Biological control of coffee rust / Controle biológico da ferrugem do cafeeiro

AUTOR(ES)

Fernando Haddad

DATA DE PUBLICAÇÃO

2008

RESUMO

This thesis is part of a research program aiming to biocontrol coffee rust (Hemileia vastatrix, Hv) in organically-grown coffee. Efficiency of bacterial isolates was compared in two plantations, during 3 years. Isolates B157 (Bacillus sp.) and P286 (Pseudomonas sp.) reduced disease intensity relative to the control; B157 was as efficient as copper hydroxide. To define mechanism(s) of antagonism, each isolate was grown in liquid 523 Kado &Heskett medium, and six treatments were compared: i-growth broth; ii-supernatant of centrifugation; iii-centrifuged cells resuspended in saline solution; iv-cells inactivated by ultraviolet radiation; v-523 medium; and vi- saline solution. Urediniospores germination and rust severity decreased in treatments i to iii. Each isolate was applied in leaves at different concentrations and time intervals before inoculating Hv. Control efficiency decreased at the smallest concentrations and largest intervals. The isolates did not protect plants from infection by Cercospora coffeicola. Leaves were protected against Hv by applying the isolates on the same leaves Hv was inoculated; there was no protection when application and inoculation were spatially apart. B157 survival on the phylloplane was studied under greenhouse and field conditions. Bacterial suspension was spread, leaves were weekly sampled, and the number of colony forming units was assessed in a selective medium. Bacterial population decreased after 7 days of application at both conditions, steeper in the field, although colonies were recovered up to 30 days after application. Plants were sprayed with copper hydroxide (greenhouse) or copper sulphate (field), and, after 30 days, with B157 cells. Both fungicides reduced B157 population throughout time. In conclusion, Bacillus sp. B157 isolate has antibiosis to Hv and is a biocontrol agent to rust in coffee organic systems. Alternating sprays of cupric fungicides and B157 is not feasible, unless the bacterium is firstly applied in a calendar spray schedule.

ASSUNTO(S)

pseudomonas sp. controle biológico bacillus sp. ferrugem do cafeeiro coffee leaf rust biological control bacillus sp. fitopatologia pseudomonas sp. hemileia vastatrix hemileia vastatrix

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