Theory question 105
Crop Diseases(a) List four ways by which diseases are spread on a crop farm.
(b) State three symptoms and three control measures of each of the following diseases: (i) onion twister; (ii) root-knot of tomato
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(a) Any four: wind; rain splash and water; insects and other vectors; infected seeds and planting materials; farm tools and machines; man and animals; infected soil and plant debris
(b)(i) Onion twister (fungus): symptoms – twisting and curling of leaves; yellowing and drying of leaves; poor bulb formation/stunting. Control – crop rotation; plant healthy/treated sets and seeds; fungicide sprays; remove and burn infected plants
(ii) Root-knot of tomato (nematode): symptoms – swellings (galls/knots) on roots; wilting in the heat of the day; stunting and yellowing; low yield. Control – crop rotation with non-host crops; nematicides/soil fumigation; resistant varieties; fallowing; flooding; uproot and burn infected plants
Three symptoms and three controls for each disease.