Lesson Note on Diseases of Crops: Meaning and Common Crop Diseases for SS 2

Class: Senior Secondary School 2 (SS2 / SSS2)
Term: First Term
Week: 5
Age: 16 years
Duration: 45 minutes
Subject: Agricultural Science
Curriculum Theme: Crop Production
Previous Lesson: Forest Management: Meaning and Management Techniques.
Topic: Diseases of crops
Subject Matter: Meaning of crop diseases, diseases of major crops (cereals, legumes, beverages, tubers)

Specific Objectives

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

Cognitive Domain:

• Define crop diseases.
• Identify common symptoms of crop diseases.
• List examples of diseases affecting major crops.

Affective Domain:

• Appreciate the economic importance of identifying crop diseases early.
• Develop interest in methods of preventing crop diseases.

Psychomotor Domain:

• Observe and describe symptoms on diseased crop samples.
• Distinguish between healthy and diseased crop parts.

Social Domain:

• Discuss with peers the impact of crop diseases on food security.
• Collaborate during field observations to identify diseased crops.

Reference Materials

The following resources were used in planning this lesson:

• Senior Secondary Schools Education Curriculum
• State Unified Scheme of Work
• Essential Agricultural Science for Senior Secondary Schools

Instructional Materials

The teacher will teach this lesson with the aid of:

• Diseased crop samples (e.g., leaves with spots, mouldy grains)
• Pictures of common crop diseases
• Storage grains sample
• Hand lens

Rationale for the Lesson

Understanding crop diseases helps pupils recognize symptoms and the various pathogens that affect crops. This knowledge is important for implementing effective control measures, which ultimately contributes to better crop yields and food security.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of different types of crops and their importance from previous lessons.

Lesson Content/Board Summary

Diseases of Crops

Meaning of Crop Diseases

Crop diseases are harmful conditions caused by living organisms (pathogens) or environmental factors that affect the normal growth, development, and yield of crops. They often lead to visible symptoms like spots, wilting, or rotting.

Types of Crop Diseases Based on Causal Agents (Pathogens)

• Fungi: Cause diseases like rusts, smuts, mildews, and blights.
• Bacteria: Cause bacterial blights, wilts, and soft rots.
• Viruses: Cause mosaic patterns, leaf curling, and stunted growth.
• Nematodes: Microscopic roundworms that attack roots, causing galls and poor nutrient uptake.

Diseases of Major Crops

The following are common diseases affecting major crops:

• Cereals (e.g., Maize, Rice, Wheat):
  • Smut: Caused by fungi, forming black powdery masses on grains or ears.
  • Rice Blast: Caused by a fungus, leading to lesions on leaves, stems, and panicles.
  • Leaf Rust: Caused by fungi, appearing as reddish-brown pustules on leaves.
• Legumes (e.g., Groundnut, Cowpea):
  • Cercospora Leaf Spot: Caused by a fungus, resulting in dark spots with light centers on leaves.
  • Groundnut Rosette: Caused by a virus, leading to stunted growth, yellowing, and small leaves.
• Beverages (e.g., Cocoa, Coffee):
  • Cocoa Black Pod: Caused by a fungus, resulting in blackening and rotting of cocoa pods.
  • Coffee Leaf Rust: Caused by a fungus, appearing as yellow-orange powdery spots on the underside of leaves.
• Tubers (e.g., Cassava, Yam):
  • Cassava Mosaic Virus: Caused by a virus, leading to yellowing and distortion of leaves, and stunted growth.
  • Bacterial Blight: Caused by bacteria, causing angular leaf spots, wilting, and stem dieback.

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, reviews the previous lesson briefly, and then introduces the new topic by asking pupils to observe some provided diseased crop samples.
Pupils’ Activity: Pupils respond to greetings, recall the previous lesson, and observe the samples.
Learning Point: Pupils are prepared for the new lesson and their interest is aroused.

Step 2: Meaning of Crop Diseases

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains the meaning of crop diseases and introduces the concept of pathogens as causal agents, providing simple examples.
Pupils’ Activity: Pupils listen attentively, ask questions for clarity, and define crop diseases in their notes.
Learning Point: Pupils understand what crop diseases are and their primary causes.

Step 3: Identification of Symptoms

Time: 7 minutes
Teaching Skill: Observation/Demonstration
Teacher’s Activity: The teacher guides pupils to observe the provided diseased crop samples and pictures, helping them identify and describe various symptoms like leaf spots, wilting, and mould.
Pupils’ Activity: Pupils observe the samples and pictures, describing the symptoms they see and discussing them with peers.
Learning Point: Pupils can identify and describe common symptoms of crop diseases.

Step 4: Diseases of Cereals and Legumes

Time: 7 minutes
Teaching Skill: Elaboration/Listing
Teacher’s Activity: The teacher discusses specific diseases affecting cereals (e.g., smut, rice blast, leaf rust) and legumes (e.g., cercospora leaf spot, groundnut rosette), explaining their key characteristics.
Pupils’ Activity: Pupils listen, ask questions, and take notes on the diseases and their symptoms.
Learning Point: Pupils learn about diseases specific to cereal and legume crops.

Step 5: Diseases of Beverages and Tubers

Time: 7 minutes
Teaching Skill: Elaboration/Listing
Teacher’s Activity: The teacher continues by discussing diseases of beverage crops (e.g., cocoa black pod, coffee leaf rust) and tuber crops (e.g., cassava mosaic virus, bacterial blight).
Pupils’ Activity: Pupils pay attention, contribute to discussions, and record information in their notebooks.
Learning Point: Pupils learn about diseases specific to beverage and tuber crops.

Step 6: Field Observation/Mouldy Grains

Time: 5 minutes
Teaching Skill: Practical Application
Teacher’s Activity: The teacher shows samples of mouldy storage grains and discusses storage conditions that encourage disease, emphasizing the importance of safe handling and proper storage.
Pupils’ Activity: Pupils observe the mouldy grains, identify the mould, and discuss factors contributing to storage diseases.
Learning Point: Pupils understand practical aspects of disease identification and prevention in storage.

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. What is a crop disease?
2. Mention two types of pathogens that cause crop diseases.
3. List two diseases that affect cereal crops.
4. Describe one symptom of Cassava Mosaic Virus.

Pupils’ Activity: Pupils answer orally and in writing.
Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson and assigns homework: “Research and write down two methods for controlling one crop disease discussed today.”
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: The lesson is concluded with a clear understanding of the topic.

Lesson Keywords

• Crop diseases – Harmful conditions affecting crops.
• Pathogens – Organisms that cause disease (e.g., fungi, bacteria, viruses).
• Smut – A fungal disease of cereals forming black powdery masses.
• Rice Blast – A fungal disease causing lesions on rice plants.
• Black Pod – A fungal disease causing rotting of cocoa pods.
• Mosaic Virus – A viral disease causing mottled or distorted leaves.
• Blight – A disease causing rapid browning, wilting, and death of plant tissues.

Differentiation

For struggling learners, the teacher will provide simplified diagrams and focus on identifying only two major diseases. Advanced learners will be encouraged to research disease life cycles or specific control measures for selected diseases beyond the scope of the lesson.

Note for teachers using this lesson plan

Teachers should ensure that crop samples are handled with care and disposed of properly after the lesson. Emphasize safety during any practical observation activities. Encourage pupils to relate the diseases discussed to crops grown in their local environment.