What's your plant problem?

Before you look for treatments, you really need to find what the problem is. This page suggests a logical approach to hunting down the enemy...

It may be worth starting right at the beginning - by examining the symptoms. If your plants look sickly it could be caused by:

  • 1. Shortage of food or water
  • 2. Disease (bacteria or virus attack)
  • 3. Attack by mould or fungus
  • 4 Larger birds or mammals eating the plants
  • 5. Something eating the roots
  • 6. Something eating the stem, leaves or flowers

Biological Controls will only help you with problems 5 and 6. So you need to actively look for, and be able to identify, a pest attack before you just assume that a sickly plant needs treatment.

Visible damage to stem, leaves and flowers

If the visible part of the plants are attacked then it is often possible to identify your pest by looking carefully at the damage.

Vine Weevil Damage Vine Weevil Bite-shaped damage round the edges of shrub leaves, making a scalloped pattern.  Symptoms of an insect with large strong cutting mouth parts which is chewing up the leaves from the edges inwards

Slug damage to leaves Slugs 
Irregular holes in the middle of leaves, and at edges. Often a tell-tale slime trail

Caterpillar damage Caterpillar
Irregular holes in the middle of leaves, with some at edges. Leaves between main ribs slowly and progressively eaten until skeleton remains

Spider mite damageSpider Mite
Pattern on leaves (in worst cases there is fine webbing between leaves). The damaged areas may be cream, white, or rust coloured.

Thrip Adults DamageThrip Adults
Tiny patches of damage on leaves - stripes and blotches on flowers caused by the juices being sucked from the leaves.

Thrips Larvae Damage

Thrips Larvae
Distorted leaf outlines - typically found on capsicums.  Caused by chewing the young tissue - when leaves or buds expand they may become distorted or torn, forming holes in the tissue.

Whitefly damageWhitefly
Yellowing leaves followed by black mold.  

They suck fluids from the plant and they deposit fluffy cotton-wool like egg masses in cracks and crevices on and around the plants.


Root Damage

Many flying insects have young which feed underground. Whether or not you can find root damage, you should be looking for any "grubs" that could be fattening themselves on the underground parts of your plant. Even if they are dormant because they are hibernating, they will wake up in spring and start feeding. Not all things that look like "grubs" are actually bad news - some of them eat other creatures rather than eating plant material. And some creatures are just sheltering underground in one of the stages of their life cycle.

Vine Weevil GrubVine Weevil Grub
You can recognise them by their soft creamy-white body, up to 1.5 cm (half inch) long and their brown heads. They often lie in a sort of "C" shape.

Sciarid Fly LarvaeSciarid Fly Larvae
The small white larvae live in the compost and feed on the tender roots of plants and cuttings. Tiny, tiny threadworms almost invisible to the naked eye.

Chafer GrubsChafer Grubs
White grubs with a brown head, not unlike Vine Weevil grubs but bigger and shinier with distinct pairs of legs at the front end.

Larvae of the crane fly long, greyish segmented body, about 2.5cm (1 inch) long, legless and with no distinct head.