Common Plant Pests

Pests

Plants affected: Normally a greenhouse pest, does enjoy fuchsias and tomatoes

Symptoms: Clouds of tiny white triangular moths are found on the underside of leaves. Black sooty mould may also be seen on the leaves

Control: Resistant to most pesticides, best to use organics methods such as biological control or yellow sticky traps. Bright yellow plants could be planted with other vulnerable, but less valuable plants which can act as a decoy

Blackfly

Plants affected: Broad bean shoots, elder bushes, dahlia flower stems

Symptoms: large black greenfly cluster round the tips of shoots

Control: Nip the tip of shoots out as soon as you notice this infestation, spray with a soft soap or a pesticide that contains pirimicarb

Greenfly

Plants affected: All sorts

Symptoms: Infestations of green, pink, cream and brown insects around the softest part of the plant, new growth tips and young tender leaves.

Control: Pinch off using your fingertips, spray with a soft soap, or use a pesitcide with pirimicarb

Scale Insects

Plants affected: Green house plants, especially ones with really thick, waxy evergreen leaves

Symptoms: Tiny limpets cling to the stems or undersides of leaves

Control: Wipe off with cotton buds and methylated spirit, then wash the leaf with tepid water and remove the sooty mould

Red Spider Mite

Plants affected: Mainly greenhouse or indoor pot plants.

Symptoms: Pale buff coloured speckles on the leaves. A bad infestation will be indicated by fine webs around shoots and on young leaves

Control: Very difficult even with chemicals. If greenhouse plants are effected, spray down the area to create a damp atmosphere which the spider mite will not thrive in. Or use plant oils or fatty acids on edibles or an insecticide containing bifenthrin on ornamentals.

Vine Weevil

Plants affected: shrubs, small trees, and some house plants

Symptoms: Semi circle shaped notches along the margins of leaves caused by the female adults. No male adults are known to exsist. The larvae feed on the roots of the plants. These are cream coloured grubs, about .5cm long with a brown mouth part. Most plant damage is caused by this grub, as they will feed on the plant's root system, eventually killing the plant.

Control: If you want yo use a chemical it needs to contain the ingredient thiacloprid. An organic method would be to remove and destroy newly pupated adults to reduce the number of egg laying adults, use netting and fleeces to prevent the flightless adults from moving, or use commercially available nematodes such as heterorhabditis that can be watered into the soil to control vine weevil larvae

Mealy Bug

Plants affected: Infest greenhouse or house plants, some outdoor plants such as phormiums. Mealy bugs feed on leaf sap, which they suck through a tubular mouth part.

Symptoms: Wilted, stunted and dehydrated plants that may be loosing their leaves. The foilage normally becomes sticky with honeydew that can harbour dark sooty mould. You will be able to spot the mealy bugs at the base of the plant.

Control: Remove any leaves or shoots that are affected by the bugs, or a chemicals such as natural fatty acids or a chemical containing surefactant based products

Slugs and Snails

Plants affected: they feed on a wide range of plants eating any part

Symptoms: They leave a silvery slime trail and eat young plant parts, the leaves and flower buds, they tend to hide under foliage and in dark, damp crevices.

Control: Use copper rings around the perimeter of susceptible plants, a sharp textured mulch such as crushed egg shells can help. Slugs and snails are attracted to beer, so place beer traps near to target plants. If you want to use a chemical select one which contains copper sulphate, aluminium sulphate or metaldehyde

Wooly Aphids

Plants affected: Apples, cotoneaster, hawthorn, pyracantha and sorbus

Symptoms: Fluffy white, waxy aphids cause swellings on branches, if the swellings spilt open in winter, infections can set in and cause canker

Control: Blast off the fluffy sticky aphids with a high speed jet of water, this won't cure the problem long term. Can spray with chemicals that contain bifenthrin or thiacloprid the moment you spot any aphids, small numbers are easier tackled than letting them multiply

Aphids

Plants affected : Most plants attract aphids

Symptoms: There are many different aphids, but they all tend to attack young sappy growth first, Early indications are that leaves curl up, growth becomes stunted and the plant weakens and, in severe, untreated cases, can die. They starve the plant by covering the leaves with a sticky residue which attracts sooty moulds. The leaf cannot photosynthesise and becomes starved of energy.

Control: You can use soap sprays, but for this to work it must come into contact with the pests. Or use a chemical which contains Bifenthrin and again, spray directly onto the pest

Whitefly