Plant pests and diseases

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Plant pests and diseases

A grasshopper. Image credit nutrainigridients.com

A grasshopper. Image credit nutrainigridients.com

ZIMSEC O Level Integrated Science Notes: Plant pests and diseases

  • In the wild there is a balance in nature.
  • The are few pests and diseases that destroy plants.
  • In crop plants there are more pests that cause and spread disease.
  • This is because there will be more plants of the same type concentrated together.
  • As a result pests can feed, multiply and spread easily from one plant to another.
  • Agriculture is constantly under threat unless people are aware of pests, the diseases they cause and the measures of controlling them.
  • A pest is any organism, plant or animal which is harmful to people and their activities.
  • There are different types of pests.
  • Some cause damage to crops by eating them, others are very small and they are only seen by the damage they cause.
  • The damage caused by pests results in reduced plant productivity.
  • The yields of fruits and seeds may be reduced by pests.
  • Thus effective pest control is important.
Tissue eating pestsSap sucking pestsBacterial wilt diseaseFungal rust disease
Type: Cutworms, grubs, locusts and grasshoppers, larvae and caterpillars,beetles, crickets, slugs, snails, millipedes.Type: Red spider. Very small and often abundantType: the organisms are microscopic.Type: the disease is caused by microscopic fungi which live in the stems and leaves of plants
Symptoms: holes, gaps, cut edges to plant organs. The damage is caused by pests eating plant roots, stems and leaves. Slugs, snails and millipedes eat roots and young shoots.Symptoms: damage reflected by spots on leaves and stem, wilting and premature drop. Often young seedlings and lawns, ( tufts, brown patches, death)Symptoms: damage caused includes: browning of shots and a slimy oozing when the stem is cut. Plans affected include: tomato, potato, sunflower and tobacco.Symptoms: evidence is the appearance of different sized pustules on the surface ( orange or yellow). Crops affected many cereal crops like maize, sunflower and beans.
Control: Carbaryl/8 SS. Snail baitControl: Lime sulphur in water or Kelthane HF or Dimethoate 40 EC.Control:little, apart from improving drainage, using good seed and rotating cropsControl: Dithane M45 or using resistant variables. Isolation of infected plants and crop rotation

Credit: Focus on Science Book 3

To access more topics go to the Integrated Science Notes page.

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By | 2017-01-17T11:18:18+00:00 August 12th, 2015|Notes, O Level Science Notes, Ordinary Level Notes|1 Comment

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He holds an Honours in Accountancy degree from the University of Zimbabwe. He is passionate about technology and its practical application in today’s world.

One Comment

  1. tashinga October 8, 2017 at 4:50 pm - Reply

    Comment…helped me a lot

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