Organic Farm System: Woodleaf Farm

Organic Agriculture September 12, 2016 Print Friendly and PDF

eOrganic authors:

Carl Rosato, Woodleaf Farm

Helen Atthowe, Woodleaf Farm

Alex Stone, Oregon State University

Organic Farm System: Woodleaf Farm

Woodleaf Farm

System Overview

About Woodleaf Farm

Farmers: Carl Rosato and Helen Atthowe

Location: Oroville, in the Sierra foothills of northern California (Fig. 1: Area Map)

Crops: Peaches (4.5 acres), pears (1.5 acres), apples (1 acre), cherries (0.5 acre), plums and pluots (0.25 acre), vegetables and kiwis (0.5 acre)

Woodleaf Farm is known in northern California for its large, unblemished, juicy, and flavorful organic peaches (CUESA). In 2013, the marketable peach crop was 79% premium grade. In 2014, 86% and in 2015, 81% of fruit was sold as premium fruit.

Markets: Regional farmers markets (7 per week) and 10% wholesale to restaurants

Years in organic management: 1982 (certified by CCOF) to present

Total farm acreage: 26 acres

Cropped acreage: 8 acres

Landscape design: Seven 1- to 1.5-acre fields with native oak/pine forest on 90% of field margins (Fig. 2: Farm Fields & Soils Map)

Regional agricultural production: Butte County is a significant producer of tree fruits and nuts. Its 2010 gross agricultural production exceeded $620 million, including $9.7 million from peach production.

Climate and soils: Mediterranean (wet winters, temperatures to 20°F; dry summers, temperatures to 100°F). Annual precipitation is 35 inches. Soils are classified as capability class VII by the USDA Natural Resources Conservation Service and rated as "poor" for agricultural use (Fig. 2: Farm fields & soils map)

Awards: EcoFarm Steward of Sustainable Agriculture Award, 2012.

Farm Philosophy

Woodleaf Farm's focus is on supporting ecological relationships rather than on managing specific crops, problems, or pests. Carl believes that "leaving the soil as undisturbed as possible, annual additions of different kinds of high-carbon organic materials, and soil mineral balancing grows a healthy tree and keeps insect and disease problems in check."

Carl also focuses on habitat-building, saying,"Native forest on field margins and letting the perennial living mulch go to flower brings beneficial biological control organisms into crop fields and has been helpful in keeping insect damage in check over time."

Key Farm Design and Soil and Habitat Building Strategies

  • Small crop fields bordered on at least three sides by native oak/pine forest
  • No-till/reduced tillage
  • Diverse high-carbon/low-nitrogen organic soil amendments linking nutrient mineralization to soil organic matter decomposition
  • Soil mineral balancing
  • Perennial living mulch to keep soil covered year-round and provide winter shelter and season-long bloom for natural enemies
  • Disease-resistant varieties and in-field cultivar mixtures (Disease Table 2)
  • Field sanitation and regular pruning
  • Mineral mix foliar sprays at bloom
  • Gravity-flow microsprinkler irrigation to avoid fruit and foliage wetting
  • Cats for gopher control

Soil Management System: Build Soil to Promote Balanced Tree Growth and Flavorful, Mineral-Rich Fruit

Woodleaf's goals are to optimize soil organic matter, link soil organic matter decomposition to nutrient mineralization, support a diverse soil microbial community, and balance soil minerals. The soil management system (Soil Table 1) includes:

Soil health indicators generally show positive trends (Soil Table 2). Between 1982 and 2014, average soil organic matter increased from 2.2% to 5.1%. The high carbon/low nitrogen nutrient cycling/recycling system results in 10 to 20 inches of annual tree growth; good yields of high-quality, flavorful fruit; high levels of soil organic nitrogen; relatively low levels of soil nitrate-nitrogen; and peach leaf nitrogen in the adequate range.

Macronutrients have increased and are generally balanced at target levels, but some micronutrients (particularly boron) have not increased and are below targets.

Read more about the soil management system at Woodleaf Farm here.

Insect Pest Management System: Maximize Ecological Function and Minimize Off-Farm Inputs

Woodleaf's goal is to build and manage habitat for biological control organisms (e.g., insect predators and parasites, birds, bats, soil and foliar microorganisms). Pests are sprayed only when absolutely necessary. The insect pest management system includes both farm-wide practices (Insect Table 1) and pest-specific strategies (Insect Table 2).

  • Landscape-level diversity, provided by small crop fields bordered on at least three sides by native oak/pine forest
  • No-till/reduced tillage
  • Perennial living mulch groundcover beneath trees and in row middles to provide in-field/interspersed plant diversity, season-long pollen/nectar/seed food sources, and winter cover
  • Selective mowing of the perennial living mulch to avoid disturbance of natural enemies at key pest pressure times
  • Low nitrogen fertilizer inputs to maintain balanced tree growth, thus suppressing insect pests
  • Sprays only when necessary (Insect Table 2): No sprays on peaches in 2014 and 2015; in the past, Woodleaf sprayed Spinosad (Entrust®) on peaches for thrips. Currently, cherries are sprayed with Spinosad (Entrust®) for spotted wing drosophila.

Fruit yield and quality losses to insects have mostly decreased over 30 years, according to Carl. This observation is supported by reduced insecticide use (Insect Fig. 1). Records document less than 10% average fruit damage (Insect Table 3 and Insect Table 4) and high predator/parasite populations (Insect Figs. 2A and 2B,  and Figs. 3A and 3B).

Spotted wing drosophila (SWD) remains a challenge at Woodleaf and is not suppressed by the insect pest management system. When unsprayed in 2014, 30% of cherries were damaged by SWD.

Read more about the insect management system at Woodleaf Farm here.

Disease Management System: Create Conditions Unfavorable to Pathogen Growth

Woodleaf's goal is to prevent disease infection by managing for balanced tree growth and healthy soil, while utilizing good cultural practices. The disease management system includes both farm-wide practices (Disease Table 1) and disease-specific strategies (Disease Table 4).

  • Disease-resistant varieties and in-field cultivar mixtures (Disease Table 2)
  • High-carbon/low-nitrogen organic soil amendments to maintain balanced tree growth
  • Soil mineral balancing
  • Foliar mineral sprays at bloom to enhance tree/fruit health (including 6–10 lb/A sulfur)
  • Selective mowing of the understory to maximize air flow and reduce disease infection
  • Good cultural practice, including careful attention to field sanitation
  • Regular pruning to maintain an open tree shape (twice per year)
  • Microsprinkler irrigation to avoid foliar and fruit wetting
  • Minimal sprays: Besides sulfur-containing mineral mix sprays, the only spray currently used is lime sulfur for peach leaf curl (Disease Table 4).

Fruit yield and quality losses to diseases have declined over time, especially losses to peach brown rot and apple scab, according to Carl. This observation is supported by crop yield and quality monitoring records (2013–2015). Pear fireblight, peach brown rot, and peach leaf curl remain management challenges. Fireblight and peach leaf curl do not appear to be suppressed by Woodleaf's farm design and soil/habitat-building practices. Brown rot may be suppressed, however, since it now occurs at a relatively low level.

Read more about the disease management system at Woodleaf Farm here

This article is part of the Woodleaf Farm Organic Systems Description.

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This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.