ground covers instead of cover crops, encouraging a move away from the idea of annual intervention and soil disturbance towards more perennial cropping. Once this is established they move on to encouraging more diversity through cropping multispecies mixes, then working to encourage the growth of species that are naturally adapted to the site.

Mary states that the more diversity you have, the more benefits you will get in association; going on to outline some examples from the exciting research looking at the best species to plant in the under vine area, and how this affects soil health. One of these studies found that wallaby grasses and leguminous mixes with annual grasses grow well alongside grapevines, and were able to more than double the amount of soil microbial activity and sequester more carbon than systems using traditional herbicide practices. 

Mary believes there’re a lot of misconceptions in conventional viticulture including the unintended consequences of using sulphur as a fungicide. The overuse of sulphur can knock out predators like parasitic wasps and predatory mites that could provide biocontrol, while also reducing mycorrhizal fungi and earthworm populations in the soil. Mary instead suggests that during signs of a disease outbreak growers should first look towards biocontrol as a solution and use chemicals as a last resort. 

She suggests that we should be looking to instead increase the health of our vines naturally to decrease their susceptibility to pest and disease outbreaks (referred to as the trophobiosis theory). Mary explains that when our vines have a brix of 12% or more, it means that they are healthy and will more able to overcome pest pressures as “a pest starves on a healthy plant”. If growers are using sulphur Mary advises keeping applications below 400g per 100L to reduce its negative effects on wildlife populations, and the soil.

Mary believes that the economic benefits that native insectary plants and wider biodiversity provide can also help to convince practitioners and create wider industry change. We know that establishing inter-row vegetation and minimising bare earth will support mycorrhizal fungi which can in turn “provide up to 90% of plants nitrogen and phosphorus requirements”, reducing the need for artificial inputs. 

Ecovineyard’s also publish all of the financial costings of each project in the EcoGrowers case studies so that readers can see first hand how these practices can improve profitability. See the case study on Dan Falkenburg who was able to reduce his input costs and weed burden, and improve soil health and biodiversity, while saving 615$ a year by switching over from an annual cover crop to a  four species blend of self-regenerating wallaby grass.

We loved connecting with Mary and learning how she is applying an ecological approach to viticulture! Whether or not you are farming in an Australian environment, Mary’s philosophy and research can help us understand the experiments that are going on, so that we can learn from them and apply them in our own locations.

All the images in this blog were taken from the EcoVineyards website & Instagram account and Mary’s social media – follow them @ecovineyards & @retallackviti to learn more!

To celebrate our second instalment of the Regenerative Viticulture Series, we’re releasing a roundup of each of the sessions and some of our favourite insights. Last week, we pulled together some highlights from our conversation with the brilliant Mimi Casteel which you can read here. Our next conversation was with Sergio Nicolau, a leading light in the regenerative viticulture world with a deep understanding of plant and soil biology.

Sérgio Nicolau (@Sergio.grapegrower on instagram) is fifth generation regenerative viticulturist and agronomist in Portugal. Sérgio has turned his family’s vineyard from conventional to organic, and in the last few years transitioned to fully regenerative. He has had great success with his cover cropping to improve water retention, and makes his own fungal-rich compost and fish hydrolysate to improve the health of his vines as well as effectively using sap testing throughout the growing season to maximise photosynthesis and remove pest pressure. Sérgio is one part of Orgo – a group of 4 practitioners supporting others in their regenerative transitions.

One of these practices was to establish cover crops in the alleyways between the vines. Sergio takes diversity to the next level, advancing from his previous mix of 12 species from three plant families to 16 species from 6 different families including: grasses such as ryegrass and black oats; legumes including four different clovers, alfalfa and vetch; mustards, turnips, radishes, beets, spinach; and plants that will encourage pollinators such as buckwheat, calendula and phacelia.

