Plant pests and diseases Pests Sucking pests Sucking

Plant pests and diseases

Pests Sucking pests • Sucking pests place stylets into leaves, stems or roots and suck the sugary sap • When the stylet is removed the liquid often continues to pump out • This attracts sooty mould ants

Aphids

Scale insects Chinese scale Waxy scale

Chewing insects • Often only stages in part of the life cycle of the insects damages plants • This stage is often the caterpillar which does not fly and is therefore easier to control • The adult is more mobile and lays the eggs which turn into the caterpillar

How chewing pests effect plant growth • Chewing pests make holes in leaves and stems • This gives the leaves less area to absorb light and photosynthesise. Giving the plants less food to grow • The stems may not be able to transport water and nutrients up to the leaves or food around the plant

Chewing insects – Caterpillars

Thrips

Rasping pests • The tongues of these animals have small teeth which act like sandpaper making holes in leaves

Controlling pests • Biological control uses one organism to control another • E. g ladybirds eat aphids

Using sprays • “Soft” sprays, like Bt which attacks a caterpillar’s gut, but do not harm the environment are used in the “Kiwigreen” initiative • Inorganic sprays e. g. Carbaryl are toxic to insects and the rest of the environment and are only used when nothing else will control the insects

Monitoring • Insects are attracted to the colour yellow • A yellow plastic sheet is coated with oil and the insects fly to it and get stuck • The numbers and varieties can be analysed and course of action decided