cider apples at the 2021 GLEXPO

Jan 10, 2022
Unruly cider apples can be tamed

Apples prized by cider makers for their high levels of tannins and acids are difficult to grow, with tendencies to biennial growing and other undesirable growing characteristics.

A new set of studies from Cornell University looks at different thinning practices – studying what is being pursued by growers, and which techniques seem to work best in trials.

Graduate student David Zakalik, who conducted the research for his master’s degree project under the supervision of professor Gregory Peck, presented his findings in a December presentation at the Great Lakes Fruit, Vegetable and Farm Market EXPO in Grand Rapids, Michigan.

Counting the costs

Part of Zakalik’s presentation was a microbudget he developed for growing cider apples based on discussions with growers and Extension staff. He assumed that the apples would be sold at the farm for about 35 cents per pound. Planting density taken to be 900 trees per acre, the same as the farm where he did his fieldwork. Harvest costs varied from $18 to $36 per bin – some growers he talked to pay pickers a higher rate for the smaller cider apples.

“If you have just way more, by number, fruit to pick, it takes longer to fill up the same 900-pound bin,” he said. “That’s the sort of compensation people are doing.”

Chemical thinning costs were estimated by another researcher as $170.52 per acre per year, while Zakalik estimated hand thinning costs were at $675 per acre per year, based on a rate of 45 work hours per acre and New York’s adverse effect wage rate of $15 per hour.

David Zakalik
Cornell University’s David Zakalik speaks at the Great Lakes Fruit, Vegetable and Farm Market EXPO in Grand Rapids, Michigan. Photos: Stephen Kloosterman

Zakalik’s budget analysis found a profitability for the Dabinett apple variety with three years of chemical or hand thinning. Other apple varieties have been slower to reach net profitability, but Zakalik said chemical thinning would have a projected net increase in profitability for all seven cider cultivars he’s studying in year four. Five of the seven – Binet Rouge, Brown Snout, Dabinett, Harry Masters Jersey and Michelin – responded well to hand-thinning, having a projected net increase in profitability by year four. Two varieties projected to be unprofitable to hand-thin, regardless of crop load, are Chisel Jersey and Geneva Tremlett’s Bitter. In the study, nine fruit per cm2 of trunk cross-sectional area (TCSA) was the most profitable crop load studied, and six fruit per cm2 TCSA was only profitable for Dabinett.

Zakalik noted several limitations to the microbudget – one being the relevance of farm gate prices. Most high-tannin fruit goes into the growers’ own cider products.

“An important limitation of our work is that we were looking at a high-density ‘tall-spindle’ system with a dwarf rootstock, but many growers are planting their trees in a lower-density planting with more vigorous rootstocks, he added. “So we don’t know how our results will translate to a different system.”

Recognizing that most of the specialty apple varieties are grown for their tannins, aka polyphenols, used during the cider making process, Zakalik also studied how thinning adjusted the cumulative “tannin yield” of the trees.

In four years of being thinned to nine fruit per cm2 TCSA, all the thinned trees are projected to produce more total tannin content and yield weight. But reaching that point took time – in the first three years, only two of the seven varieties – Dabinett and Harry Masters Jersey – showed an increased yield in tannins.

Apple trees that bear only biennially will reduce the long-term cumulative yields of the apples. Apple trees that bear too much fruit in one season, will negatively impact the quality of the juice.

Zakalik noted that the number of apples per tree doesn’t necessarily equate to the amount of tannins produced, so it’s important not to over- or under-thin.

“The industry really needs an annual-bearing Tannin bomb cultivar, that is annual bearing, it’s rich in tannins so you don’t need a lot of acreage to get a lot of tannin,” Zakalik said. Late- blooming English and French varieties can be susceptible to fire blight.

Survey says…

Zakalik’s work included a 2021 survey of nearly 200 commercial cideries, 90% of whom were small-to-medium size, and about 75% of whom did have a taproom or a tasting room. Sixty-eight percent of the respondents did have bitter apple varieties, and 17% did plan to have them in the future. The leading reason the growers had for not using bitter varieties was the availability.

While most non-growers said biennial-bearing varieties wasn’t bothering them, 84% of growers said it was. Among the growers in the survey, 46% were not doing any thinning. Growers had very few large plantings, however, many of the growers were growing between 11-20 different cider varieties, experimenting to find what worked best.

“Your variety selection is really important, and hopefully this hard data that we’ve found will be helpful to growers to make an informed decision about what variety they want to take a chance on, or expand their planting of,” Zakalik said. “If you’re going to try thinning, you need to think over the long term, multiple years. But then, sometimes thinning isn’t worthwhile, either, because a variety’s too biennial or because it’s an off year. But thinning can reduce your biennial-ism, and it can improve your yields over four years in certain cases. And thinning will improve juice quality, particularly tannin content, overall.”

“Inconsistent yield, inconsistent supply, is a real challenge. If you’re going to try to sell these varieties, you want to have a sort of established relationship. Make sure that you know you’re going to be able to supply some fruit to your buyer.”

Sharing a resource

Also at the Great Lakes Fruit, Vegetable and Farm Market EXPO, Brighid O’Keane of the Cider Institute of North America spoke briefly about the group’s work to create resources for professional cider makers.

The institute, formed in 2016 with board members from around the U.S., has developed courses for education. Roughly 300 individuals have completed a “Foundation Certificate” program for cider and perry production. A more advanced certification program is also being developed.

The institute has developed an easy-to-use reference tool, a wheel that allows cider makers to look up 15 of the most common flaws in cider. It also established a website,, that lists equipment for sale as well as jobs in the industry, and developed a handbook.

Future plans include an introduction to cider making class, skills-based advanced resources, resources on cider economics and a cider-specific lab manual.

— Stephen Kloosterman, associate editor; Photo at top: Bittersharp apples such as Geneva Tremlett are prized by cider makers for their acidity and tannins.

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