Subject: Agricultural Science

Topic: Pest and Diseases of Crop Plants

Duration: 40mins

Reference Material: Agricultural Science for Primary School, 5

Instructional Material: Pictures of some common pest e.g. squirrel, rat, weevil

Previous Knowledge: Pupils are familiar with common disease in livestock production.

Objective: At the end of the lesson, pupils should:

  • List the categories of Pest
  • Define Disease


A pest is any organism that is capable of causing damage to plants. There are different categories of pest; they are insects, pest, rodents (rat, squirrel), birds, monkeys and human pest.

Insect pest is the category of pest capable of causing the largest proportion of damage to crops. They may be categorized into two based on their mouth parts

  1. Chewing and biting mouth parts e.g. weevil, grasshopper
  2. Piercing and sucking mouth parts e.g. butterfly, mouth, cotton stainer

Disease is the alteration or deviation from normal state of health in animals or deviation from normal physiological function of the plant.

Signs/Symptoms of Disease in Plants

  • Stunted growth of plants
  • Poor or low yield
  • Physical defeats such as poor colouration and irregular stem growth
  • Premature death of plants
  • Abnormal maturity of fruits.

Disease in plants are caused by parasites or unfavourable environmental conditions.


Step 1: Teacher revises the previous lesson with the pupils.

Step 2: Teacher introduces and explains the new topic to the pupils.

Step 3: Pupils are allowed to ask questions.

Step 4: Teacher writes notes under content on the board for pupils to copy.


  1. What are Pests?
  2. Define Diseases

Conclusion: Teacher moves round for inspection, marking and correction of notes where necessary

Assignment: Agricultural science for Pry Sch, 5 Page 52, ex 4, 1 – 10