Theory question 106
Crop Pests(a) Distinguish between a field pest and a storage pest.
(b) Give two reasons for early harvesting of maize from the field.
(c) Describe each of the following methods of crop improvement: (i) introduction; (ii) cross breeding.
(d) List six factors that should be considered in selecting a crop variety for your locality.
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(a) A field pest attacks crops while they are growing on the farm (e.g. stem borer, grasshopper); a storage pest attacks harvested produce in store (e.g. weevils, grain moth, rats).
(b) Any two: to avoid field pests such as weevils and birds; to avoid theft; to avoid rotting/mould in wet weather; to free the land for the next crop; to sell early at higher prices (green maize).
(c)(i) Introduction: bringing in a crop variety from another area or country, testing it and adopting it if it does well (acclimatisation).
(ii) Cross breeding: mating (crossing) two different varieties with desired traits so that offspring combine the good qualities of both; selection follows.
(d) Any six: yield potential; resistance to pests and diseases; maturity period; adaptability to local climate and soil; market demand/consumers' taste; storage quality; availability of planting material; drought tolerance; nutritive value.
Give examples of each kind of pest in (a).