Title Pathology Part-4.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Plant Pathology 5 th Edition 2024
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Sugarcane Red rot - Colletotrichum falcatum Symptoms:  The first external symptom appears mostly on third or fourth leaf which withers away at the tips along the margins.  Typical symptoms of red rot are observed in the internodes of a stalk by splitting it longitudinally. These include the reddening of the internal tissues which are usually elongated at right angles to the long axis of the stalk.  The presence of cross-wise white patches are the important diagnostic character of the disease.  The diseased cane also emits acidic-sour smell. As the disease advances, the stalk becomes hollow and covered with white mycelial growth. Favourable Conditions:  Monoculturing of sugarcane.  Successive ratoon cropping.  Water logged conditions and injuries caused by insects. Management:  Soak the setts in 0.25% Agallol or Aretan solution for five minutes.  Setts can be treated with aerated steam at 52°C for 4 to 5 hours and by moist hot air at 54°C for 2 hours. Smut: Ustilago scitaminea Symptoms:  It is a culmiculous smut. It affects the stalk of cane.  Severe from April to July, 10% loss in juice.  The affected plants are stunted and the central shoot is converted into a long whip-like, dusty black structure. It is also known as “Whip smut”. Management:  Discourage ratooning of the diseased crops having more than 10 per cent infection.

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 4 Ratoon stunting - Clavibacter xyli sub sp. xyli (Rickettsia Like Organism - RLO) Symptoms:  Diseased clumps usually display stunted growth, reduced tillering, thin stalks with shortened internodes and yellowish foliage. Pink vascular bundles in shades of yellow at the nodes are seen in the infected canes. Minor diseases  Damping-off - Pythium aphanidermatum, P. debaryanum, P. graminicola, P.ultimum  Downy mildew - Peronosclerospora sacchari  Rust - Puccinia erianthi  Gummosis - Xanthomonas axonopodis pv. Vasculorum , the fibro-vascular becomes red  Sugarcane Mosaic - Sugarcane mosaic potyvirus Turmeric Rhizome Rot - Pythium graminicolum Symptoms:  Starting from the margins the leaves get dried up, collar region of pseudo stem becomes soft and water-soaked and plants collapse. The rhizomes decay as a result of the attack of the fungus.