Lesson Notes By Weeks and Term v4 - SHS 2
HEALTH ISSUES IN CROP PRODUCTION
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HEALTH ISSUES IN CROP PRODUCTION
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Agriculture
Class: SHS 2
Term: 2nd Term
Week: 7
Grade code: 2.4.1.LI.2
Strand code: 4
Sub-strand code: 1
Content standard code: 2.4.1.CS.1
Indicator code: 2.4.1.LI.2
Theme: AGRICULTURE AND HEALTH
Subtheme: HEALTH ISSUES IN CROP PRODUCTION
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Welcome, future agriculturalists! Today, we are exploring a topic that every farmer in Ghana, from the backyard gardener in Accra to the large-scale cocoa farmer in the Ahafo Region, must understand: Health Issues in Crop Production. Just like humans get sick, plants also suffer from diseases and attacks from pests. These issues can drastically reduce the amount of food we can grow (yield), affect the quality of our produce, and lead to significant financial loss for our farmers and the nation. Understanding what causes these problems is the first and most important step in learning how to manage them effectively.
This section breaks down the core content you need to master. We will study pests and diseases separately. Part A: Crop Pests
A crop pest is any organism (usually an animal, most often an insect) that causes physical damage or economic loss to crops. Pests can attack any part of the plant—roots, stem, leaves, flowers, or fruits—and can strike at any stage, from seedling to storage.
Classification of Crop Pests
While there are many ways to classify pests (e.g., by the part of the plant they attack), the most practical method for a farmer is by their mode of feeding. This tells us *how* they damage the plant and helps us choose the right control method. Biting and Chewing Pests How they feed: These pests have strong mouthparts called mandibles, which they use to bite off, chew, and swallow parts of the plant. Damage caused: You will see holes in leaves, skeletonized leaves (only veins are left), bored holes in stems and fruits, or entire seedlings cut at the base. Ghanaian Examples: Grasshopper/Locust: Attacks maize, rice, and vegetables. It chews large pieces of leaves, often leaving only the midrib. This reduces the plant's ability to photosynthesize, stunting its growth and reducing yield. Caterpillar (e.g., Armyworm): The larval stage of moths and butterflies. Armyworms move in large groups and can destroy an entire maize farm overnight by chewing the leaves and tassels. Variegated Grasshopper (*Zonocerus variegatus*): A major pest of cassava and various vegetables. It eats the leaves, causing severe defoliation. Piercing and Sucking Pests How they feed: These pests have specialised, needle-like mouthparts called a proboscis or stylet. They use this to pierce the plant's tissue (epidermis) and suck out the nutrient-rich sap from the phloem. Damage caused: The direct damage is the loss of nutrients, leading to yellowing of leaves (chlorosis), stunted growth, wilting, and distorted leaves or fruits. Crucially, they are also major vectors for spreading viral diseases from one plant to another. Ghanaian Examples: Aphids: Tiny, soft-bodied insects found in colonies on the underside of leaves of crops like garden eggs, pepper, and cabbage. They suck sap, causing leaves to curl and yellow. They also secrete a sticky "honeydew" which encourages the growth of black sooty mould. Mealybugs: Pests of cocoa, pineapple, and cassava. They are covered in a white, waxy substance. The Cocoa Mealybug is a notorious vector for the Cocoa Swollen Shoot Virus Disease (CSSVD). They suck sap from pods and shoots, weakening the tree. Whiteflies: Tiny, white, winged insects that fly up in a cloud when disturbed. They are serious pests of cassava and tomatoes, sucking sap and transmitting viral diseases like the Cassava Mosaic Virus. Boring Pests (Borers) How they feed: The larvae (grubs or caterpillars) of these pests tunnel or bore into the stems, roots, fruits, or seeds of plants, feeding from the inside. Damage caused: Their feeding activity is hidden, making them difficult to control. They weaken the plant's structure, causing stems to break (lodging), fruits to rot, and stored grains to be destroyed. Ghanaian Examples: Maize Stem Borer: The caterpillar larva of a moth bores into the maize stem. It disrupts the flow of water and nutrients, causing the central shoot to die ("deadheart") and the stem to break easily in the wind. Bean Weevil: A storage pest. The adult lays eggs on cowpea or other beans. The larva hatches and bores into the seed, eating the inside and leaving a hollow shell with a characteristic exit hole. This makes the beans unfit for consumption or planting. Yam Tuber Beetle: This beetle bores into yam tubers while they are still in the ground, creating tunnels and reducing the quality and market value of the yam.