Vineyard Field Day at Paicines Ranch

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In early June, farmers and others came together to learn about Paicines Ranch’s nature-based solutions to pest management in their San Benito County vineyard. Using a holistic, ecological lens, they are growing taller vines with larger canopies and a vineyard floor covered with plants that are periodically grazed with sheep. To continually fine-tune their approach, they and partner researchers assess natural enemy and pest insect numbers, and plant and soil health.  

Pest control is occurring at the Paicines vineyard without the use of pesticides. 

Stewarding and Monitoring at Paicines Ranch – Kelly Mulville (Paicines Ranch) discussed vineyard stewardship and how with the right conditions, the vineyard floor is flourishing with 58 plant species, including the native milkweed so important to Monarch Butterflies. The ranch also supports 68 bird species, including the rare Tri-colored Blackbird. There are so many spiders that they had to purchase special irrigation parts to keep the arthropods from plugging up the system. Greg Richardson (Paicines Ranch) covered research and monitoring. One of their partner researchers from UCSC studied the presence of insects on the ranch and in a nearby conventionally managed vineyard (the control). There were twice as many parasitoid insects and three times as many predatory insects as in the control. Meanwhile, the numbers of pests - the sapsucking and herbivorous insects - were at the same levels in both vineyards, showing that pest control is occurring at the Paicines vineyard without the use of pesticides.

Tommy Fenster sweeping the field for insects

Grazing the Tall Vines Brings Added Value – Kelly Mulvile and Tommy Fenster (PhD Student with UC Davis and the Ecdysis Foundation) discussed how with a tall trellis system that only allows the sheep to browse the suckers and shoot tips, labor costs are reduced and the sheep leave urine which is high in valued potassium. The ground cover contains both grasses and broadleaf species. The sheep tend to eat the broadleaf plants first and trample the grasses. These grasses initially provide refuge for beneficial arthropods such as spiders, predatory mites and beetles, and reduce the evaporation of water from the soil surface. As they break down, they also add carbon to the soil which increases the microbial diversity, soil aggregation and water holding capacity.

Sheep Grazing Vineyard
Sheep grazing the vineyard. Photo: Anne Hamersky

Planting Natives – Sam Earnshaw (Hedgerows Unlimited) and Greg Richardson led a native planting demonstration along the row-ends of the vineyard and discussed how other natives were being planted in missing vine locations. Conservation plantings provide many benefits including supporting natural enemy insects, birds and bats, and pollinators. The plantings also increase soil health, water retention and soil carbon and enhance aesthetics. Sam shared techniques for installing plants, as well as the long term maintenance and irrigation requirements.      

Planting Natives

Providing What Birds Need to Be More Beneficial Jo Ann Baumgartner (WFA) discussed how the vineyard with a diverse understory of grasses and forbs and a diverse surrounding landscape of grasslands, oak savanna and riparian areas supports a diverse community of birds that provide more pest control benefits. Nick Filannino (WFA) showed the different features of nest boxes and how to mount them safely using T-posts, conduit poles or vineyard trellises, and adding a baffle guard when necessary. He also showed how a curved metal rod can be attached to a nest box and hung in a tree safely.

Cover crops support many native bees and especially spiders - they have been found to comprise 90% of the arthropods in some vineyards!

Supporting Biological Control with Habitat Diversification: The Devil is in the Details – Houston Wilson (UC Riverside) shared that while increasing biodiversity generally increases ecosystem functions, many outcomes are specific to the crop system. Landscape diversity proved the most important factor in supporting beneficial wasp parasitoid Anagrus spp. which attack the Western Grape Leafhopper in wine grapes. Coyote brush in particular is good at providing overwintering habitat. Areas with increased natural habitat within one-third mile  tended to have higher parasitoid populations, more parasitism and lower pest numbers. Cover crops support many native bees and especially spiders - they have been found to comprise 90% of the arthropods in some vineyards! Stacking multiple diversification practices in the vineyard yields many positive results.

Encouraging Bats as Pest Control Agents – Elissa Olimpi described how bats help provide economically important pest control in many crop systems including wine grapes, and are valued at $3.7 billion/year in North America. She shared how diversity in and around the crop increases bat activity. Having a greater number of crops and smaller fields can increase bat presence. Bats also like to fly along treelines and hedgerows. Increasing habitat on these field edges can boost bats’ activity and pest control services. 

Managing Wine Grapes with Sap Analysis – Jenny Garley (New Age Laboratories and Agronomical Services) discussed how sap analysis can help to track macro- and micro-nutrient levels at different growth stages as management strategies are tried in the vineyard. Paicines Ranch is using sap analysis to measure the influence of sheep on these levels.

Holding Birds
Austin Spence (left) and WFA's Jen Paludi (right) gently hold birds during mist net demonstration.

Demonstrating Avian Research – Early morning risers got to participate in a mist-netting demonstration led by Austin Spence (UC Davis) and Elissa Olimpi (Virginia Tech). Birds captured in the mist net are removed quickly and placed in small cloth bags where they often leave feces that can be assayed for both the bird’s diet and the presence of pathogens. A Western Bluebird, a House Wren, and an Anna’s Hummingbird were viewed up close.

The Day Before For those who came to enjoy a stay at the ranch, co-owner Sally Calhoun led a walking tour the day before showcasing the returning biodiversity as sheep grazing using high stocking rates for short periods is transforming the 7,600-acre ranch. The tour was followed by yoga, dinner and an evening bird walk with night vision binoculars, which revealed several owls and bats on their initial hunting rounds.