Oct 7, 2020

Calcium eases the Honeycrisp headache

{Sponsored} “I just love seeing fruit in the box at harvest,” says Jill Tonne, a Simplot Grower Solutions orchard consultant in Ephrata, Washington. “2020 has been a hard year in so many ways but despite all that, the predictions are good and the market is looking stronger.”

Indeed, when the Washington State Tree Fruit Association (WSTFA) released its forecast for the 2020 apple crop, growers heaved a collective sigh of relief in knowing that strong consumer demand would be met with an ample and high-quality harvest—134 million standard 40-pound boxes, almost identical to 2019’s 133.9 million box crop.

“Growers haven’t had an easy year,” notes Jill, who’s been providing advice and consultation to Washington’s apple growers for more than 15 years. “Budgets are top of mind and that’s required a rethink of programs and approaches.”

Washington’s orchards produce six in every ten apples consumed in the United States. Gala will account for around a quarter of this year’s crop, ahead of Red Delicious and Fuji. But it’s the runaway demand for Honeycrisp that creates headaches for Jill’s clients.

Spectacularly popular amongst consumers, the Honeycrisp isn’t viewed with the same enthusiasm by those who grow it. The fabulous crunch—and mouth-filling flavor—that draws consumers into paying premium prices for the apple is its sole redeeming feature, for it’s not a variety that can be described as ‘easycare’.

“It’s technically needy,” explains Jill, “and a variety that typically presents the most agronomic difficulty for the grower in managing energy, nutrients and physical attributes.

“Yes, it can be highly profitable. But only through extreme attention to detail and careful management of inputs. Growers have to be on top of their game to produce a consistent crop that delivers high pack-out rates in the bin.”

Typical Honeycrisp issues are its brittle wood, which can result in snapped and broken branches, and a propensity to crop too early. It’s also vigorous, requiring more training and pruning than other varieties—not a helpful trait in a year where labor shortages are top of growers’ minds.

“But for the fruit itself, one of its biggest shortcomings is its susceptibility to bitter pit,” notes Jill. “Although by no means the only variety to suffer this physiological condition—caused by a lack of calcium in the developing fruit—Honeycrisp’s tendency to grow big can exacerbate it.”

Growers are often dealt a double blow in trying to avert bitter pit: foliar applications of calcium chloride, the default preventative treatment, often provide inconsistent results. “It’s inexpensive, so that defrays some of that frustration, but not so the detrimental effects it can have on fruit finish, particularly lenticels,” points out Jill.

“Sometimes it’s ‘hot’ on the tree too – growers often see some leaf margin burn.”

Problems with calcium uptake aren’t new. Plant nutritionists have long known that calcium is a ‘problem’ nutrient. Plants not only lack the ability to store calcium, but also any ability to mobilize it and move it around. What’s more, calcium is absorbed only when auxin, an important plant hormone involved in cell division, is present in sufficient quantity. It’s often this last point that causes problems in resolving bitter pit.

Auxin is involved in cell division, thus new cells and tissues, i.e. growing fruit, have high levels. As a fruit matures, cell activity switches to expansion and auxin levels drop – as does its ability to absorb calcium. It’s easy to see how large Honeycrisp apples can be extra-vulnerable.

It’s why Jill’s issued a lot of recommendations this year for a new product that effectively ‘forces’ calcium into plant cells. Cell Power® Calcium Gold, from California-based nutrition specialists OMEX® USA, contains a formulation known as ‘LoCal’. It’s a specially developed ‘calcium transport stimulant’ that mimics the effect of auxin, achieving the hitherto impossible: calcium uptake and transport in the absence of auxin.

“It’s rare to have this kind of new technology in a nutritional product,” enthuses Jill, “so it’s received an enthusiastic welcome from growers. By helping the plant to absorb calcium where it’s really needed, using a process that already exists within the plant, we also have a product that’s soft on the fruit and without any of the drawbacks associated with standard foliar calcium treatments.

“Calcium Gold is a straight substitution for foliar calcium, with applications every 5-7 days post-flowering. So, it’s an easy switch to make. Growers are reporting better fruit finish, improved quality and longer storage life, including firmer fruits for longer. Given calcium’s importance in cell wall structure, that all makes sense.

“We’ve not yet done full side-by-side comparisons but those blocks where we’ve applied Calcium Gold have shown a noticeable difference, with better and higher calcium ratios confirmed through sap analysis and fruit samples.

“Growers also tell me they’re getting higher pack-outs, which should translate into improved margins.”

Learn more at www.omexusa.com.

The product names and brands referenced here are registered and trademarks of OMEX® Agrifluids, Inc. © OMEX® Agrifluids, Inc. 2020.