Black leaf streak (Mycosphaerella fijiensis) is the most threatening disease of bananas, causing losses in production and fruit quality. This study evaluated a black leaf streak management strategy involving foliar applications of nutritive substrates in order to increase the beneficial phylloplane population of lactic acid and chitinolytic bacteria. The three treatments included efficient microorganisms (EM), two “Biols” whose composition included shrimp heads for the promotion of chitinolytic bacteria (Biol 1) and a second (Biol 2) without shrimp heads for stimulating the growth of lactic acid bacteria. The plants treated with Biol 1 had the best growth of chitinolytic bacteria and did not have a significant increase in the disease severity. The Biol 2 increased, but not significantly, the lactic acid bacterial population at the end of the six-week evaluation period and had a significant increase in the disease severity. The correlation between bacterial population and disease severity was not statistically significant (p>0.05).