Management of Pests and Diseases

seed initiative


Management of Pests and Diseases

What are Pests?

Pests are organisms (weeds, insects, animals) that cause damage to crops. They affect the plant’s growth and vigour, reduce yields and may even kill the plant.


Types of Pests
• Insects- Aphids, beetles, caterpillars,
• Insect-like organisms –mites, spiders
• Weeds
• Molluscs- Snails and slugs
• Vertebrates- Birds
• Mammals- Rats and Mongoose


How Do Pests Damage Plants
Pests cause damage to Plant roots, stems, leaves, flowers, fruits and seeds.

Insects are the most common pests.
Eaten, damaged, distorted or discoloured plant parts may be a sign of insect damage. The nature of the damage is determined by the mouthparts of the insects.


Three (3) Types of Mouth Parts:

MOUTHPARTS & ACTION: Biting and Chewing
PEST: Caterpillars, Beetles
• Ragged edges of leaves.
• Pieces of plant tissue missing
• Irregular holes in foliage or stem
• Missing leaves
• Leaves with “window panes” i.e. .showing bared veins (called leaf skeletonizing)
• Discoloured areas on the surface or margins of leaves or petals
• Wilted plants (from white grub damage or other root feeders).


MOUTHPARTS & ACTION: Piercing and Sucking
PEST: Aphids, Whiteflies
• Small dots on the surface of frits and leaves
• Leaf curling
• Deformed or stunted plants
• Wilting and ultimately tissue death
• Growth of black sooty mold fungus
• Some piercing and sucking insects can also inject toxic materials into the plants while feeding and some transmit disease organisms


MOUTH PARTS & ACTION: Rasping and scraping
PEST: Thrips, Mites
• Areas of discoloured tissue as if rubbed with sandpaper
• Silvery bronze leaf colour after the insect removes the top layer of the cells and sucks the cell contents
• Death of affected tissue which turns brown and tears easily
• Bleached and dry leaves


Video –Pest Management


Information courtesy the Extension Training and Information Services (ETIS) Division

Ministry of Agriculture, Land and Fisheries

Sign up for updates

Be in the know. Receive email notifications on the activities of the Ministry of Agriculture, Land and Fisheries.

New to our website?

We’ve grouped information on our website under helpful categories to make your experience easier.