SCIENCE NOTE, FOR SS2
TOPIC :DISEASES OF CROP PLANTS.
DEFINITION :A plant disease can be defined as a deviation of the plant from the normal state of health, presenting marked symptoms or outwards visible signs.
EFFECT OF PLANT DISEASE.
(1)Diseases generally reduce the yield of crops.
(2)It reduces the quality of crops.
(3)disease can lead to the death of the whole plant. (4)Reduce the income of the farmers.
SYMPTOMS OF PLANT DISEASE :
(a) chlorosis (b) Decay of plant parts (c) stunted growth (d) defoliation of Leaves.(e) lodging of stems (f) death of plants.
GENERAL CONTROL OF PLANT DISEASE. disease of crop plants can be controlled by the following methods.
(1)Cultural control (2)Biological control (3)Chemical control(4)Quarantine.
(1)CULTURAL CONTROL :This involves the use of proper agricultural practice to control plant disease. Examples, are:crop rotation,use of resistant varieties,regular weeding, fallowing etc
(2)BIOLOGICAL CONTROL. this involves the use of natural enemies to either eat up or control the disease pathogens.
(3)CHEMICAL CONTROL :This involves the use of chemicals such as fungicides, Nematicides, and Insecticides to prevent or control plant diseases. Chemical control is almost the best method of controlling plant disease irrespective of the side effect.
(1) discuss briefly the cassava mosaic disease under the following headings;
a. I) casual organisms
IV) prevention and control
V) Economic importance
B. Name 2 other diseases with similar causal organisms as cassava mosaic diseases (SSCE NOV. 1994)
describe the economic importance and the control measures of the following ;
A) Stem borer of cereal (maize)
B) Grain weevil of stored produce
C) Cotton stainer
D) Cassava mealy bug (SSCE NOV. 1992).
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