PATH 372 Diseases of Horticultural Crops
PATH 372 Diseases of Horticultural Crops
PATH 372 Diseases of Horticultural Crops
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Survival and spread<br />
P.I: Soil and on infected onions as stromata<br />
S.I: Wind borne conidia<br />
Favourable conditions<br />
Wet soils with a temperature <strong>of</strong> 26 0 C<br />
Management<br />
Resistant varieties: Nasik red, Pusa Ratna, Pusa Red<br />
Protection <strong>of</strong> bulbs from rains after harvest<br />
Dry bulbs properly before storage by hot air at 37 – 48 0 C<br />
Spray zineb or captan @0.2% before harvest <strong>of</strong> crop<br />
3) Smut – Urocystis cepulae<br />
Symptoms<br />
Fungus attacks cotyledons <strong>of</strong> young plants soon after their emergence causing<br />
dark, elongated eruptive spots<br />
On older leaves, the lesions may extend from base to the tip and appear as blisters<br />
Lesions develop into thickened areas <strong>of</strong> several mm in size<br />
Lesions burst open releasing masses <strong>of</strong> black smut spores<br />
Severely affected plants killed within 3-4 weeks <strong>of</strong> emergence<br />
Surviving plants are stunted with stout, brittle, distorted leaves bearing lesions<br />
throughout their length<br />
Numerous blisters appear on leaves and bulb scales <strong>of</strong> mature plants which rupture<br />
to expose masses <strong>of</strong> black powdery spores<br />
Survival and spread<br />
P.I: Spore balls in infected soil<br />
S.I: Wind blown soil and surface drianage water, onion bulbs and onion transplants<br />
Favourable conditions<br />
Optimum temperature <strong>of</strong> 10-20 0 C<br />
Plant is susceptible for 2-3 weeks from the DOS<br />
Management<br />
ST with thiram@3 g/Kg seed<br />
Crop rotation and use <strong>of</strong> disease free seedlings<br />
Cultivar, Hardy white bunching is resistant<br />
Spray with captan or ferbam @0.2% along with a sticker<br />
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