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Agriculture for Secondary Schools
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Figure 5.3 (a): Bean fly and its damage
Aphids: These are small insects that suck sap from bean plants. They cause
leaves to turn yellow, curl, and become weak. Aphids also produce honeydew,
which attracts other pests. Aphids spread viral diseases from one plant to another.
Plant-based extracts such as neem extract can reduce aphid attack on the crop.
Natural enemies like ladybirds feed on aphids and provide control. Figure 5.3 (b)
shows aphids and an infested bean leaf.
Figure 5.3 (b): Aphids and aphid-infested bean leaf
Pod borers: These are larvae that enter bean pods and eat seeds (Figure 5.3 (c)).
They cause loss by reducing the number of healthy beans. Handpicking of visible
larvae helps to lower the pest population. Pesticides are useful for controlling pod
borers; however, they should be used as recommended by agricultural extension
workers. Resistant bean varieties can also reduce infestation and damage caused
by pod borers.
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