Lesson Note on Pests and Diseases of Crops: Definition and Classification for SSS 2

Class: Senior Secondary School 2 (SS2 / SSS2)
Term: Second Term
Week: 2
Age: 16 years
Duration: 45 minutes
Subject: Biology
Curriculum Theme: Applied Biology / Agricultural Biology
Previous Lesson: Conservation of Natural Resources: Importance and Methods.
Topic: PEST AND DISEASES OF CROPS
Subject Matter: Definition of pest, classification of pest by the parts of plants they attack (stem borers, root feeders, leaf feeders, fruit and seed feeders), invertebrate pests (nematodes, arthropods, locust), vertebrate pests (birds, mammals), crop diseases, their agents, and control methods.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

• Define agricultural pests and crop diseases.
• Classify pests based on the parts of plants they attack.
• Identify various invertebrate and vertebrate pests with examples.
• State the agents responsible for common crop diseases.
• Outline different methods for controlling pests and diseases.

Affective Domain:

• Appreciate the economic importance of controlling pests and diseases in agriculture.
• Develop an interest in practical methods of crop protection.
• Recognize the impact of pests and diseases on food security.

Psychomotor Domain:

• Participate in creating a table showing the relationship between crop diseases, their agents, and control methods.
• Identify different pests and disease symptoms from visual aids.

Social Domain:

• Collaborate effectively with peers during discussions about pest and disease management.
• Share ideas and examples of pests and diseases affecting local crops.

Reference Materials

The following resources were used in planning this lesson:

• Senior Secondary Schools Education Curriculum
• State Unified Scheme of Work
• Modern Biology for Senior Secondary Schools
• https://www.biologyonline.com/dictionary/pest
• https://www.fao.org/plant-protection/en/

Instructional Materials

The teacher will teach this lesson with the aid of:

• Textbook
• Posters showing various pests and diseased crops
• Charts illustrating classification of pests
• Pictures of crops damaged by pests and diseases

Rationale for the Lesson

This lesson helps pupils understand the various organisms and conditions that harm crops, which is important for ensuring food supply. Learning about pests and diseases and their control methods enables pupils to contribute to better agricultural practices and improve crop yield.

Prerequisite/Previous Knowledge

Pupils have some basic knowledge of plants, their parts, and the importance of agriculture from previous lessons in Basic Science or earlier Biology classes.

Lesson Content/Board Summary

Pests and Diseases of Crops

Definition of Pests

A pest is any organism that causes damage to crops, livestock, or human property, or that is otherwise annoying or harmful to humans. In agriculture, pests are organisms that reduce the yield or quality of crops.

Classification of Pests by Parts of Plants Attacked

Pests can be classified based on the specific parts of the plant they feed on or damage:

• Stem Borers: These pests bore into the stems of plants, blocking nutrient and water transport.
  • Examples: Maize stem borer, Sugarcane borer.
• Root Feeders: These pests attack the roots, impairing the plant’s ability to absorb water and nutrients.
  • Examples: Nematodes (e.g., root-knot nematodes), Termites, Sweet potato weevil larvae.
• Leaf Feeders: These pests chew on or suck sap from leaves, reducing photosynthesis and overall plant vigor.
  • Examples: Grasshoppers, Caterpillars, Aphids, Whiteflies, Leaf miners.
• Fruit and Seed Feeders: These pests damage the fruits and seeds, which are often the commercially valuable parts of the plant.
  • Examples: Fruit flies, Weevils (e.g., bean weevil, maize weevil), Birds.

Classification of Pests by Type

Pests can also be broadly classified into invertebrate and vertebrate categories:

• Invertebrate Pests: These are pests without a backbone.
  • Nematodes: Microscopic roundworms that live in the soil and attack plant roots.
    • Examples: Root-knot nematodes, Cyst nematodes.
  • Arthropods: A large group including insects, mites, and spiders.
    • Examples: Locusts, Grasshoppers, Aphids, Caterpillars, Beetles, Mites, Weevils.
  • Molluscs: Soft-bodied invertebrates.
    • Examples: Snails, Slugs.
• Vertebrate Pests: These are pests with a backbone.
  • Birds: Feed on seeds, fruits, and young seedlings.
    • Examples: Weavers, Quelea birds, Sparrows.
  • Mammals: Larger animals that feed on various plant parts.
    • Examples: Rats, Mice, Bush pigs, Monkeys, Rabbits.

Crop Diseases

Crop diseases are conditions that impair the normal functioning of a plant, leading to reduced growth, yield, or quality. They are often caused by living organisms called pathogens or by adverse environmental conditions.

Agents of Crop Diseases (Pathogens)

The main agents causing crop diseases are:

• Fungi: Cause diseases like rusts, smuts, mildews, blights, and wilts.
• Bacteria: Cause bacterial blights, soft rots, and cankers.
• Viruses: Cause mosaic diseases, leaf curls, and stunting.
• Nematodes: While also pests, some nematodes cause specific disease symptoms like root galls.

