A) Bacterial leaf blight of rice
B) Downy mildew of grapes
C) Loose smut of wheat
D) Black rust of wheat
Correct Answer: B
Solution :
Bordeaux mixture was discovered by Millardet in France in 1882. It is prepared by dissolving 40 g of copper sulphate and 40 g of calcium hydroxide in 5 L of water- It was first used to control downy mildew disease of grape-vine that is caused by a fungus Plasnwpara viticola. Black rust, of wheat is caused by Puccinia graminis tritici. The use of fungicide Dithane Z-78 and Dithane M-45 control the disease even at lower concentration. Loose smut of wheat is caused by Ustilago tritici. The use of fungicides (systemic fungicide like D-735 and F-461) give quite encouraging result.
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