Important Pests And Diseases In Agriculture (Economic Importance)


Table Of Contents

  • Description Of Pests Of Crops
  • Types Of Crop Pest
  • Classification Of Insect Pests
  • Effects Or Economic Importance Of Insect Pests In Crop Production
  • Prevention And Control Of Pests
  • Diseases Of Crop
  • Causes Of Crop Diseases
  • General Effects Of Diseases On Crop Production
  • General Control Of Plant Diseases
  • Summary Of General Control Measures Of Diseases Of Crops

Important Pests And Diseases In Agriculture

Pests Of Crops: A pest can be described as any organism capable of causing damage to crop plant.

Types Of Crop Pest

Important pests of crop plants are grouped into the following classing:

1. Insects
2. Birds
3. Rodents
4. Monkeys
5. Man
6. Nematodes.

Classification Of Insect Pests

These can be classified into various groups based on their mode of feeding. These groups of insect pests include:

1. Biting and chewing insects,
2. Piercing and sucking insects,
3. Boring insects.

1. Biting and chewing insects: These insect pests possess strong mandible and maxillae (mouth-parts) which enable them bite and chew plant parts. Examples include: termite, grasshoppers, leaf worms, army worms, mantid, locusts, beetles etc.

2. Piercing and sucking insects: These insect pests posses strong mouth-parts called proboscis which enable them to pierce through plants and suck liquid materials from plants tissues. Examples include: Aphids, cotton stainers, mealybugs, scale insects, capsids or mirids, white flies etc.

3. Boring insects: These insects, including their larvae, are capable of boring into plant parts and destroy the tissues of the plant, fruits or seeds. Examples include: bean beetles, stem borers, maize weevils and rice weevils.

Effects or Economic Importance Of Insect Pests In Crop Production

1. Insect pests destroy crops in the field through their biting, chewing, boring, sucking and defoliation activities.

2. They cause reduction in the viability of stored produce.

3. Site of injuries by insects may predispose crops to disease attack.

4. They increase the cost of production during the course of controlling them.

5. They render vegetables and fruits unattractive and unremarkable.

6. Some are carriers or vectors of diseases.

7. The profits of farmers are reduced.

Prevention And Control Of Pests

Pests of crops can be prevented or controlled through the following methods:

1. Physical control
2. Cultural control
3. Biological control
4. Chemical control

1. Physical control: This involves the physical removal of pests by:

i. Hand-picking of insects and larvae,

ii. Setting traps to catch rodents,

iii. Shooting rodents with gun,

iv. Fencing round the farm with wire nets.

2. Cultural control: This method involves the use of farm practices to prevent or control pests especially on the field. Examples of cultural control include:

i. Bush fallowing
ii. Crop rotation
iii. Change in the time of planting
iv. Regular weeding
v. Bush burning

3. Biological control: Biological control involves the introduction of the natural enemies of pests to control or keep the pests population under control.

4. Chemical control: Chemical control involves the use of chemicals called pesticides to control pests of crop plants. Examples are:

i. Pesticides: chemicals to control pests.

ii. Insecticides: chemicals to control insects.

iii. Rodenticides: chemicals to control rodents.

iv. Avicides: chemicals to control birds.

v. Nematicides: chemicals to control nermatodes.

Diseases Of Crop

A plant disease may be defined as a departure or deviation of the plant from the normal state of health, presenting marked symptoms or outward visible signs.

Causes Of Crop Diseases

Diseases of crops are caused by the following agents:

i. Viruses
ii. Bacteria
iii. Fungi
iv. Nermatodes
v. Nutrient deficiency

General Effects Of Diseases On Crop Production

Diseases of crop plants can be controlled through cultural control, biological control and chemical control.

1. Chemical Control: Cultural control involves the use of crop rotation, resistant varieties, tillage practices, regular weeding, fallowing, timely planting, pruning, uprooting, burning of infected crops etc to control or prevent diseases.

2. Biological Control: Biological control involves the use of natural enemies of the disease to reduce or totally eliminate the disease.

3. Chemical control: Chemical control involves the use of chemicals such as fungicides, nematicides, insecticides to dust or spray plants and plant materials in order to prevent or control plant diseases.