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Reduction of potato wart disease with crushed crabshell: suppression or eradication?

Hampson, M.C., Coombes, J.W.
Canadian journal of plant pathology 1995 v.17 no.1 pp. 69-74
infection, Solanum tuberosum, Synchytrium endobioticum, soil fungi, soil amendments, cultural control, soil bacteria, soil properties, soil pH, soil water content, incidence, soil temperature, ammonia, free-living nematodes, application rate, disease control, plant diseases and disorders
Synchytrium endobioticum, the causal agent of potato wart disease, is present in the soils of most communities and settlements in Newfoundland. Potato varieties immune to the disease reduce outbreaks. The pathogen, however, survives in soil for decades, and eradication by biotoxic chemicals in these communities is not environmentally acceptable. Crushed crabshell, found to suppress the disease without phytotoxicity, was tested for its short-term eradicant potential. Soils were amended at 0%, 4%, and 8% crabshell (w/w). Changes in selected physical (temperature, pH), chemical (ammonia), and biological parameters (bacteria, nematodes) and pathogen populations were measured. Striking changes occurred in bacterial and nematode populations following the incorporation of crabshell, peaking at many thousand-fold of the starting numbers. Although pathogen populations and disease incidences were reduced in all treatments, the long-term potential of crabshell as an eradicant remains, nevertheless, unproven.