Effect of ammonium carbonate and sodium bicarbonate on anthracnose of papaya

Colletotrichum gloeosporioides is the causal organism of anthracnose in Carica papaya L. (papaya, papaw). The effect of ammonium carbonate (3%) or sodium bicarbonate (2%) in aqueous solution or when incorporated into a wax formulation on anthracnose severity in inoculated or naturally infected fruits was examined. Both salts had significant effects, but that of ammonium carbonate was greater than that of sodium bicarbonate in controlling anthracnose. Ammonium carbonate (3%) incorporated into the wax formulation effectively reduced anthracnose incidence by 70% in naturally infected papaya and extended the storage life by maintaining the firmness, color and overall quality of the fruit in low temperature storage (13.5degreesC) and 95% r.h. for 21 days followed by 2 days under marketing conditions. The mode of action of ammonium carbonate on the control of anthracnose appears to be via complete inhibition of radial mycelial growth and conidia germination.