#rust disease

A plant-pathogenic fungus causes rust disease, generally lacks asexual spores and produces sexual spores externally on a

Rust fungi such as Puccinia are Basidiomycetes. Karyogamy and meiosis occur in a basidium, and basidiospores are produced externally on it.

Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Fungi - Phycomycetes Ascomycetes Basidiomycetes