State two symptoms and two control measures of the following plant diseases: (a) cassava mosaic; (b) groundnut rosettes; (c) root-knot of okra; (d) bacterial blight of cotton
Explanation
(a) Two symptoms of cassava mosaic diseases are: (i) Mottling of leaves/mosaic pattern on leaves (ii) Stem and leaf distortion. Two control measures are: (i) Using resistant varieties (ii) Spraying with insecticides to kill vector.
(b) Two symptoms of groundnut rosette diseases are: (i) The leaves become yellow with mosaic form of mottling. (ii) Stunted growth with curled leaves. Two control measures are: (i) Early planting (ii) Up rooting and burning infect plants
(c) Two symptoms of root knot disease of okra: (i) Unusual knotting or galling of certain cells of roots (ii) Retarded growth. Two control measures are: (i) Practice crop rotation (ii) Use resistant varieties
(d) Two symptoms of bacteri blight of cotton are: (i) Presence of angular spots on leaves and branches (ii) The boll will rot. Two control measures are- (i) Use resistant varieties (ii) Seed dressing with Agroson 5w.