Major Diseases of Maize and Groundnuts

Form 2 Agriculture Lessons for JCE: Grow Your Knowledge

UNIT 12: Major Diseases of Maize and Groundnuts

A disease is any deviation from the normal functioning or health of an organism.

Fungal Diseases: Caused by fungi; attack plant parts like leaves, stems, and roots.
Viral Diseases:
- Symptoms:
  - Chlorosis (yellowing of leaves).
  - Stunted growth.
  - Mosaic mottling (leaf spots).
  - Necrosis (death of plant tissues, e.g., leaves).
  - Leaf curls.
Bacterial Diseases: Caused by bacteria.

Name of Disease	Crop	Cause	Symptoms	Control Methods
Streak	Maize	Virus	White/yellow lines parallel with leaf veins (variegation). Stunted growth. Half-filled cobs.	Plant disease-resistant varieties. Control aphids. Early planting.
Head Smut	Maize	Fungus	Black powdery masses covering cobs and tassels. Severely dwarfed plants.	Plant clean seeds. Crop rotation. Roguing (removing diseased plants).
Blight	Maize	Fungus	Brown patches on leaves and cobs.	Plant disease-resistant varieties.
Stalk Rot	Maize	Bacteria	Discoloration of leaves and sheath. Decomposition of the stalk.	Deep ploughing to incorporate crop residues. Avoid sprinkler irrigation.
Cob Rot	Maize	Fungus	White fungal growth covering the cob or individual grains.	Use certified seeds. Plant disease-resistant varieties.
Rosette	Groundnuts	Virus	Leaf variegation. Small curling of leaves. Profuse development of small leaves. Stunted growth.	Early planting. Close spacing of plants.
Early Leaf Spot	Groundnuts	Fungus	Brown spots surrounded by a yellow circle/halo.	Practice crop rotation. Apply sulfur dust every 2 weeks. Use disease-resistant varieties.
Late Leaf Spot	Groundnuts	Fungus	Dark to brown spots without a halo.	Use disease-resistant varieties. Apply sulfur dust.
Bacterial Wilt	Groundnuts	Bacteria	Sudden wilting of stems and leaves in young plants. Leaves on dead plants remain green. Drying branches curl.	Practice crop rotation. Use certified seeds. Use disease-resistant varieties.

Diseases significantly impact agricultural production, leading to:

Loss of Quantity: Reduced total yield.
Loss of Quality: Deterioration in appearance, nutritional value, or market grade.
Loss of Income: Due to lower yields and reduced market value.
Increased Production Costs: Due to expenses on chemicals, resistant varieties, and disease management.

Cultural Methods:
- Crop Rotation: Breaks the life cycle of disease-causing organisms.
- Destroying Crop Residues: Burning or burying deeply to eliminate pathogen sources.
- Planting Resistant Varieties: Using crops naturally less susceptible to specific diseases.
- Roguing: Uprooting and destroying diseased plants to prevent spread to healthy crops.
- Ploughing the Field: Can bury pathogens and reduce inoculum.
- Early Planting: Allows crops to establish and develop natural resistance before peak disease pressure.
- Use of Clean Planting Materials: Ensures no pathogens are introduced with seeds or vegetative parts.
- Correct Spacing: Improves air circulation, reducing humidity around plants, which can inhibit fungal diseases.
Biological Methods:
- Involves using one living organism to inhibit the activity of a living plant pathogen (e.g., beneficial microbes).
Legislative Procedures:
- Laws and Regulations: Used to prevent the introduction of new pests/diseases into an area or to control the spread of existing ones.
- Routine Inspection: All exported agricultural products are inspected at immigration points.
- Quarantine: Imported goods suspected of infection or infestation are isolated.