Natural Product Helps Prevent Cherry Cracking

Cherry cracking can be devastating to a grower. One day before harvest, everything looks beautiful. Then, it rains, and an entire crop can be ruined.

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“I have seen where growers have gone the day before they were planning to pick and it would rain. Their crop was totally destroyed or at least partially destroyed,” says Lynn Long, Oregon State University (OSU) Extension educator.

Over the years growers and researchers have tried to tackle the problem of cherry cracking in many ways. Covering cherries is a popular way to combat rain cracking abroad, however it is an expensive venture to cover entire orchards.

“Growers in the Pacific Northwest don’t make enough money per pound to be able to afford to cover their cherries with plastic,” Long says.

Expands With The Fruit
A new product developed by researchers at Oregon State University hopes to prevent and lessen the risk of cherry cracking.

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SureSeal is an elastic, water-repelling biofilm that is a cuticle supplement. It contains only food-based products and expands as the fruit grows. This product was developed by Clive Kaiser, an OSU horticulturist and Extension tree fruit expert and J. Mark Christensen, an OSU pharmacist. Kaiser had experience working on biofilm overseas and Christensen had patented biofilm for pharmaceuticals.

“In formulating the novel hydrophobic biofilm we eliminated any ingredients from prior technologies that would not be considered organic by FDA and the National Organic Program and came up with a novel elastic hydrophobic biofilm that stretches with fruit growth,” Kaiser says.

Kaiser says SureSeal is diluted in water, 1 gallon of product to 100 gallons in a tank and applied on the trees with a mist blower.
“The water expresses from the emulsion and a hydrophobic biofilm approximately 13 micrometers thick is left behind to protect the fruit against the damaging effects of water droplets,” he says.

In The Field Testing
Long has been evaluating SureSeal for eight years. He likes the product because growers need less applications than with a carnauba wax.

“We have in my trials applied it only once, from green to yellow — straw color, when the cherries are changing from green to yellow, and had some really good protection,” Long says. “The manufacturer recommends two applications, one at straw color and another 10 days later.”

Long points out SureSeal does not protect against long, sustained rains where cherry cracking comes from an excess of internal water uptake through the roots. What SureSeal does protect against is water brought in through the surface of the fruit.

“When heavy rainfall (greater than 1.5 inches) occurs, up to 60% cracking can be observed in the field when fruit are not protected. Light rainfall (up to 1.5 inches) can result in between 5% and 25% cracking,” Kaiser says. “When commercial farmers in the Pacific Northwest have more than 25% cracking, it is not worth picking the crop. Prevention of cherry cracking can mean the difference between harvesting a crop or not.”

During Long’s evaluations, SureSeal has been proven to be effective in reducing fruit cracking by up to 50% or more.

“If you’re at 25% cracking and you’re right on the line and you had applied Parka+ to one of your blocks and not to the other, if you’ve got 25% cracking in one block and 12% cracking in the other block, the economics are pretty good in that type of situation because you can still pick that block at 12% cracking where you may not be able to pick it at 25% cracked,” he says.

More Protection
OSU has licensed the SureSeal technology to Cultiva LLC, who manufactures the SureSeal-based products and markets them under different trade names including Parka, for cherries, BluGard for blueberries, and Pomcho for apples.

In Long’s evaluations he noticed that cherries treated with SureSeal had improved fruit quality and were higher in sugar. After evaluations of different formulas, it was discovered that stearic acid, the base for the initial formulations, contributed to those improved qualities.

“That’s the difference between Parka — which has been sold the last two years — and Parka+. The first two years it was a pome oil base and now it’s back to a stearic acid base where we were seeing some of those fruit quality improvement characteristics,” he says.

Although the term biofilm sounds confusing, Long wants to make it clear that the product is safe.

It’s not a pesticide, it’s not a fertilizer, it’s nothing like that. “It is all food-grade material that is being applied,” he says. “It gives the growers a little bit more protection that they wouldn’t have otherwise.”

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