16 Sep Four major diseases of Papaya and their Management
पपीते के चार प्रमुख रोग और उनका प्रबंधन 1. Foot Rot of papaya (Pythium aphanidermatum) Foot rot is also known as collars rot or stem rot or root rot and damping off ; is the most serious disease of papaya. In India, the disease appears during the rainy season. It is more common in trees of age 2-3 years. Symptoms In case of nursery plants, damping off symptoms are produced, whereas in adult plants foot rot, collar rot symptoms are produced. Foot rot is characterized by the appearance of water soaked patches on the stem near ground level. These patches enlarge rapidly and girdle the stem, causing rotting of the tissues, which then turn dark brown or black Pathogen Causal organism: Pythium aphanidermatum Mycelium is aseptate, brown and much branched. Sporangia vesicle formed at the time of germination, zoospores 30-40 in number present within the vesicle and are born on spherical Oogonia. They germinate by producing a germ tube. The sexual spores are the oospores, born singly and moderately thick walled. Disease cycle: The pathogen is soil inhabitant and is capable of growing and surviving on the residue left in the soil where it produces abundant oospores in the decaying organic matter. Survival and spread :- Primary infection: Oospores (Pythium) in soil Secondary infection : Zoospore and Seedlings raised in infected soil carry the disease to field Favourable...