RESEARCHERS ANALYZE A NEW PRODUCT TO IMPROVE FRUIT QUALITY 

By Amanda Vance, Faculty Research Assistant, OSU  

In 2017, the berry crops research team from Oregon State University, led by Dr. Bernadine Strik, received a grant from the Clackamas County Innovative Fund Program to investigate a new product called Parka™. This product is a food-grade crop cuticle supplement aimed at reducing splitting. It has worked for rabbiteye blueberries in the southeastern U.S. and there was some anecdotal evidence that it may also increase berry firmness. It has been widely adopted by the cherry industry over the past several years for its effectiveness at reducing splitting and improving post-harvest shelf life. We worked with the manufacturer, Cultiva, as well as a grower-collaborator, to develop two trials to test Parka™ in northern highbush blueberry in the Willamette Valley.

Trial 1 was conducted in a mature “Elliott” field at the North Willamette Research and Extension Center. There were three treatments each consisting of three applications of 2 quarts/acre in 50 gal water/acre via airblast sprayer: 1) label instructions (5–10mm berry size, 10–20 percent color change, between 1st and 2nd harvests); 2) “early” (5–10mm berry size, 10–20 percent color change, and 7–10 days pre-harvest); and 3) “late” (10–20 percent color change, 7–10 days pre-harvest, between 1st and 2nd harvests). A water sprayed control was used for comparison.

Trial 2 was conducted in a mature “Legacy” field at a grower-collaborator site. This trial was aimed at determining if Parka™ could effectively be applied via a mist or sprinkler system (chemigation) to reduce the knockdown of fruit that may occur when driving a tractor down plant rows during fruiting. The same rate was applied as in Trial 1 (2 quarts/acre), and these were compared to an untreated control.

Fruit samples were harvested by hand just prior to each commercial harvest (three machine harvests of “Elliott” and five hand harvests of “Legacy”) and analyzed on the day of harvest for berry weight, firmness, diameter, skin toughness, Brix, splitting (occurred in “Legacy” only) and appearance. Additional samples were analyzed after two and four weeks in cold storage for the same traits, as well as percent moisture loss during storage. Total harvested yield was also measured in “Elliott” and a cumulative yield from the three harvests calculated.

In both cultivars, there was no consistent impact of Parka™ on any measured trait (yield and all of the fruit quality parameters mentioned above from each of three harvests in “Elliott” and five in “Legacy”) at the rates, timings and methods applied. While we did have significant differences for some traits on some harvests or storage dates, there were no clear trends across the season. This means that at times a particular treatment may have had the firmest fruit or the toughest skin, whereas on other dates the water-sprayed control was better. All measurements were within what would be considered a normal range for these blueberry cultivars and plots contained healthy, vigorous plants.

Splitting can be an issue in some highbush blueberry cultivars so it was unfortunate that we did not see any benefit of applying Parka™ for improving fruit quality, shelf life or reducing splitting in these cultivars. It is possible that other rates or formulations of this product might be of benefit.

If you have questions or would like more detail on our methods or specific results, please contact Amanda Vance (Amanda.vance@oregonstate.edu).