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Disease Detection and Losses

NaCl Injury to Dormant Roadside Peach Trees and Its Effect on the Incidence of Infections by Leucostoma spp.. J. Northover, Agriculture Canada, Research Station, Vineland Station, Ontario, Canada, L0R 2E0; Phytopathology 77:835-840. Accepted for publication 5 December 1986. Copyright 1987 Department of Agriculture. Government of Canada.. DOI: 10.1094/Phyto-77-835.

Loring peach trees bordering a busy highway, which was treated repeatedly with NaCl as a deicing salt, suffered severe winter dieback of canopy shoots and greatly reduced fruit yield. Percent dead canopy wood was positively correlated with Na+ and Cl concentrations in shoot tissue, which ranged, respectively, to 6.9 and 9.0 mg/g of oven-dried tissue (ODT) and was inversely correlated with distance from the highway and with fruit production per tree. Excised Redhaven peach shoots were dipped once in NaCl solution, incubated at 2 C, rinsed, and examined for Na absorption and bud viability. Shoots that contained 6.2 mg of Na+ per gram of ODT showed severe bud mortality, and at 13.0 mg of Na+ per gram of ODT, all buds were killed. Na+ was absorbed at 90% RH but only slightly at 40% RH. Phytotoxicity was maximal after incubation at 90% RH for 8 days and was induced faster at 5 C than at 1 or 15 C. NaCl deicing salt sheared by traffic and blown into adjacent orchards was considered the principal injurious factor. Leucostoma cincta was associated with dead shoots, but it was principally a saprophytic colonist of dead tissue.

Additional keywords: canker, Cytospora, Prunus persica.