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Components in Unbleached Commercial Chitin Stimulate Pythium ultimum in Sugarbeet Spermosphere. Daniel Gindrat, Plant Pathologist, Changins Federal Agricultural Research Station, CH-1260 Nyon, Switzerland; Phytopathology 66:312-316. Accepted for publication 28 August 1975. DOI: 10.1094/Phyto-66-312.

Severe pre-emergence damping-off occurred when sugarbeet seeds coated with commercial chitin were planted in soils either naturally or artificially infested by Pythium ultimum. Uncoated seeds were not damaged in two of three infested soils. In noninfested soils, coated seeds were not damaged. No pre-emergence damping-off occurred when seeds were coated with bleached chitin, then planted in infested soil. Glucose and nitrogenous compounds were found in the water extract of unbleached chitin. Unbleached chitin, its water extract, as well as glucose and peptone, stimulated germination of sporangia of P. ultimum in pure culture both in the presence and absence of natural soil. Bleached chitin did not stimulate germination of sporangia under the same conditions. Sporangia germinated more rapidly, and in greater numbers in the spermosphere of sugarbeet seeds coated with unbleached chitin, than in that of uncoated seeds. It is suggested that unbleached chitin applied to seeds provides nutrients that increase the germination of sporangia of P. ultimum in the spermosphere, and enhance subsequent colonization of the seeds by the pathogen.

Additional keywords: biological control, seed exudates.