Back to: O level agriculture notes uganda
It shouldnot be translocated in plant tissues i.e it shouldnot have a residual effect which affect human life e.g DDT
It should be ozone friendly i.e should not pollute the environment
It should be harmless to the crops being sprayed
It should not be poisonous to human and other animals
It should persist in the soil to avoid frequent applications
It should not be toxic to predators,parasites and pollinators like bees that are more useful to the crop
Advantages of Chemical Pest Control
- It is a faster method of controlling crop pests in the garden
- It is more effective than other methods of pest control
- It does not reqire alo of labour compared to either mechanical or cultural
- It only applies where mechanical and cultural methods are not possibly applicable e.g topography
Disadvantages of Chemical Pest Control
- Pesticides can pollute the environment since some are non bio degradable
- Pesticides may be toxic to plants if poorly applied
- Chemicals may kill non targeted and useful organisms e.g pollinators,predators
- some chemicals may leave their residues on the crop products which may affect the farmers
- Some pests require reistance to some pesticides if they are persistently used
- Some pesticides may be poisonous to man and must be handled properly
- Technical knowledge is needed when applying the pesticides
- Chemicals are expensive and may not be afforded by small scale farmers
Ways through Which Chemicals Affect The Pests
By direct contact;This is when the chemical enters through the skin or the cuticle of a pest and then kills it
Breathing System;This is when the chemical passes through the insect breathing pores and then affect it
Ingestion;This is when pests eat some of the toxic or poisonous chemicals and die by poisoning
Sucking;pesticides which pass through the plant stream may be sucked in by insects obtining their food in this way.such pesticides are called systemic chemicals that are used to kill piercing and sucking insects like aphids
Common insect pests and their effects on crop plants
Locusts(orthoptera)
Have biting and chewing mouth parts,Adults and nymphs defoliate the plants e.g yams,casava,cereals
Termites(Isoptera)
Have biting and chewing mouth parts,eat up timber,cutdown growing plants e.g maize,citrusetc
Weavils(coleoptera)
Larva and adults bore,pupate in and feed on seed reducing grain quality e.g maize,beans,sorghum,peas etc
Maize stalk borer(lepidoptera)
Boring and chewing larva into stems,leaf sheaths and weaken the stems of maize,sugarcanes,rice etc
Army worms(lepidoptera)
Bting and chewing larva which attack and destroy large hectares with in a short period of time
Cotton stainers(hemiptera)
Have piercing and sucking mouth parts,destroy leaves and transmit viral diseases to cotton,tomatoes,maize and yams
White flies(hemiptera)
Have piercing and sucking mouth parts,distortion of leaves transmitting viral diseases to cocoa,citrus,rubber and tobacco
scale insects(hemiptera)
piercing and sucking mouth parts,feeding on cell content,folliage turns yellow and falling of young fruits
Aphids(hemiptera)
Have piercing and sucking mouth parts