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, flowers and roots

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

Is it Vine Weevil?

Adult Vine Weevils are black beetles about 8mm long narrower at the front than the back.  If you see bitten edges around the leaves of your plants, then suspect vine weevil. They are rarely seen in the daytime.  The larvae are grubs which feast on plant roots, often completely severing them from the upper stems. They have a soft creamy-white body, up to 1.5 cm long and brown heads. They mostly lie in a sort of "C" shape.  The damage caused by the adults is unsightly but the grubs can cause the plant to die.  More...

Is it slugs?

Slugs eat leaves, stems and roots of plants, weakening them and often causing them to die.  They leave slimy trails over plants and soil, and are particularly devastating to seedlings and cuttings. Slugs leave their own individual scent trails so they can find their way home. There are other creatures (like caterpillars) who make big holes in leaves, but if you see the tell-tale slime, then slugs are the culprit!  More...

Is it Spider Mite?

Spider mites are best spotted by looking for plant damage. They pierce the leaf cells with their mouthparts and suck the plant juices.  The leaf damage initially results in a fine speckling effect on leaves where the cells have died. The pattern of the mottling varies from plant to plant.  When the infestation becomes advanced, fine webbing appears on new growth. The webbing acts to shield the colony and provide a series of ladders/netting which allow the mites to crawl from stem to stem.  Where webbing is widespread the leaves will typically turn brown and drop off due to the extent of the cell damage.  More...

Is it Thrips?

Thrips are best spotted by looking for plant damage as the pest itself is very small and difficult to spot. They feed on the plant's sap, causing the flowers, fruit and foliage to be deformed, weakening the plant and eventually killing it.  You will see the leaf surface turning a silver colour spotted with black spots indicating cell death.  Flowers may seem deformed with brown petals that may have ragged edges.  More...

Is it Whitefly?

This very active pest targets a wide variety of plants including brassicas and tomato plants in greenhouses and many popular houseplants.  They can be active all year round and, left uncontrolled, can quickly overwhelm a plant.  They are easy to spot, they lay their eggs on the underside of leaves, the adults are ghostly white and nearly always moving, unless they are settled on the underside of leaves.  More...

Is it Aphids?

Aphids are soft bodied insects which live on the sap of a wide number of plants. You will find them on the underside of leaves, and also clustering around buds and flowers. Aphids are generally greenish but can also be black, yellow, or pink. The green aphids typically found on roses are usually called greenfly, and the fat black aphids often found on broad beans are called blackfly.  More...

Is it Mealybug?

Mealybugs are little white-grey creatures which look a bit like tiny elongated woodlice.  They have a white waxy coating making it difficult to kill them with chemical pesticides. You will probably first notice you have a problem when the plants become festooned with clumps of white woolly egg masses. The real damage however comes from the bugs themselves, which suck fluids from the plant causing general weakness. Mealybugs are normally found on indoor plants such as cacti, succulents, citrus, orchids and tomatoes. They thrive in these warm conditions and are therefore active all year round.  More...