Term: 2nd Term
Class: Senior Secondary School 2
Age: 16 years
Duration: 40 minutes of 2 periods each
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
The teacher reviews the previous lesson on crop pests
Students pay attention
She explains the meaning of weeds
She lists the various types of weeds and their botanical names
Students pay attention and participates
She discusses the effects of weeds on the crops and the economy
She further discusses the control measures for weeds
Students pay attention and participate
The teacher writes a summarized note on the board
The students copy the note in their books
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 can be controlled through a number of methods
- Mechanical /physical method
- 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
- 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