Lesson Notes By Weeks and Term - Senior Secondary School 2

Name of Disease

Causal Organism

Method of Transmission

Symptoms and Economic Importance

Prevention and Control Measures

Maize Snut

Fungus (ustilago maydis)

Air borne Fungus spores deposited on fruits

   i.     Reduced yield

ii.     Galls on ears, leaves and tarsels which later turn black

    i.     Destroy diseased plant.

  ii.     Use resistant varieties

iii.     Seed treatment.

Rice Blight

Fungus (piricularia oryzae)

Airbone spores on leaves

   i.     Small longitudinal red spots on leaves which turn

    i.     Use clean seeds

  ii.     Avoids heavy use of nitrogen fertilizers

iii.     Use resistant varieties

Maize Rust

Fungus (puccinia polysora)

Airborne spores deposited on leaves

   i.     Red spots on leaves

ii.     Reduced yield

iii.     Death of the crop

    i.     Early planting

  ii.     Crop rotation

iii.     Use resistant varieties

Cercopora a leaf spot of cowpea

Fungus

Thr20ough wild

   i.   Reddish brown spots on leaves

ii.   Lesions on leaves

iii.   Chlorosis

iv.   Dropping or falling of leaves

      i.         Spray with fungicides

     ii.         Crop rotation

   iii.         Plant resistant varieties

Rosette disease of groundnut

Virus

By piercing and sucking insect (Aphid).

   i.   Yellow leaves with mosaic mottling.

ii.   Stunted plant with curled leaves.

iii.   Wilting and death of plant

iv.   Shortening of the internodes

      i.         Early planting

     ii.         Crop rotation

   iii.         Use insecticides

   iv.         Uproot and burn infected plants

     v.         Use resistant variety.

Cassava Mosaic

Virus

i.      Through piercing and sucking insect (whitefly) (Bemisia nigerensis)

ii.      Infected plant cutting

i.     Mottling of leaves

ii.     Mosaic pattern on leaves

iii.     Stem/leaf distortion

iv.     Stunted plant

v.     Reduction in yield

  i.     Use resistant varieties

ii.     Uproot and burn infected plant

iii.     Spray with insecticides to kill vector

iv.     Use disease free stem cutting

v.     Farm sanitation.

Leaf blight of cassava

Bacterium xanthomonas manihotis

i.     Infected cutting

ii.     Rain splashing

iii.     Insects

iv.     Tools

i.     Blighting   of leaves

ii.     Wilting of plant

iii.     Falling off lf leaves

iv.     Reduced yield

v.     Canker of stem

vi.     Die-back of stem

i.     Use resistant varieties

ii.     Use disease free cutting

iii.     Early planting

iv.     Practise crop rotation

Cocoa black pod disease

Fungus phytophthora palmivora

i.     Rain splash

ii.     Insects

i.     Brown spots on pod

ii.     Rottening of pods.

iii.     Entire pod turns black

iv.     Low yield

i.     Remove and destroy infected pods.

ii.     Regular weeding

iii.     Spray with fungicides e.g. Bordeaux mixture.

iv.     Avoid overcrowding of cocoa plant.

Coffee Leaf rust

Fungus

i.     By wind

ii.     By rain splash

i.   Yellow or brown spot on leaves

ii.   Orange powdery mass on the leaf

iii.   Reduction in yield

iv.   Dropping of leaves

    i.  Plant seeds from healthy plants.

  ii.  Use resistant varieties

iii.  Spray with copper fungicides

Black arm (bacterial blight of cotton)

Bacterium

i.     Through leaves

ii.     Stems near the ground

i.     Angular spots on leaves

ii.     Boll rot

iii.     Exudates from affected leaves

iv.     Retarted growth and death of plant

i.     Seed dressing

ii.     Uproot and burn infected plants

iii.     Use resistant varieties

iv.     Crop rotation

Root knot of tomato/okro Damping off disease of okra

Nematode

Fungus

Nematodes in soil

Infected soil

  i.  Knotting or galling or roots

ii.  Retarded growth

iii.  Early death of plant

iv.  Reduction in yield

v.  Retarted growth

vi.  Cells becomes water logged

vii.  Gradual wilting of plants

viii.  Death of plant

   i.     Soil sterilization

  ii.     Crop rotation

iii.     Use resistant varieties

iv.     Uproot and burn infected plants

  v.     Spray with copper fungicide

vi.     Use resistant varieties

vii.     Sterilization of soil

Onion twister disease

Fungus

      i.         Infected soil

     ii.         Water splash

   iii.         Infected bulb.

i.   Twisting of leaves

ii.   Grey patches on leaves

iii.   Reduction in yield

iv.   Death of plant

i.   Crop rotation

ii.   Use resistant varieties

iii.   Spray with fungicides

iv.   Early planting

Stored produce mould

Fungus

      i.         Infected seed or fruits

     ii.         High humidity

   iii.         By soil

i.   Black mould on seeds and fruits

ii.   Pungent smell

iii.   Sour taste

iv.   Decay of seeds and fruits in store

i.   Proper drying of seed before storage

ii.   Spray with fungicides

iii.   Maintain low humidity in store

iv.   Remove contaminated seeds before storage.