Table of Contents

Review of Second Term Scheme of Work Agricultural Science Primary 5 Third Term Lesson Notes Week 1

Understanding Weeds, Pests, and Their Impact on Farming

Introduction

Weeds and pests are two major challenges that farmers face in crop production. While weeds compete with crops for essential nutrients, pests cause significant damage that reduces crop yield. Understanding how to control these agricultural challenges is crucial for maintaining a healthy farm.

In this comprehensive guide, we will explore weeds, their effects, benefits, and control measures. We will also delve into crop pests, their classifications, damages they cause, and effective pest control methods. Whether you’re a student, teacher, or an aspiring farmer, this blog post will provide valuable insights into the world of weeds and pests.

Week 2: What Are Weeds?

Definition of Weeds

Weeds are unwanted plants that grow where they are not needed, particularly in farmlands. These plants compete with crops for water, sunlight, and nutrients, affecting overall productivity.

Common Weeds on the Farm

Some common weeds found in farms include:

Spear grass (Imperata cylindrica)
Goat weed (Ageratum conyzoides)
Waterleaf (Talinum triangulare)
Elephant grass (Pennisetum purpureum)
Wild sunflower (Tithonia diversifolia)

Creating a Weed Album

A weed album is a collection of different weed samples with their names, descriptions, and pictures. This helps students and farmers identify and understand various weeds found on farms.

Week 3: Effects of Weeds on Farmers

Weeds can cause serious problems for farmers, affecting crop growth and increasing production costs.

Negative Effects of Weeds

Competition for Nutrients – Weeds absorb essential nutrients meant for crops, leading to poor yield.
Reduction in Soil Moisture – They take up water from the soil, leaving crops dehydrated.
Spread of Diseases – Some weeds harbor pests and diseases that attack crops.
Increased Labor and Costs – Farmers spend money and time removing weeds to maintain farm productivity.
Lower Crop Quality – Weeds can make harvesting difficult and contaminate food products.

Solutions to Weed Problems

Timely Weeding – Removing weeds before they mature helps control their spread.
Use of Herbicides – Selective herbicides can help control specific weed species.
Crop Rotation – Planting different crops in cycles can prevent weed dominance.
Mulching – Covering the soil with plant materials suppresses weed growth.

Week 4: Control of Weeds

Weeds can be controlled using different methods, including manual, chemical, and biological approaches.

Methods of Weed Control

Manual Weeding – This involves uprooting weeds by hand or using simple tools like hoes and cutlasses.
Mechanical Weeding – Machines such as tractors and weeders are used to clear large areas.
Chemical Control – Herbicides like glyphosate and paraquat help kill weeds quickly.
Biological Control – Natural weed enemies such as insects or fungi can help suppress weeds.

Importance of Weed Control

Promotes healthy crop growth
Reduces pest and disease outbreaks
Increases farm productivity
Lowers farming costs in the long run

Practical Weed Control in School Farms

Students can actively participate in controlling weeds by removing them from school farms or gardens. This serves as hands-on training in agricultural practices.

Week 5: Benefits of Weeds

Although weeds are mostly seen as harmful, they also have some benefits.

How Weeds Benefit Animals and Humans

Animal Feed – Some weeds like elephant grass serve as food for livestock.
Medicinal Use – Certain weeds like bitter leaf (Vernonia amygdalina) are used in traditional medicine.
Soil Improvement – Some weeds add organic matter to the soil when decomposed.
Food for Humans – Some edible weeds like waterleaf are used in cooking.

Week 6: Pests and Diseases of Crops

Definition of Crop Pests

Crop pests are organisms that feed on crops and cause significant damage. They include insects, rodents, and birds.

Types of Insect Pests

Piercing and Sucking Insects – These insects suck sap from plants, weakening them. Examples include aphids and whiteflies.
Burrowing and Boring Insects – These insects damage crops by creating holes in stems and roots. Examples include stem borers and weevils.

Week 7: Mid-Term Test and Break

Students can use this period to revise key topics and prepare for assessments.

Week 8: Classification of Insect Pests

Classification Based on Mouthparts

Chewing Pests – These pests bite and chew plant parts. Examples: Grasshoppers, caterpillars.
Piercing and Sucking Pests – These pests suck plant sap. Examples: Aphids, mealybugs.
Boring Pests – These pests bore into stems and fruits. Examples: Stem borers, fruit flies.

Why Classification is Important

Helps in identifying the right control methods
Prevents unnecessary pesticide use
Promotes sustainable pest management

Week 9: Damages Caused by Pests

How Pests Damage Crops

Eating Plant Parts – Some pests feed on leaves, stems, and roots.
Transmitting Diseases – Insect pests spread viruses and fungi.
Reducing Crop Quality – Damaged crops fetch lower prices in the market.

Preventing Pest Damage

Use pest-resistant crop varieties
Monitor crops regularly
Apply biological or chemical control methods

Week 10: Control of Insect Pests

Methods of Pest Control

Use of Pesticides – Chemicals like insecticides kill pests quickly.
Biological Control – Using natural enemies of pests, such as ladybugs to eat aphids.
Cultural Practices – Crop rotation and proper spacing reduce pest attacks.
Physical Control – Setting traps and handpicking pests.

Advantages and Disadvantages of Biological Control

✅ Advantages:

Environmentally friendly
Does not leave harmful residues
Sustainable

❌ Disadvantages:

Slower than chemical methods
Requires careful monitoring

Practical Pest Control on School Farms

Students can participate in pest control exercises such as setting traps, applying pesticides, or using organic methods.

Conclusion

Weeds and pests are major challenges in agriculture, but with proper management, farmers can minimize their negative effects. Understanding how to identify, classify, and control these agricultural threats is essential for better crop production.