Resumo

ALZATE VELEZ, Daniel Esteban; HOYOS CARVAJAL, Liliana Maria  e  GONZALEZ JAIMES, Elena Paola. FACTORS AFECTING THE ZOOSPORE RELEASE OF Spongospora subterranean (Wallroth)  Lagerheim f. sp. subterranea Tomlinson. Rev. Fac. Nac. Agron. Medellín [online]. 2008, vol.61, n.2, pp.4503-4510. ISSN 0304-2847.

Spongospora subterranea (Wallroth) Lagerheim f. sp. subterranea Tomlinson is the causal agent of potato powdery scab. This pathogen is worldwide distributed on the potato fields, infections occurs by zoospores which are inside resting spores called sporeballs or cystosori which are the principal way of disease spread. Sporeballs can be found on tubers, roots and soil as resistance structure, that can survive during many years until the weather conditions favor the zoospore release in order to start new infections on potato and wild host species. In this research was evaluated the temperature, cystosori inoculum source from tuber, potato roots and soil, and the effect of potato roots exudates in order to verify the conditions where the zoospore release occurs. Thus, two assays were carried out; in the first assay, the effect of water and potato root exudates were evaluated and in the second assay, was performed on potato root exudates at different inoculum sources. Mobile zoospores were counted in a Neubauer chamber during 120 hours at 24 h intervals. Both experiments showed that root exudates had a high influence in the zoospore release, the best releases were obtained between 15 and 23 °C from 48 to 96 hours. There was not difference among the inoculum sources, it means that any sporeball, if the weather conditions have been adequate, has the capacity to produce sufficient number of zoospores to start the infection process inside the host.

Palavras-chave : Roots extract; cystosori; powdery scab; potato.

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