Page 108 - Agriculture_Form_3

Agriculture for Secondary Schools

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Figure 6.5 (b): Downy mildew symptoms on a common pea plant

Fusarium wilt: This is a soil-borne fungal disease. It causes yellowing of leaves
and wilting, even when soil moisture is sufficient. The disease affects plant roots
and blocks the movement of water. To control Fusarium wilt, crop rotation must
be practised, and repeated planting of peas in the same area must be avoided. The
use of wilt-resistant common pea varieties is recommended. Fungicides may be
applied where necessary, with advice from a field expert or experienced farmer.
Figure 6.5 (c) shows a wilted pea plant with yellow leaves caused by Fusarium
wilt.

Figure 6.5 (c): Fusarium wilt symptoms on a common pea plant

Common pea mosaic virus disease: This is a viral disease spread by aphids. It
causes leaves to become mottled with green and yellow patches. Affected leaves
are often curled and smaller than normal. The affected plant shows stunted growth,
reduced pod size and number. Management of the disease requires the use of
virus-free seeds. Infected plants must be removed from the field and destroyed.
Control of aphids is essential to stop the spread of the virus. Figure 6.5 (d) shows
mottled, curled leaves on a plant affected by the common pea mosaic virus.

Student’s Book Form Three 99

17/09/2025 14:12
AGRICULTURE F3.indd 99 17/09/2025 14:12
AGRICULTURE F3.indd 99