Biocontrol of anthracnose on yellow passion fruits by antagonic bacteria to plant pathogens

Abstract

– In this study was evaluated the efficacy of the bacterial strains: BB-4 ( Bacillus cereus GC, subgroup B), BS-2 ( Photorhabdus luminescens ), BB- 1 ( Bacillus alcalophilus ), BS-5 ( B. cereus GC, subgroup B), BB-5 ( Stenotrophomonas maltophilia ), BB-6 ( Yersinia bercovieri ) and BS-6 ( P. luminescens ) on the control of anthracnose in yellow passion fruit, on antagonism tests and fruits tests under laboratory conditions. The plant pathogen was grown in Petri dishes containing BDA medium for 15 days and the bacterial strains were multiplied in AN medium for two days at 28°C. In passion fruits test, a wound was performed at a depth of 2 mm, followed by spraying with a suspension containing a bacterial antagonist strain (10 8 cfu. mL -1 ). On the wound, a BDA disc with 4 mm in diameter completely colonized by the pathogen and maintenance for 7 days (25oC, high RU% and 12 hours of photoperiod) until the evaluation of diameter of lesions. The experimental design adopted was the completely randomized (9 treatments and 4 replications). The data were submitted to variance analysis and Tukey test (5%). In antagonism test, only BS-5 ( B. cereus GC, Subgroup B) and BS-2 ( P. luminescens ) strains did not inhibit the mycelial growth of the pathogen. The other strains were efficient in inhibition, with levels ranging from 35% to 53%, highlighting the strains BB-4 ( B. cereus GC. Sub group B), BS-3 ( P. luminescens ) and BB-4 ( S. maltophilia ), with 52.5%, 52.5% and 53.3% of control, respectively. In the fruit test, BS-2 ( P. luminescens ), BS-5 ( B. cereus GC, Subgroup B), BB-1 ( B. alcalophilus ), BS-3 ( P. luminescens ) and BB-6 ( Y. bercovieri ) inhibited the development of the pathogen, with control levels varying between 23.4% and 43.6%, with emphasis on BB-1 ( B. alcalophilus ) and BS-3 ( P. luminescens ), with 43.6% of control, indicating potential of use on the biocontrol of anthracnose on passion fruits.