New postharvest decay control treatments that are exempt from residue tolerances in the United States

New postharvest treatments need to be continuously developed in the U.S. to meet demands for: export residue tolerances, consumer safety concerns, for decays poorly managed, and to counter pathogen resistance to registered compounds. Exempt-from-tolerance and biopesticide compounds benefit from accelerated registration due to their favorable safety characteristics. Several of these were either recently registered (potassium phosphite, K-PO3), are currently in the registration process (polyoxin-D), or are evaluated for their potential in decay control (EXP-13). Citrus brown rot originates from field infections by Phytophthora species and can cause significant losses. Phosphonates are registered pre-harvest treatments. Because no effective postharvest treatments were available for its management, K-PO3was evaluated. At 1000-4000 mg/L, K-PO3 was similarly effective as azoxystrobin, mandipropamid, or fluopicolide in protecting fruit from brown rot when applied before inoculation. Only K-PO3, however, had post-infection activity, reducing decay to low levels in treatments done 20-24 h after inoculation. K-PO3 is now registered for postharvest use with exempt status. International tolerances are pursued for major export markets. Polyoxin-D, a fermentation product of Streptomyces cacaoi var. asoensis, has a U.S. biopesticide registration for field use on various crops. We found it most effective against gray mold (Botrytis cinerea). At 50-200 mg/L, it was similarly effective to conventional postharvest fungicides on stone fruits. On pome fruits and pomegranate, its efficacy was more variable and depended on fruit cultivar and treatment time after inoculation. Polyoxin-D is scheduled for postharvest registration in 2015. Currently, we are evaluating EXP-13 for control of Penicillium decays of citrus and pome fruits. Although moderately effective by itself, high control was achieved when mixed with low concentrations of registered fungicides. Our investigations indicate that exempt-from-residue and biopesticide compounds can be valuable postharvest treatments and potentially, may be approved for organic production. They can also be mixture partners with other fungicides in an effort to minimize resistance development. SourcesNew postharvest decay control treatments that are exempt from residue tolerances in the United StatesJ. E. Adaskaveg, H. Forster, V Postharvest UnlimitedDepartment of Plant Pathology and Microbiology, University of California, Riverside, CA, USA, jim.adaskaveg@ucr.edu V Postharvest Unlimited, ISHS International Conference, 10-13 June 2014, Cyprus, http://web.cut.ac.cy/postharvest/ Picture by 184.107.87.82, info rural ? Key words Poscosecha????? postcosecha???? postharvest?????? na-oes? ???????????? ?????????????????? post-r?colte?????? ?????????????????????????????????????? na-oogst?????????? post-raccolta???? Obr?bka po?????? p?s-colheita????? ?????????????????????? hasat sonras???? ??????????? Ernte??? ??????????????????????? ????????????????????? postcollita???????? poskliz?ov頠??? ?????? ??????????????? nakon branja?? pozberov頠????????????????? obdelovanje zemlje po?? post-colleita????? ??????????????? pascapanen????? ?il?onn postharvest??????????? ?????????????? p?c ra?as????????? derliaus apdirbimas po?? lepas tuai????????? ????????????????????? post-recoltare??????????? ???????????? ???????????????????????? ??????????????????????????????????? sau thu ho?ch?? ???????????????? zangemva kwenkathi yokuvuna????????????????? C?tricos???????????? citrus??? sitrus??? ??????????????????????? agrumes?????????? ??????????????? ???????????????????? agrumecytrus?? c?trico??????????? ?????????????? narenciye????????? ???????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????