Little leaf disease of brinjal is caused by a phytoplasma that is transmitted by
- A.Whitefly
- B.Leafhopper
- C.Honey bee
- D.Earthworm
Correct answer
Explanation
The correct answer is B, leafhopper. Phytoplasmas are bacteria without cell walls that live in the food-conducting tissue of the plant, and they are carried from plant to plant by sap-sucking leafhoppers, also called jassids; in little leaf of brinjal the leaves become very small and numerous, the plant bushes out and no fruit is set. Option A is wrong because the whitefly carries the viruses of leaf curl in cotton and chilli and of yellow vein mosaic in okra, a different group of diseases. Option C is wrong because the honey bee is a pollinator and carries no important plant pathogen of this kind. Option D is wrong because the earthworm improves soil structure and aeration and is not a vector at all. Remember the three vector pairs: whitefly with leaf curl and yellow vein mosaic, aphid with most mosaics and bunchy top, and leafhopper with the phytoplasma diseases.
Read the full article: Plant Diseases and Their Causes: Notes for Exams
Practice Questions
View allLate blight of potato is caused by which organism?
- A.A virus
- B.Phytophthora infestans
- C.Xanthomonas citri
- D.Meloidogyne incognita
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The epidemic of the 1840s destroyed the potato crop of Ireland and brought on the famine, and the study of that outbreak by Anton de Bary established plant pathology as a science.
Read the full explanation →Rust of wheat is caused by a fungus of which genus?
- A.Puccinia
- B.Ustilago
- C.Fusarium
- D.Claviceps
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The rusts of wheat, named black, brown and yellow after the colour of the pustules they raise on the stem and leaves, are caused by species of Puccinia, and resistance to them was one of the traits selected in the dwarf wheats of the Green Revolution.
Read the full explanation →Red rot, one of the most serious diseases of sugarcane, is caused by
- A.Colletotrichum falcatum
- B.Ralstonia solanacearum
- C.a phytoplasma
- D.a nematode
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The correct answer is A, Colletotrichum falcatum, a fungus that rots the internal tissue of the cane, turning it red with white patches and giving it a sour smell, and which spreads mainly through infected setts used for planting.
Read the full explanation →Citrus canker in plants is caused by
- A.a fungus
- B.a bacterium
- C.a virus
- D.a deficiency of boron
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Citrus canker is caused by a species of Xanthomonas, which enters through wounds, insect punctures and stomata and raises raised corky brown lesions, often with a yellow halo, on leaves, twigs and fruit; it spreads in splashing rain, on tools and on infected nursery plants.
Read the full explanation →Khaira disease of rice is caused by the deficiency of which nutrient?
- A.Zinc
- B.Boron
- C.Molybdenum
- D.Copper
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In khaira disease the leaves of young rice plants develop rusty brown spots that spread until the crop looks scorched, tillering is poor and growth is stunted; an application of zinc sulphate to the soil or as a foliar spray corrects it, which confirms that the cause is a deficiency…
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