Common Pests and Diseases


Landscape Designers & Gardeners	Beautiful Plants	Fun For Kids	Gardens in Context	Gift Ideas

Common Pests and Diseases

REGULAR MAINTENANCE

Most of the plants used in the garden are reasonably resistant to most pests and diseases. However, it is always possible that infestations can occur and diseases such as mildew and rust may attach some shrubs and herbaceous plants.

Aphids, Mildew, Rust, Black Spot etc. Often pest or disease attack may not be that severe or may be a short-lived phenomenon, in which case it is worth leaving well alone and allowing nature’s remedies to sort it out. This is particularly the case with an early attack of aphids, which usually soon passes.

However, if the attack is persistent or starts to adversely affect the plants then it needs to be attended to. There are many good all-purpose combination insecticide/fungicides, which will cover most problems in the garden. Most have the advantage of not harming bees or ladybirds. Doses should be repeated fortnightly until the attack has been eliminated. Certain pests and diseases are quick to form resistance to chemicals in the products. To prevent resistance building up it is advisable to alternate different brands that contain different chemical compositions.

Slugs and Snails may become troublesome especially around soft foliaged herbaceous plants. The best method of control is to set slug pellet baited pots on their side near the afflicted plant. This is a longer lasting method than just scattering them around & less hazardous to other wildlife. NB. Not all chewed leaves are caused by slugs and snails and it is worth checking that they are the cause: look out for telltale slime trails around or under the leaves.

Vine Weevil is a difficult to eradicate pest. Its symptoms are twofold. The adult form eats leaves of mainly evergreen plants e.g. Laurels, leaving a distinctive jagged edge.

The larvae cause much greater damage by invisibly attacking the root system of plants causing them to die, apparently quite suddenly. These can be seen as white grubs amongst the roots of affected plants.

The best treatment for vine weevils is a nematode that attacks the grubs and kills them. This must be applied according to manufacturer’s instructions at certain specified times of year.

Red Spider Mite shows as tiny red mites on the backs of leaves which have show distinctive tiny pale mottling all over the surface of the leaves. Bad infestations show webbing on affected plants. This is a pest that thrives in hot, dry weather. Affected plants can either be sprayed with appropriate insecticide or use a nematode.

Rosemary Beetle is a new pest that attacks Rosemary, Sage, Thyme, Lavender and other similar silver foliaged herbs. The beetle can easily be identified on affected plants: it is an attractive, bronzy purple, metallic beetle approx. half a centimetre long. There are grubs as well which will be seen feeding on the plants: these are more difficult to spot, being approx. half a centimetre long with greyish white mottled bodies. Destroy both adult and larvae squashing or similar. If severe infestations occur, treat with insecticide.

Nematodes for different pests can be viewed and purchased on the Internet at www.defenders.co.uk and many other suppliers.

Vine Weevil

Vine Weevil larvae

Vine Weevil leaf damage

Red Spider Mites

Rosemary Beetle