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TECHNICAL SESSION: Management of soilborne pathogens

Soil treatment options for nursery applications against plant-parasitic nematodes
Andreas Westphal - University of California Riverside, Dept. Nematology. Tom Buzo- University of California Riverside, Dept. Nematology, Daniel Kluepfel- USDA ARS, Crops Pathology & Genetics Research Unit, Zin Thu Zar Maung- University of California Riverside, Dept. Nematology

Nematode-free stock is paramount for production of perennial crops. California’s nursery certification regulations mandate sampling or prescribed cultivation patterns plus pre-plant soil treatments. Because methyl bromide is being phased out, and use of 1,3-dichloropropene (1,3-D) is restricted, alternative treatments to prevent Pratylenchus vulnus infection of nursery stock were compared to a 1,3-D control. In fall 2015, replicate microplots were drenched with one of four low-volume chemicals or three biocidal materials. In spring 2016, additional microplots of sandy or sandy loam soils were drenched with selected treatments based on the 2015 results. In fall 2016 in field plots, anaerobic soil disinfestation (ASD): incorporating easily decomposable C-sources (here: rice bran, molasses, tomato pomace or mustard seed meal), covering soil by plastic tarp and heavy watering, was evaluated. Peach rootstock ‘Nemaguard’ was planted. In the first growing season of each experiment, nematode survival was determined by nematode counts in soil and roots of the saplings. In all experiments, Salibro (experimental nematicide, Corteva), especially at high rates, ASD regardless of substrate, and one of the large-volume materials kept nematode numbers close to detection limits. Promising methods for cleaning soils from nematodes were identified but further optimizing is required to ensure the reliable high-level efficacy for the nursery industry.