Topic 3 of 7 · Form 5
Crop protection and integrated pest management
Control is justified when pest damage would cost more than the control (economic injury level).
Notes for this topic 1 file, in order
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Pests, diseases and weeds
- Insect pests: fall armyworm, stalk borers, aphids, bollworms, termites, storage weevils.
- Diseases: fungal (grey leaf spot, rusts), bacterial (bacterial wilt), viral (maize streak virus spread by leafhoppers).
- Weeds: compete for water, light and nutrients; witchweed (Striga) is a parasitic weed of cereals.
Economic thresholds
Control is justified when pest damage would cost more than the control (economic injury level).
Integrated pest management (IPM)
Combining methods to keep pests below economic levels with minimum harm:
- Cultural: crop rotation, early planting, resistant varieties, field hygiene, destroying crop residues.
- Biological: natural enemies (parasitoids, predators), biopesticides.
- Mechanical/physical: hand-picking, traps.
- Chemical: selective pesticides used only when needed, rotating modes of action to delay resistance.
- Monitoring: scouting fields regularly.
Push–pull technology
Intercropping maize with Desmodium (repels stem borers, suppresses Striga) and planting Napier grass borders (attracts borers away).
Pesticide safety
Read labels, wear protective clothing, observe re-entry and pre-harvest intervals, store safely, and dispose of containers properly.
Exam tip: In IPM questions, show how several methods work together rather than listing chemicals.
Check yourself
- What is the economic threshold?
- Give two cultural methods of controlling fall armyworm.
- Why should pesticide modes of action be rotated?
Show answers
- The pest level at which control should be applied to prevent losses greater than the cost of control.
- Any two: early planting, crop rotation, intercropping, field scouting, destroying egg masses, push–pull.
- To slow the development of pest resistance.
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