Lesson Notes By Weeks and Term - Senior Secondary School 2

Browse through topics for Senior Secondary 2 1st, 2nd and 3rd Terms, All Weeks, All Subjects

  1. Home
  2. Lesson Notes By Weeks and Term v2 Classes
  3. Senior Secondary 2
  4. Pest of crops

Term: 2nd Term

Week: 7

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 2 periods each

Date:       

Subject:    Agriculture

Topic:-      Pest of crops

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Explain the meaning of Pests
  2. State the types of crop pests
  3. Discuss the classes of crop pests and the nature of damage they cause
  4. State the effects of crop pests on crop production

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S ACTIVITY

STEP 1

INTRODUCTION

The teacher reviews the previous lesson on crop diseases

Students pay attention

STEP 2

EXPLANATION

She explains the meaning of crop pests

She states the types of crop pests

Students pay attention and participates

STEP 3

DEMONSTRATION

She discusses the classes of crop pests and the damages caused by them

She further discusses the effects of crop pests on crop production

Students pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a summarized note on the board

The students copy the note in their books

 

NOTE

CROP PESTS

A pest can be described as any organism capable of causing damage to crop plant.

 

Types of Crop Pest.

 (i) insect

(ii) birds

(iii) rodents

(iv) monkeys

(v) man

(vi) nematodes

CLASSIFICATION OF INSECT PESTS

Insects pests can be classified into various groups based on their mode of feeding.  These groups of insect pest include:

  1. Biting and Chewing Insects: These insect (mouth-parts) which enable them to bite and chew plant    Examples include: termites, grasshoppers, leaf worms, army worms, mantids, locust, beetles, etc.
  2. Piercing and sucking insects: These insect pests posses strong mouthparts called proboscis stuck liquid from materials from plants’ tissues.  Examples include aphids, cotton strainers, mealy bugs, scale insects, capsids or mirids, white flies, etc.
  3. Burrowing insects: These insects including their larvae are capable of burrowing into plant parts and destroying the tissues of the plant or fruits or seeds.  Examples include: bean beetles, stem burrowers, maize weevils and rice weevils.

 

DAMAGES CAUSED BY PESTS

  1. Damages by Pests with Biting and Chewing Mouth Parts:

They feed by biting pieces of plant material and chewing. It may be adult or larvae of insects.

The type of damage done by them may be generalized as follows:

 (a) Loss of photosynthetic tissues; in extreme cases defoliation may result.

(b) Destruction of buds and shoots.

(c) Destruction of flowers, fruits and seeds.

(d) Boring and tunnelling of stems; interruption of sap flow and physical weakening of the stem; stem breakage may result.

(e) Eating or boring of roots and tubers in the soil.

(f) Destruction of seedlings and young plants.

(g) Formation of galls on all or any parts of the plant body.

 

  1. Damages by Pests with Piercing and Sucking Mouth Parts:

These pests have part or all of the mouthparts modified into a piercing proboscis or stylet. Sap is sucked either from the phloem or xylem or from general tissues of foliage, roots or fruits. Within this category there are two basically different types of damage.

 (a) Pests without toxic saliva:

These insects and mites remove sap, causing tissue wilt, leaf curl, stunting and in extreme condition causes death of the host plant.

(b) Pests with toxic saliva:

In this case toxic saliva causes a disproportionate amount of damage in relation to insect number. The toxins cause death of the cells and if injected into a young shoot, the entire shoot, distal to the feeding site, may die.

 

  1. Damages by Pests that are Vectors of Patho­gens:

These pests are extremely harmful, as a very small number of infective individuals may be respon­sible for severe outbreak of disease. Disease control by destruction of vectors is very difficult.

These pests are of two types:

(a) Indirect vectors:

This category includes those insects that make feeding punctures, which later becomes infected by aerial spores; this occurs in fruits, tunnelled by fruit fly larvae (Tephritidae) and fruit worms (Lepidoptera).

(b) Direct vectors:

These insects and nematodes are sometimes called ‘biological vectors’. They are responsible for active transmission, as they are often intermediate hosts. The pathogens are plant microbes, which can only be transmitted through vectors

 

PREVENTION/CONTROL OF CROP PESTS

METHODS OF PEST CONTROL

Crop pests can be prevented or controlled through the following methods:

  1. PHYSICAL CONTROL

This involves the physical removal of pests by:

  1. Hand picking of insects and larvae
  2. Setting traps to catch rodents
  3. Shooting rodents with gun
  4. Fencing round the farm with wire nets.
  5. Use of scarecrow.

 

  1. CULTURAL CONTROL

This method involves the use of farm practices to prevent or control pests, examples of cultural control are:

  1. Practicing crop rotation
  2. Use of pest resistant varieties of crops
  3. Appropriate tillage operations
  4. Burning crop residues
  5. Timely planting of crops
  6. Proper weeding or sanitation
  7. Timely harvesting
  8. Close season practices (no living plant is allowed for a certain period).

 

  1. BIOLOGICAL CONTROL

This involves the introduction of natural enemies of pests to control or keep the pest population under control. Such enemies eat up or feed on these pests, thereby reduce the population of the pests.

 

  1. CHEMICAL CONTROL

This involves the use of chemical called pesticides to control pest of crop plants. Examples of pesticides are insecticide, rodenticide, avicide etc.

Examples of chemicals used to control pests are:

  1. Insecticides – for controlling insect pest e.g grasshopper
  2. Rodenticides – chemical control for rodents such as rats
  • Avicides – for controlling bird pest
  1. Nematicides – chemical used to control nematodes. E.g worms

 

EVALUATION:   1. Explain the meaning of crop pests

  1. State the types of pests
  2. Outline the classes of pests and the nature of damage                              they cause
  3. Highlight some prevention and control measures                              against pests

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively