Influence of pea‐root exudates on germination of conidia and chlamydospores of physiologic races of Fusarium oxysporum f. pisi

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Abstract
SUMMARY: Sterile root exudates from wilt susceptible and wilt resistant pea cultivars showed no differential effects on spore germination ofFusarium oxysporumSchl.f.pisi(Linf.) Snyd. & Hans, races 1 and 2 which could be correlated with the pathogenicity of a particular isolate to a given cultivar. Uniformly high percentages of germination were obtained with conidia of the two races in aseptic shake culture with exudates collected from resistant or susceptible plants of various ages. Chlamydospores of the two races incubated with exudates under sterile conditions germinated to uniformly high levels irrespective of exudate origin. Conidia and chlamydospores ofFusarium solani(Mart.) Sacc. f.pisi(Jones) Snyd. & Hans., used for comparative purposes, also germinated to high levels in the presence of exudate solutions of all cultivars.Non‐specific germination of the two races ofF. oxysporumf.pisioccurred in soil when the exudates were supplied to populations of chlamydospores via diffusion units. Germination was lower than that recorded under sterile conditions and was rapidly followed by germling lysis.