Elaboration of an early quantification method of quiescent infections of Colletotrichum musae on bananas

Colletotrichum musae, the causal agent of banana anthracnose, farms quiesce nt infections on the surface of the fruit that lead to necrosis at maturity . This work was conducted to determine a practical way to quantify the inoc ulum level that is economically practicable far routine use and applicable to immature fruit, so that it can be used as a method of early prediction a nd subsequent decision support. The method that has been developed is based on treating the fruit with 1,200 mu l of ethyIene per liter for 24 h at 25 degrees C. The fruit are then kept at 32 degrees C for 5 days, maintaining the ethylene concentration, so that conditions are optimal for revealing t he disease. The technique can be used on fruit whose age is 5 to 6 weeks af ter inflorescence emergence. A high CO2 concentration has an inhibitory eff ect on the development of lesions. The importance of the ethylene treatment on fruit maturation and breaking of appressorium dormancy is discussed, to gether with potential applications.