Common Crop Diseases, Their Agents, and Control Methods

The following table summarizes some common crop diseases, their causative agents, and general control measures:

General Methods of Pest and Disease Control

Effective control involves a combination of methods:

• Cultural Control: Practices like crop rotation, proper spacing, timely planting, sanitation (removing infected plant parts), and resistant varieties.
• Biological Control: Using natural enemies (predators, parasites, pathogens) to control pests.
• Chemical Control: Application of pesticides (insecticides, fungicides, herbicides, nematicides).
• Physical/Mechanical Control: Hand-picking pests, trapping, weeding, fencing, scarecrows.
• Quarantine: Preventing the entry or spread of pests and diseases to new areas.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to recall some common problems farmers face when growing crops. The teacher then introduces the topic: “Pests and Diseases of Crops.”
Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively to the introduction of the new topic.
Learning Point: Pupils are reminded of the importance of crop health and are introduced to the lesson’s focus.

Step 2: Definition of Pests

Time: 7 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher defines what a pest is in an agricultural context and asks pupils to give examples of common pests they know.
Pupils’ Activity: Pupils listen to the definition and contribute examples of pests they have observed or learned about.
Learning Point: Pupils understand the definition of an agricultural pest.

Step 3: Classification of Pests by Parts of Plants Attacked

Time: 8 minutes
Teaching Skill: Illustration/Classification
Teacher’s Activity: The teacher explains and illustrates, using charts and posters, how pests are classified based on the parts of plants they attack, providing examples for each category (stem borers, root feeders, leaf feeders, fruit/seed feeders).
Pupils’ Activity: Pupils observe the charts, listen to the explanations, and ask questions for clarification.
Learning Point: Pupils can classify pests based on the plant parts they damage.

Step 4: Classification of Pests by Type

Time: 7 minutes
Teaching Skill: Explanation/Categorization
Teacher’s Activity: The teacher further classifies pests into invertebrate (nematodes, arthropods, molluscs) and vertebrate (birds, mammals) groups, giving specific examples for each.
Pupils’ Activity: Pupils identify different types of pests and their examples.
Learning Point: Pupils differentiate between invertebrate and vertebrate pests.

Step 5: Crop Diseases and Agents

Time: 7 minutes
Teaching Skill: Explanation/Discussion
Teacher’s Activity: The teacher defines crop diseases and explains that they are caused by pathogens (fungi, bacteria, viruses, nematodes). The teacher guides pupils to mention common crop diseases and their observed symptoms.
Pupils’ Activity: Pupils define crop diseases and identify common disease symptoms they have seen.
Learning Point: Pupils understand what crop diseases are and their causative agents.

Step 6: Methods of Control

Time: 5 minutes
Teaching Skill: Collaboration/Table Creation
Teacher’s Activity: The teacher discusses various methods of pest and disease control (cultural, biological, chemical, physical/mechanical, quarantine). The teacher then guides pupils to create a simple table showing crop diseases, their agents, and appropriate control methods.
Pupils’ Activity: Pupils participate in the discussion and contribute to filling out the table with examples.
Learning Point: Pupils learn about different ways to control pests and diseases.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. Define an agricultural pest.
2. List three classes of pests based on the parts of plants they attack, giving one example for each.
3. Mention two invertebrate and two vertebrate pests.
4. State one common crop disease, its causative agent, and two control methods.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 1 minute
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of pest and disease control for food production.
Pupils’ Activity: Pupils listen to the summary and prepare for the next lesson.
Learning Point: Pupils reinforce their understanding of the topic.

Lesson Keywords

• Pest – An organism that causes damage to crops or property.
• Disease – An abnormal condition impairing plant function.
• Pathogen – A microorganism (e.g., fungus, bacterium, virus) that causes disease.
• Stem Borers – Pests that bore into plant stems.
• Leaf Feeders – Pests that consume plant leaves.
• Nematodes – Microscopic roundworms that can be plant pests or disease agents.
• Arthropods – Invertebrate animals with an exoskeleton, segmented body, and paired jointed appendages (e.g., insects).
• Vertebrates – Animals with a backbone (e.g., birds, mammals).

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research and present on specific pest outbreaks or disease epidemics in Nigeria. For pupils needing more support, the teacher can provide simplified diagrams, re-explain concepts using more relatable examples, or pair them with peers for collaborative learning during table creation.

Note for teachers using this lesson plan

Teachers should ensure to bring actual examples or clear pictures of damaged crops and various pests to make the lesson more practical and engaging. Encourage pupils to share their observations from local farms or gardens. Emphasize the economic implications of pest and disease control on food security and farmer livelihoods.