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 and 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