Organic Apple Production In High Tunnels

View the project final report

Commodities

• Fruits: apples

Practices

• Crop Production: high tunnels or hoop houses, varieties and cultivars
• Farm Business Management: budgets/cost and returns
• Pest Management: cultural control
• Production Systems: organic agriculture
• Sustainable Communities: local and regional food systems, new business opportunities

Locally produced organic apples are in demand, but most organic apples are produced in desert areas of Washington, where the dry climate reduces infection from fungal diseases such as apple scab.  In the north central U.S., wetter weather favors disease, and most organic apple growers grow disease-resistant varieties and/or spray organic fungicides such as sulfur.  Disease-resistant varieties can be difficult to market if they are not the most flavorful varieties or if they are not familiar to consumers.   Organic fungicide sprays are expensive, require frequent re-application, and can have negative effects on apple trees, beneficial insects, and the environment.  Trees grown in polyethylene-covered tunnels are protected from rain and should therefore suffer less disease.  In this project we evaluated the growth, yield, and profitability of seven apple varieties grown organically in unheated polyethylene-covered high tunnels.  We raised trellised, dwarf trees using the tall spindle training method.

We planted our high tunnel trees in spring 2019 and have raised them for three growing seasons, with harvests in 2020 and 2021.  Key observations and conclusions from our project are:

• Trees grew vigorously and filled the available space quickly.  With timely branching training and notching of the leader, trees developed a good structure and have not outgrown their space.
• Covering tunnels with opaque silage tarp in winter was an effective way to prevent winter damage from rapidly fluctuating temperatures.
• Virtually no diseases other then powdery mildew were observed in the tunnels.
• Insect damage to foliage and fruit in the tunnels was common and overall at a similar level to what we normally see in outdoor trees.
• Flowers in the tunnel suffered significant frost damage in 2020 during a bloomtime freeze event.
• Fruit of many varieties suffered significant heat-related defects in the tunnels.
• Average yields were 7 lbs/tree in 2020 and 25 lbs/tree in 2021 (about 200 lbs per acre and 750 lbs per acre, respectively)
• Varieties differed enormously in yield and susceptibility of their fruit to heat damage.
• Although myriad factors affect profitability, we estimate that on our farm it would take 10+ years to recoup the costs of constructing tunnels and planting apple trees in them.

We have shared project results through a field day, conference poster session, a published report on our website, emails, and press releases.  Four periodicals aimed at farmers have agreed to publish a summary of our project in 2022.

1. Measure costs, yields, and profitability of organic apples raised in high tunnels.
2. Compare yields and profitability of seven apple varieties in high tunnels.
3. Measure incidence of common apple diseases and insect pests in high tunnels.
4. Share results with other growers through our website, a field day, emails to grower list-serves, articles in grower publications, and a conference poster session.