Cherry cracking reduced using commercial biofilm

Rain and humidity are the curse of the cherry crop, bringing cracking to the fruit rendering it too ugly to market fresh. But other culprits may cause the headache as well, says Clive Kaiser, Oregon State University horticulturist.

“Rootstocks may also be susceptible,” he told the Oregon Horticultural Society at its annual meeting in Portland, Ore., in January. “And the chemical properties of the cuticle can also be a cause of cracking.”

Key Points

Biofilms appear to protect cherries well from cracking.

The commercial product, SureSeal, is already available.

Oregon State University holds the patent on the product.

Whatever the villain may be, a hero helper may be on the way in the form of a biofilm covering for the crop that disperses water. Already patented by OSU and marketed commercially as SureSeal Biofilm, research continues between the university and private industry to further develop the protectant. In some tests, only one out of 10 cherries cracked, he reported.

Trials in several cherry production areas show promise for the product, said Kaiser. But there were more promising features, he added, including added firmness to the fruit and in some cases even larger cherries resulted from using the material. Sugars were also up in treated crops.

As a result of the Washington Tree Fruit Research Commission-funded studies, researchers conclude that the product can be used as a treatment against sweet cherry cracking, with further studies necessary. To date, the product has not been tested on brine cherries.

About 600,000 gallons of the commercial product were released last year, said Kaiser, and the SureSeal treatment is now available to growers. Kaiser is currently writing a report on the studies.

Recommendations for control of cherry cracking urge growers to select crack resistant varieties such as Regina, Attika and Lapins, using care to manage the soil moisture carefully. Keeping orchard humidity down is also important to management.

Other areas of the world protect cherry trees from rain by using tents to cover the crop, a practice not widely adopted by Pacific Northwest producers. In Norway, said Kaiser, fruit cracking was reduced from 24.6% to 9.8% when trees were treated were with SureSeal in combination with plastic ground covers.

“All except one of these studies found that use of SureSeal resulted in significantly higher total soluble solids and increased stem pull force than untreated control fruit,” he said.“Due to high labor costs in the Pacific Northwest, when rain-induced fruit cracking in sweet cherries exceeds 25%, fruit are not picked,” says Kaiser.

The use of the “novel, elastic, organic biofilm, SureSeal, which significantly reduces fruit cracking in sweet cherries,” can help.SureSeal is a hydrophobic copolymer of stearic acid, cellulose and calcium.

Tests are showing that an application of 1% Sureseal applied at straw color and again 10 days later “consistently reduced fruit cracking when compared with untreated control fruit,” Kaiser said.

This article published in the March, 2011 edition of WESTERN FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2011.