Abstract

GUEDEZ, Clemencia; CANIZALEZ, Luis Miguel; CASTILLO, Carmen  and  OLIVAR, Rafael. Mycoflora of two organic substrates and its effect on the control of Rhizoctonia solani Kühn. Agron. colomb. [online]. 2009, vol.27, n.3, pp.395-399. ISSN 0120-9965.

The use of organic manures for root disease control, which results from the remarkable diversity of microorganisms that interact there, has led to consider them as part of biological control strategies. In this context, we evaluated the mycological diversity of two organic substrates, (organic soil and vermicompost) and their effect on the control of the fungus Rhizoctonia solani. The mycoflora of the two organic substrates was assessed through Warcup's soil plate method, which allowed identifying the fungi and counting the number of colonies. The most abundant isolates were grown against R. solani in dual cultures. The results allowed identifying 16 isolates belonging to three orders and eight genera of fungi, including Penicillium sp., Aspergillus sp., Fusarium sp. and Trichoderma harzianum Rifai. A significantly more abundant mycoflora (P≤0.05) was found in the vermicompost substrate. In the dual cultures, T. harzianum attained a higher pathogen inhibition percentage (P≤0.05) than the other fungi. The vermicompost substrate did not determine the growth of new fungi, but enhanced the development of the pre-existing native ones. Not only having shown the best results in controlling R. solani, but also the most vigorous growth among the identified fungi, T. harzianum comes up as a promissory biological controller of the pathogen, that can be incorporated to the soil during its preparation.

Keywords : biological control; antagonism; soil fungi; vermicompost.

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