Issue link: https://read.dmtmag.com/i/769560
26 JANUARY 15, 2017 Good Fruit Grower www.goodfruit.com were commonly used at the time. Fast-forward 30 to 40 years and the world now craves such softer approaches to disease control, including fungi. "There has been a growing interest in using natural fungal biocontrol agents supported by consumers. Fruit packers are much more willing and accepting natural alternatives to synthetic fungicides," said Richard Kim, director of plant pathology for Pace International. The tree fruit industry currently uses synthetic chemicals pyrimethanil, fludioxonil, thiabendazole and difenoconazole for various rot diseases by drenching in a dump tank, fogging in cold storage, waxing on the packing line or spraying on the packing line, said Mike Willett, manager of the Washington Tree Fruit Research Commission. Resistance development is a concern for all of them. That's why biorational, or nontoxic, substances such as natamycin may provide another valuable option for disease control. "That's good to have more tools in the mix," Willett said. No resistance Natamycin may lead to no resistance at all, ever, Kim said. In a 2009 report, the European Food Safety Authority concluded "there was no concern for the induction of antimicrobial resistance." The organization provides scientific advice to European nations. Natamycin has a different mode of action than the synthetic chemicals currently used to control blue mold and gray mold in pome fruits; brown rot, gray rot and Rhizopus rot in stone fruits; and green mold and sour rot in citrus fruits. It interrupts the formation of cell membranes, a fundamental part of any organism's reproduction. Fungi can't circumvent that. In contrast, synthetic chemicals block certain growth pathways and the fungi usually find a way around it to grow and survive over time. Kim's tests at the Pace laboratory showed natamycin to be just as effective as fludioxonil on gray mold and blue mold on apples, he said at the Pace postharvest Hannah Webb inoculates Bing cherries with Botrytis cinerea fungus spores along with Jae Kwak, left, and Richard Kim, right, during natamycin trials in mid-June, 2016. Over four years ago, Kim and colleagues began conducting trials that found the fungicide helps prevent postharvest fungi in pome, stone, cherries and citrus fruits.