Page 122 - Agriculture_Form_3

Agriculture for Secondary Schools

(c) Keep on observing and comparing the progress in the plots in terms of
effectiveness of the weed control method used, availability of soil moisture
content, and plants development.
(d) Summarise your observations, and lessons learnt in your portfolio.
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Exercise 7.5

1. A farmer delays to weed the cowpea field. By the time the plants start to
flower, weeds have already grown tall and thick, covering most of the crop.
(a) How can this affect the growth and yield of the cowpea? (b) What should
the farmer do differently next time to control weeds better?
2. In a school project, students weed one cowpea plot using hand hoes, and
in another plot, they apply mulch to cover the soil. After four weeks, they
observe the amount of weeds and how well the plants are growing. What
differences are they likely to see between the two plots, and what might
explain those differences?

3. A field is weeded by hand every two weeks, but weeds still grow fast. What
might be done differently to reduce weed growth more effectively?

Management of pests and diseases in cowpea
Pests and diseases affect the health and yield of the cowpea crop. They can
damage leaves, flowers, pods and roots. Regular field checks, early identification
of any pests and/or diseases and proper management help to prevent serious crop
damage and losses. This section explains the most common pests and diseases in
cowpeas, how to identify them, and manage them effectively.

Common pests in cowpea and their management
Common cowpea pests include aphids, pod borers and bruchids. Knowing each
pest and how to manage it is important for increased yield.

Aphids: Aphids are the most damaging pre-flowering insect pests of cowpea.
These are small, green or black insects. They suck sap from leaves and young
shoots. Affected plants may have curled or yellow leaves. Aphids also spread viral
diseases such as the Cowpea aphid-borne mosaic virus. Aphids can be managed by
removing infected plants, spraying with soapy water, or using approved synthetic
insecticides. Figure 7.3 illustrates aphid infestation on cowpea leaves and stems.

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