Secreted chitinase involved in the degradation of chitin, a component of the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods). Participates in the infection process and directly acts in the penetration process of the host cuticle (By similarity). Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Belongs to the glycosyl hydrolase 18 family. Chitinase class III subfamily.