Anthracnose development by Colletotrichum musae was observed to be significantly less in the fruits of the banana cultivar ‘Embul’ (Mysore, AAB) infected with Phyllosticta musarum than in fruits without such infections. Anthracnose disease originates from quiescent C. musae infections in the immature fruit. P. musarum incites minute, scattered spots, referred to as freckles, in the superficial tissues of immature banana peel which do not expand during maturation or ripening. P. musarum does not appear to have a direct suppressive effect on C. musae as conidia of C. musae germinate on both freckled and non-freckled fruit forming quiescent infections. Our investigations have shown that P. musarum infection induced several defence responses in fruit including the accumulation of five phytoalexins, upregulation of chitinase and β-1,3-glucanase, phenylalanine ammonia lyase (PAL) activity and cell wall lignification. 1H and 13C NMR spectral data of one purified phytoalexin compared closely with 4′-hydroxyanigorufone. Some of the P. musarum-induced defences that retained during ripening, restrict C. musae development at the ripe stage. This paper examines the potential of P. musarum-induced defences, in the control of anthracnose, the most destructive postharvest disease in banana.

Developing banana fruits cv. 'Embul' were treated in the field with chemical elicitors, Bion ® , salicylic acid (SA) or K 2 HPO 4 at two stages, 2 and 4 or 9 and 11 weeks after bunch emergence. Fruits harvested 14-15 weeks after bunch emergence were inoculated with Colletotrichum musae, and the development of anthracnose was assessed during ripening. Treatment with Bion ® or SA at 9 and 11 weeks after bunch emergence while delaying the disease incidence significantly reduced (p < 0.05) the severity of the disease by 43 % and 65 %, respectively compared to the control. SA (500 mg/L) treatment was 22 % more effective than Bion ® (200 mg/L) while the treatment with K 2 HPO 4 (20 mg/L) increased the disease severity by 5 %. Bion ® or SA-treated fruits when challenge inoculated with C. musae after harvest showed a significantly enhanced chitinase activity (p < 0.05). There was also an increased β-1,3-glucanase activity and antifungal activity of the fruit peel compared to the controls. The elicitor treatment did not affect the fruit weight or postharvest quality.