Page 47 - Agriculture_Form_3

Agriculture for Secondary Schools

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Figure 3.2 (a): Quelea birds in a sorghum field

Stem borers: These are insect pests that tunnel inside the sorghum stem and
make holes that weaken the plant. As a result, the plant becomes weak and falls.
Stem borers can be identified by checking for small holes in the stem and weak,
drooping plants. The pest can be managed by removing and destroying infected
plants, encouraging natural enemies (e.g., birds), and practising crop rotation to
break their life cycle. Figure 3.2 (b) shows the sorghum stem borer larva and a
damaged plant.

Figure 3.2 (b): Sorghum stem borer and a damaged plant

Aphids: These are small insects that suck sap from sorghum plants, causing
leaves to curl, turn yellow, and dry out. They also release a sticky liquid called
honeydew, which attracts ants and increases the risk of disease infestation. Aphids
can be identified by looking for tiny green, black or brown insects on leaves and
stems. They can be controlled by applying plant-based extracts such as neem

38 Student’s Book Form Three

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AGRICULTURE F3.indd 38 17/09/2025 14:11