Sergio found that changing the cover crop mix to one that is more diverse has made a big difference to his soil health. Before implementing cover crops the vineyard experienced issues with soil runoff during periods of heavy rainfall. Cover reduces this through slowing down the individual rain droplets, intercepting them before they hit the soil; while the roots act as an anchor, holding soil aggregates in place, reducing erosion and nutrient loss. A diversity in root architecture enhances these benefits as it allows for more layers of soil to be penetrated, improving structure through breaking up compaction layers and opening up pores in the soil allowing water to infiltrate more effectively. 

Sergio also uses his neighbours sheep to graze his covers during winter when the vines are dormant using holistic planned grazing practices. This maintains the growth of his cover crops, while improving soil and vine health by introducing a source of organic matter and nutrients through the sheep manure.

Sugars go to three main points in a plant: the shoot tips, fruit and the excess goes to the roots. Meaning the higher your photosynthetic capacity the more root exudates are released into the soil, feeding the biology within it. Diversity is key here for a few reasons, firstly diverse mixes will grow plants of varying heights with different leaf sizes and shapes that can capture more sunlight at all levels. Secondly, “the more varied your species, the more varied your root exudates – different plants feed different biology and it’s this diversity that is important”. 

Sergio also discussed the effect different plant species have on the redox potential of the soil, creating either disease suppressive or disease enhancing soils. Some plants are more oxidative, such as GMO (modified species), whilst species such as clovers, black oats or mustard are more reductive. He states that it is good to experiment with a diverse range of covers in order to find out which species work in your system: “Now I have learned enough to know that the next mix will be different and maybe I do not have to grow as many species, just the right ones”.

It is amazing to see that despite being in very arid conditions the ground cover in Sergio’s vineyard is extremely healthy, green and lush! A testament to his management.

It is believed that nutrition is a key factor to plant immunity, the more balanced nutrition a plant has the more resilient they become to pests and diseases. It was during an insect attack on his vines that Sergio really saw the power of increased nutrition. Being certified organic meant Sergio was compelled to search for alternative approaches to the use of insecticides. He found that insects have simple digestive tracts and cannot digest complex proteins or amino acids. If you increase the presence of these compounds within a plant insects will stop seeing it as a food source. He found that molybdenum is a cofactor for the enzyme that reduces nitrates and allows nitrogen to form amino acids and complete proteins. After applying a spray of molybdenum, magnesium and sulphur, Sergio found that within two days the insects were no longer feeding on the vines having moved on to the weeds instead!

Sergio now regularly measures the nutritional makeup of his plants using sap analysis in order to decide what nutrients to apply in his vineyard. This is not only useful to get a sense of the vines health and the extra help they may need, but also for understanding what sprays he should cut back on in order to improve nutrition. An excess of some nutrients may have an undesired affect, for example high levels of potassium will block other nutrients such as calcium and magnesium. While other nutrients will have a positive relationship with each other, meaning you may only have to apply one to get an increase in three nutrients. Sergio believes it is very important to understand these synergies in order to be efficient and economic with your applications.

Abby and Sergio discussed that although sap testing is often just a snapshot in time, the idea is that you’re improving the plants health in that moment, in turn increasing it’s photosynthetic capacity and its ability to feed soil biology. This will support the development of a healthy soil ecosystem, promoting long term health and resilience and reducing the need to apply these artificial foliar nutrients in the future.

Sergio has stopped buying commercial products of micronutrients in their oxidised form as he believes the plants will not be able to neutralise them as well. He instead does his own chelation at home using the raw nutrient mixed with a carbon source such as fulvic acid, molasses and seaweed to make nutrient extracts. 

He also produces additional extracts using more natural ingredients including seaweed, which is high in nutrients and provides beneficial hormones for the plants; plant extracts such as horsetail extract which is rich in silicon and fights fungal disease through drying out the leaves; and shrimp extract which helps boost plant immunity, furthering its resilience against disease. Sergio also discussed his use of fish hydrolysis within the vineyard which provides protein and organic nitrogen to the vines themself, while also supplying a good source of healthy fats which feed the fungal communities within the soil. 

