Term: 2nd Term
Week: 8
Class: Senior Secondary School 2
Age: 16 years
Duration: 40 minutes of 2 periods each
Date:
Subject: Agriculture
Topic:- Weeds and weeds control
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
- Explain the meaning of weeds
- List the various types of weeds and their botanical name
- State the effects of weeds on crops and the economy
- Describe the various measures of controlling weeds
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
INSTRUCTIONAL PROCEDURES
PERIOD 1-2
PRESENTATION
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TEACHER’S ACTIVITY
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STUDENT’S ACTIVITY
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STEP 1
INTRODUCTION
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The teacher reviews the previous lesson on crop pests
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Students pay attention
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STEP 2
EXPLANATION
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She explains the meaning of weeds
She lists the various types of weeds and their botanical names
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Students pay attention and participates
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STEP 3
DEMONSTRATION
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She discusses the effects of weeds on the crops and the economy
She further discusses the control measures for weeds
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Students pay attention and participate
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STEP 4
NOTE TAKING
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The teacher writes a summarized note on the board
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The students copy the note in their books
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NOTE
WEEDS AND WEEDS CONTROL
Weeds are unwanted plants.
SOME COMMON WEEDS AND THEIR BOTANICAL NAMES
- Bahama grass (Cynodon dactylon)
- Siam weed (Chromolaena odorata)
- Spear grass (Imperata cylindrica)
- Dayflower (Commelina benghalensis)
- Nutgrass (Cyperus rotundus)
- Milkweed (Euphorbia heterophylla)
- Guinea grass(Panicum maximum)
- Cogon grass(Imperata cylindrical)
- Wild sunflower(Aspilia Africana)
- Centro(Centrosema pubescens)
- Waterleaf(Talinum triangulare)
- Carpet grass (Axonopus compressus)
EFFECTS OF WEEDS ON CROPS AND THE ECONOMY
- Weeds compete with crops for space
- Weeds compete crops for sunlight
- Weeds compete with crops for Nutrients: the root of weeds rapidly develop and remove considerable proportion of the available plant nutrients thereby reducing the healthy growth of the plants.
- Weeds harbor Crop Pest and Diseases
- Weeds compete with crops for soil moisture: their root is capable of developing fast and removing a large portion of the soil moisture required for the normal growth of the plant.
- The combined competition of weed and crops eventually will result in low yield.
- Weeds compete with crops for soil Oxygen
- The quality of harvested crops will reduce and this will affect market values of such crops .
- Losses in income of the farmer
- Some weeds are toxic to farm animals : the leaves and stem of some weeds contain toxins which may be dangerous to farm animals .
WEEDS CONTROL
Weeds can be controlled through a number of methods
- Mechanical /physical method
This includes
- Hand pulling /hand picking: this involves uprooting of weeds from the soil by hand.
- Hoeing : this involves uprooting weeds from the soil by using hoe
- Slashing : through this method, the Arial part of the weeds are removed with cutlass leaving behind the root in the soil
- Rotary cultivation: this involves using hand drawn implements to undertake the ploughing and burying of weeds.
- Biological control : this involves the introduction of some insects and herbivores animals to farmland to eat up the leaves of these weeds
- Cultural control: this involves the practice of crop rotation and the growth of cover crops to suppress the growth of weeds on the farmland.
The cultural methods of weed control are
- Flooding
- Burning
- Mulching
- Cover cropping
- Crop rotation
- Chemical control: this involves the use of chemical solutions called herbicides to control the growth of weeds.
EVALUATION: 1. Explain the meaning of weeds
- State some common weeds and their botanical names
- Outline the effects of weeds on the crops and the economy
- Highlight some control measures against weeds
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively