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Diseases of Tobacco and their Management | Aspirant view

Diseases of Tobacco and their Management | Aspirant view Thank you for reading... Learn something every day... The following diseases are discussed in this video Damping off Damping off: Pythium aphanidermatum Symptoms  Seedlings get infected at any stage in the nursery  Sprouting seedlings are infected and wither before emergence from the soil (Pre-emergence damping-off)  Water soaked minute lesions appear on the stems near the soil surface, girdling the stem, spreading up and down in the stem ; stem rot leading to toppling over of the seedlings (Post-emergence damping off) Management • Prepare raised seed beds with adequate drainage facility. • Burn the seed beds with paddy husk before sowing. • Drench the seed bed with 1 per cent Bordeaux mixture or 0.2 per cent Copper oxychloride, two days before sowing. Avoid over crowding of seedlings by using recommended seed rate (1 to 1.5g/2.5m2). • Avoid excess watering of the seedlings. • Spray the nursery beds two weeks after sowing with 1 per cent Bordeaux mixture or 0.2 per cent Copper oxychloride or 0.2 per cent Mancozeb and repeat subsequently at 4 days interval under dry weather and at 2 days interval under wet cloudy weather or Spray 0.2 per cent Metalaxyl at 10 days interval commencing from 20 days after germination Frog eye spot: Cercospora nicotianae Symptoms  Small ashy grey spots with brown border appear on lower leaves  The typical spots has a white centre, surrounded in succession by grey and brown portions, surrounded by a dark brown to black margin, resembling the eyes of a frog  Several spots coalesce to form large necrotic areas, causing the leaf to dry up from the margin and wither prematurely. Powdery mildew: Erysiphe cichoracearum var. nicotianae Symptoms Small, white isolated patches appear on the upper surface of the leaves and stem Later, it spreads fast and cover the entire lamina Affected leaves turn brown, wither and scorched and defoliation occurs Black shank: Phytophthora parasitica var. nicotianae Symptoms  Roots and base of the stem gets infected  Black discolouration of stem; blackening of roots  When the affected stem is split open, the pith region is found to be dried up in disc- like plates showing black discolouration Wild fire: Pseudomonas tabaci Symptoms  In nursery, dark brown to black spots with a yellow halo spreads quickly causing withering and drying of leaves  In advanced stage, the entire leaf is fully covered with enlarged spots with yellow halos  The leaves slowly wither and dry and the entire plant gives a blighted appearance Mosaic: Tobacco Mosaic Virus (TMV) Nicotiana virus I (Marmor tabaci var. vulgare) Symptoms  Light discoloration along the veins of the youngest leaves  Leaves develop a characteristic light and dark green pattern  Dark green areas develop into irregular crumpled swellings or blisters  Leaves puckered, thin and malformed  Dark brown necrotic spots develop under hot weather and this symptom is called “Mosaic burn” or Mosaic scorching”  The virus is sap transmissible Phanerogamic parasite: Broom rape (Orobanche cernua var. desertorum)  It is a total parasite  Affected plants are stunted and show withering and drooping of leaves leading to wilting