Sergio uses two separate extraction methods to produce fish hydrolysis: when used as a soil fertiliser he will shred the fish waste and mix it with water, molasses and lactic acid; when aiming to create a foliar for the leaves he uses Korean Natural Farming techniques: mixing equal weights of fish waste and brown sugar. 

Abby and Sergio moved on to discuss the importance of building soils that are more fungal dominated in vineyards. Years of using conventional tillage and chemical fertilisers has decreased the fungal communities within Sergio’s soil, leaving it dominated by bacteria. To combat this Sergio uses both fish hydrolysis alongside a compost extract made using the Johnson-Su technique. Johnson-Su composting aims to grow a biologically diverse soil microbiome that is fungal dominated and applied to the soil as a microbial inoculant in the form of a liquid fertiliser. Sergio applies this in his vineyard using a sprayer and mixes in fish hydrolysis, humic acid and micro nutrients to act as food for the biology in his compost extract, “sending out the biology with a lunch box”.

The benefits of the use of these nutrient extracts coupled with the regular monitoring Sergio’s is performing is shown through the brix level of his vines. The first year he started applying nutrition more seriously the brix of his vines measured at 4-6%, and has increased to a brix level of 17-21% measured just before last year’s harvest. Considering the ideal brix level for healthy and resilient vines is 12%, this is truly an incredible result for Sergio!

Finally, Sergio discusses how transitioning to these regenerative practices has affected his vineyards finances. During the three years of organic conversion Sergio did not experience any improvements financially, as while he was spending less on inputs he also experienced a reduction in yield from weaning his vines off of relying on chemical fertilisers, and through his conversion to a vine species that produces less but higher quality fruit. However, now out of his conversion period Sergio is able to sell his grapes at three times the price and is now producing his own wine, adding value to his business. These changes in management practices have decreased his cost of production and increased his economic return. 

It was great to catch up with Sergio and discuss his practical and innovative approach to vineyard management. If you want to learn more about how Sergio implements these regenerative practices in his vineyard, listen to the full conversation in the video below!

All of the beautiful images in this blog were taken from Sergio’s Instagram account – follow him at @sergio.grapegrower for more insights.

To celebrate our second instalment of the Regenerative Viticulture Series, we’re releasing a roundup of each of the sessions, along with some of our favourite insights. Here we’ve pulled together some highlights from our conversation with the brilliant Mimi Casteel, vineyard manager & winemaker at Hope Well Wine, Oregon.

Mimi Casteel is a vineyard manager & winemaker at Hope Well Wine in Oregon. Mimi’s experiments at Hope Well are rooted in creating beautifully regenerative, biodiverse & resilient ecosystems with the vines. Mimi is also a trustee of The Regenerative Viticulture Foundation, a global non-profit aiming to support a transition to more agro-ecological practices in wine-growing, which enhance soil health and biodiversity.

Growing up on her parents vineyard and winery, Bethel Heights Vineyard, was formative for Mimi; she strongly connected to the surrounding forests, going on to study a masters in forest science, eventually working as a botanist and ecologist for the US forest Service.

In 2005 Mimi came back to farming and viticulture out of a desire to help make changes on private land, where she felt the true threats to the US native ecosystems were occurring. In 2021 Mimi and her family moved from their previous 80 acre site (30 under vine) to a smaller plot of land. Downsizing released Mimi from the business of selling grapes to other winemakers, and allowed her the opportunity to work in other types of agriculture with practitioners looking to start on a regenerative path. 

Moving away from producing grapes commercially and growing only for her own wine also gave Mimi the freedom to experiment with different regenerative practices herself; exploring how restoring and enhancing natural systems can support nature recovery and develop character in the wine. 

Mimi’s background in forestry has given her a unique approach to viticulture and has influenced her management decisions in interesting ways. She has a particular focus on the different dimensions in a vineyard, exploring how encouraging a wider range of natural architecture, such as shrubs and trees, can benefit the farm ecosystem both above and below ground, much like the varying layers of habitat within a forest.

In the first year at the new site, Mimi allowed herself the space to just observe what was happening on the land – noting what native seedlings were emerging, where, and allowing them to grow. 

This year she is looking to install some more wildlife architecture, particularly around the edges to add structural diversity alongside providing wind buffers, wildlife cover, food and forage. Aiming to create a “multidimensional geometry of symbiosis” through using native shrubs and trees to vary root structures with perennial grasses. Mimi is interested in how these different levels of architecture can reduce a farming system’s dependency on outside inputs to protect the crops that are being grown.

One major benefit of introducing large ecological features such as trees is the effect that their root systems will have on the underground network. In the first decade of its life, a tree will put all of its photosynthetic energy into its root system, and it is that root architecture which often determines the depths of the water table.

This not only affects the resilience of your vineyard but has the capacity to contribute towards drought resilience on a regional basis. 

Mimi believes in starting with the “biggest architectural features that you want to bring back” and then “dialling in the details after that”. “You need a big base to have a tall pyramid!” – through her experiments over the years she has found that “you can’t spend too much time building the base of that pyramid – the bigger it is, and the stronger it is, the higher you can go with whatever else you want to do”.  This is also important for minimising the potential for competition between this larger architecture and our vines. 

Disease pressure is a limitation for most viticulturalists. At Hope Well they have very wet springs and winters, creating significant powdery mildew pressure.

Mimi is exploring combatting powdery mildew without using chemical fungicides. She has found that the vineyard floor affects the humidity of the fruiting zone and the amount of water available at each point in the growing season. Cover crops will provide a buffer in the event of heavy rainfall late in the season. If cover is established it will absorb the water in place of the vines, reducing the likelihood of “blowing up” the fruit due to excess water uptake, reducing the risk of botrytis. Mimi has also been experimenting with cover crops under the vine itself; observing how the vines respond, how long the flowering period is and when they start to senesce, especially during the grapes ripening stage. 

In Mimi’s experience, vineyards are most vulnerable to fungal diseases when vines are growing the fastest. She likens the beginning of the growing season to when you clear cut a forest – there is an abundance of nutrients and moisture and the plants are eager to grow and grow quickly, resulting in large, water swollen cells that lack a certain level of structural integrity. Mimi therefore prefers less internode growth during this period, instead encouraging growth of small, lipid dense cell membranes to hopefully result in a higher density of nutrients and photosynthetic products staying within the cells, to increase the vines’ resilience against disease. Cover crops can help manage this period of extensive vegetative growth by absorbing some of the resources that would otherwise be used by the vines. 

Mimi’s region in Oregon tends towards an arid climate in summer, susceptible to drought, such as during the 2021 “heat dome” where temperatures were regularly recorded at over 46 degrees celcius. During this period Mimi measured the soil temperature on her own (un-tilled) land, compared with the soil temperature on a neighbour’s tilled fields. She found that her soils were as much as 15 degrees (Celcius) cooler than the tilled soils, a difference which affects drought resilience as well as the biological life the soil is able to support. 

Mimi also discovered that the vine canopies were degrees cooler in her vineyard, due to the presence of cover crops holding water in the soil, and enabling transpiration to occur. She also found that her cover crops were reducing the likelihood of frost damage during the winter – the covers held heat within the soil, so they stayed warmer for longer, and were not affected by frost until much later into the winter season. 

Mimi’s incredible findings represent powerful examples of the benefits of continual cover and living roots within the soil.

While many ecological and economic benefits of using regenerative practices in vineyards are clear, we appreciate it can still be daunting to begin the transition. We asked Mimi how she began her transition and what advice she would give to others taking their first steps on a regenerative journey:

We loved having the opportunity to talk with Mimi who has inspired us to look at viticulture and a vineyards ecosystem from a new perspective. If you want to learn more about Mimi’s regenerative journey listen to the full conversation in the video embedded at the beginning of this article.

All of the beautiful images in this blog were taken from Mimi’s website and Instagram account @mimicasteel – check them out to learn more about Mimi’s philosophy at Hope Well.