Effects of chitosan and plant extracts on growth of Colletotrichum gloeosporioides, anthracnose levels and quality of papaya fruit

The objectives of this research were to evaluate the in vitro fungicidal effect of chitosan and aqueous extracts of custard apple leaves, papaya leaves and papaya seeds; and the combination of chitosan and plant extracts on the development of Colletotrichum gloeosporioides, which causes anthracnose on papaya. Chitosan at 2.0% and 3.0% had a fungicidal effect on C. gloeosporioides. Extracts alone did not show any fungicidal effect while the combination of 2.5% chitosan with all the tested extracts had a fungistatic rather than fungicidal effect. Changes in the conidial morphology of C. gloeosporioides were observed with 1.5% chitosan concentration after 7 h incubation. For in situ studies, control of anthracnose disease was obtained with 1.5% chitosan applied before C. gloeosporioides inoculation. Phomopsis was most frequently isolated from the non-inoculated fruit. Chitosan applications did not influence the content of total solid solubles or percentage weight loss during the storage of papaya fruit. However, there was a tendency toward greater firmness in fruit treated with the papaya seed extract alone or combined with chitosan. (C) 2003 Published by Elsevier Science Ltd.