Abstract

GILCHRIST, Elizabeth; JARAMILLO VILLEGAS, Sonia  and  REYNALDI, Sebastián. EFFECT ON THE POWDERY SCAB OF FOUR ISOLATES OF THE FUNGUS Trichoderma asperellum IN THREE TYPES OF SOILS. Rev. Fac. Nac. Agron. Medellín [online]. 2009, vol.62, n.1, pp.4783-4792. ISSN 0304-2847.

The protozoan Spongospora subterranea f. sp. subterranea is an obligate parasite that replicates in roots and tubers of potato causing the powdery scab. This disease has disseminated on a global scale, because the commercial traffic of infected tubers used as seed and the absence of effective treatments. The present work investigated the effects of four isolates of Trichoderma asperellum in three soil types: Andisol, Entisol and Inceptisol. The soils were infected with 1942 ± 226 cystosori per gram of soil. It was used Solanum tuberosum variety Diacol Capiro. No differences were observed between treated and non treated plants with T. asperellum. The root surface affected by galls was an average of 2.2 %, and no significant differences (p<0.05) were observed among the soils. The reduction of plant growth was of 41, 32 and 28 % for the Andisol, Entisol and Inceptisol, respectively. The reduction in tubers production was of 40, 28 and 0,1% for the Andisol, Entisol and Inceptisol, respectively. Similar percent of root surface covered with galls resulted in production reduction of 40%, but also of 0,1%, indicating the necessity of other methods to determine the infection severity. The growth and production reductions were inversely associated with the Al³⁺ concentration in the soils, suggesting that powdery scab effects are strongly related to soil characteristics.

Keywords : Spongospora subterranea; Solanum tuberosum; potato production; plant growth; cystosori.

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