Resumo

SALAZAR PELAEZ, Lina María; PATINO HOYOS, Luis Fernando  e  BUSTAMANTE ROJAS, Elkin. FOLIAR SUBSTRATES FOR INCREASING CHITINOLYTIC AND GLUCANOLYTIC BACTERIA ON PHYLLOSPHERE OF BANANA. Rev. Fac. Nac. Agron. Medellín [online]. 2006, vol.59, n.2, pp.3449-3465. ISSN 0304-2847.

Black Sigatoka, caused by the fungus Mycosphaerella fijiensis Morelet, is considered the economically most important disease of banana and plantain crops. Its control has been based on the use of synthetic fungicides, whose mode of action becomes overcome by the fungus populations. This research explored the possibility of developing a biological regulation strategy based on the study and manipulation of certain biotic and abiotic factors that interact in the phyllosphere of the banana, with the objective of increase the natural populations of chitinolytic and glucanolytic bacteria, which could negatively affect the germination process of M. fijiensis.  On the basis of a previous phase of this study in which a partial chemical and microbiological characterization in the phyllosphere of banana and plantain crops under conditions of Uraba-Antioquia (Colombia), was conducted here 14 foliar substrates were evaluated that consisted of colloidal chitin (CC) [4%], barley flour (BF) [2,5%] and urea (U) [1%], individually or in a combination, always with a mineral base and attachment-dispersant solutions.  Those substrates that had a combination of BF and U yielded higher increases in the epiphytic lytic bacterial populations, with counts exceeding 10.000 fold with respect to their their initial populations on banana leaves of the 'Grande naine' variety and 8,6 y 15 fold higher in populations of chitinolytic and glucanolytic bacteria, respectively, with respect to the population without foliar substrate treatments. The effect of rainfall on bacteria populations and the necessity of adjusting a formulation that improves the possibilities of foliar substrates for black sigatoka control are discussed.

Palavras-chave : Phyllosphere; Mycosphaerella fijiensis; Black Sigatoka; biological control.

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