Evaluation of Novel Wild Apple Hard Cider Cultivars for the Northeast

Commodities

• Fruits: apples

Practices

• Crop Production: plant breeding and genetics, varieties and cultivars
• Pest Management: genetic resistance

The focus of this project is to increase key horticultural knowledge for ten high-quality novel wild cider apple cultivars newly available for planting in the Northeastern US, in order to promote these varieties for use in commercial cider orchards. Wild apple gene pools represent a useful and underutilized source of pest and disease resistance. Ten elite wild apple varieties have been identified from hundreds of unique crowd-sourced submissions through a rigorous selection process at the annual Wild Apple and Seedling Pomological Exhibition. Varieties will be evaluated for characteristics including vigor, tree form, pest and disease resistance, bloom time and harvest phenology.

Through tracking horticultural characteristics over three growing seasons, the major study objective is to identify the most robust and productive varieties and to screen out any varieties which have shortcomings, such as weak growth, unusual bloom period, or susceptibility to pests and/or diseases. Allied to that goal is the gathering of data on bloom and harvest periods, in order to aid orchardists in the planning of orchard blocks.

The varietal evaluation will take place in a randomized block design orchard grown in a vertical axis single-wire trellis system. Data will be gathered for three seasons and then statistically analyzed for significant differences. The data gathered during this period will be tabulated for each variety and presented in report form for interested apple growers. Grower outreach will be accomplished through use of social media, traditional media, and an on-site orchard tour at the culmination of the third year in 2029.

Our overall objective is to assess the viability of wild-sourced hard cider apple varieties grown in a commercial orchard setting by screening for characteristics and data useful to growers; and at the completion of the project, to promote the planting of the best-performing varieties to other orchardists and growers in the region. This research project is broadly modeled after the Canadian study of hard cider apples cited in the introduction (Plotkowski and Cline 2021), but will be more circumscribed in scope.

Viability of variety will be assessed by monitoring tree health. Tree health will be quantified by monitoring incidence of apple scab, fireblight strike, and foliar feeding by pests. Apple scab, Venturia inequalis, is a common and potentially disfiguring fungal pathogen which affects foliar health and fruit development and appearance. Fireblight, Erwinia amylovera, is an increasingly common and potentially devastating bacterial pathogen which has the potential to kill flowers, branches, and even entire apple trees. Foliar feeding by various insects is a common seasonal fruit tree injury. Insect pests have demonstrated preferences for feeding on specific cultivars. New wild apple varieties will be compared to each other and also to a standard control, in this case cv. 'Enterprise'. We have selected Enterprise as a representative sample of a modern disease resistant apple that is well-researched and displays vigor, productivity, and some disease resistance; it will be a useful yardstick by which to measure experimental varieties.

Horticultural data of interest to commercial growers related to tree phenology (flowering period, harvest period), tree form, and vigor will also be recorded. Bloom time is important to track because apple trees rely on cross-pollination in order to produce viable fruit. Bloom time may be staggered by several weeks across apple cultivars, so it is important to include cultivars with overlapping bloom periods when planning orchard blocks. Harvest data is important for orchard planning. Growers must know exactly when fruits will ripen, and in which order. Ideally, bearing time will be distributed across harvest season in order to avoid a glut of ripening fruit. Tree form is helpful to know when pruning, in order to avoid removal of fruit buds, and to encourage the desired type of pruning response. Cultivar vigor is equally important, as it will influence final tree size, spacing in row, and approach to pruning.

Specific project objectives for each new apple variety are as follows:

1. Assess and record apple scab susceptibility.
2. Assess and record fireblight susceptibility.
3. Assess and record foliar pest activity.
4. Record variety bloom period.
5. Measure and record variety vigor and determine tree growth form.
6. Record variety harvest period.

We have consulted with both our technical advisor Elizabeth Garofalo and additionally Dr. Wesley Autio, UMass Fruit Science Professor Emeritus (and biostatistics specialist), to refine the experimental block design to evaluate a precise number of cultivars with enough replications for statistical validity.