General Garden Pests

General Garden Pests

Ants

Ants can be disruptive but they rarely cause any serious or direct damage to plants.

Typical symptoms: Plants in pots and bare ground grow poorly where ants have tunnelled underneath; heaps of dry soil appear in lawns where ants are present. Aphid problems are exacerbated when ants move them to different feeding sites around a plant and defend them from predators.

General Garden Pests Prevention and treatment: Little can be done to banish ants from the garden, although it is possible to protect individual trees and pots with grease bands as used for codling-moth control. Pots and greenhouse staging, popular refuges for these insects, can also be protected with a non-drying glue; regularly check that these barriers have not been breached.


Birds

Birds are generally welcome in the garden for their decorative and harmonious qualities, but some can cause severe damage to fruit, flowers and vegetables.

Typical symptoms: Fruit buds are eaten; holes are pecked in pea pods; leaves of brassicas are pecked and torn; crocus petals are torn; and fruit is eaten.

Prevention and treatment: Cover plants with net or Scaraweb or grow them in a cage. Where birds are not such a problem, try various scaring devices, changing the type every so often as soon as the birds soon get used to the different methods.


Earwigs (Forficula auricularia)

These creatures are useful pest controllers, but they can also damage fruit, seedlings and some flowers.

Typical symptoms: Ragged holes in the petals of chrysanthemums, dahlias and other ornamental flowers and also in young leaves and buds. Earwigs are often found nestling in cavities in fruit but the insects themselves rarely initiate such damage.

Prevention and treatment: tidy up unnecessary debris where earwigs could breed and hide. Earwigs tend to congregate under materials such as planks of wood or sheets of cardboard laid on the soil or in straw-filled flower pots on top of a cane. They can then be collected up and disposed of.


Leatherjackets (Tiplua spp.)

Leatherjackets are fat, greyish-brown larvae up to 5cm (2in) long. The juvenile form of the crane fly, they feed on plant roots and are mainly a pest of lawns, where they create yellow patches, especially during dry weather. The activity of starlings and other birds searching for leather-jackets can further damage the lawn; young plants growing in newly turned grassland are also at risk.

Typical symptoms: Plants turn yellow, wilt and die; yellow patches appear in lawns.

Prevention and treatment: First confirm the presence of leatherjackets, as these symptoms can have other causes. Regular cultivation and weed control should gradually clear these pests from plots and borders. On lawns, water the grass well, then cover it with thick cardboard or plastic overnight. This will bring the leatherjackets to the surface, from where they can be collected. On cultivated land, trap them by covering well-watered ground with lawn mowings, topped with cardboard or plastic. Leave for several days before collecting up the pests and disposing of them.


Millipedes (Blaniulus guttulatus and others)

These slow-moving, many-legged creatures feed mainly on dead plants or they extend wounds caused by other creatures in roots, tubers, corms and bulbs.

Typical symptoms: Seedlings, especially of peas and beans, germinate poorly and pieces are eaten away.

Prevention and treatment: Encourage their natural enemies, which include birds, hedgehogs and ground beetles. Cultivate land regularly to disturb the millipedes and expose them to predators.


Moles (Talpa europaea)

The activities of these beautiful and hard-working creatures — tunnelling and the production of molehills — undermine and disturb plants.

Typical symptoms: Plants wilt or grow poorly for no apparent reason. Tunnels are found under plants; mounds of soil appear in beds and lawns.

Prevention and treatment: Many gadgets making a sound or vibration in the soil are said to repel moles but they rarely have any effect. Trapping, carried out by an expert, is really the only effective answer.


Rabbits (Oryctolaqus cuniculus)

These creatures can cause severe damage to a wide variety of fruit, vegetables and ornamental plants.

Typical symptoms: Many plants are grazed; young shoots and leaves are eaten; bark is often stripped away from young trees. Rabbit droppings are visible.

Prevention and treatment: Trunks of individual trees and shrubs can be protected with spiral tree guards. Tree shelters, used for young trees, will also keep rabbits at bay. Fencing is the most practical way of protecting a garden. Use wire mesh netting, maximum mesh size 5cm (2in), approximately 1m (31/2 ft) high. The bottom 15cm (6in) should be bent out at an angle of 90° so that it lies flat on the ground, pointing away from the garden. Bend the top 15cm (6in) out at an angle of 45° to prevent the rabbits from climbing over. A simpler though more costly alternative is to use an electric fence, and there are special designs available specifically for rabbit control.


Scale insects (Coccus hesperidium and others)

These small, limpet-like creatures are widespread pests of ornamental plants, especially in greenhouses.

Typical symptoms: Sticky honeydew is produced on which black moulds grow. A severe infestation can weaken growth and make the plant look unsightly.

Prevention and treatment: Always examine new plants for scales before introducing them into the garden or greenhouse because this is the main way in which scales are spread. Where scales are present, and the leaves of the plant are tough enough, gently rub the creatures off the plant using a soft cloth or toothbrush and insecticidal soap. Try a test run on an individual leaf first if you are unsure if the plant will take this kind of treatment. The only effective time to spray this pest is when the juvenile scales, tiny mobile creatures known as “crawlers”, are present. Outdoors, this is usually during late spring to early summer, but indoors, it can be almost any time of the year. To do this, use a magnifying glass to help identify the presence of crawlers and then spray affected areas with insecticidal soap.


Vine weevil (Otiorhynchus sulcatus)

The vine weevil larvae are serious pests that can affect a wide variety of plants, especially those grown in containers. The adults do some damage, but this is generally much less serious.

Typical symptoms: Plants wilt suddenly and, if watered, do not recover. This is because the roots have been eaten away by the larvae. Plump, creamy-white, brown-headed larvae, up to about 1cm (1/2in) long, are found in the soil around the plant. The adult vine weevil feeds at night, making irregular holes and notches in plant foliage.

Prevention and treatment: Check the compost of new plants for the presence of vine weevil larvae; destroy any that are found. As the adult vine weevil cannot fly, individual pots and greenhouse staging can be protected with a band of non-drying glue. If a wilting plant is caught in time, it can be potted up into clean soil and may recover.

A biological control agent, the parasitic nematode Heterorhabditis megidis, can be used against this pest.


Wireworm (Agriotes spp.)

These slender, shiny brown, tough beetle larvae live in the soil and feed on the stems, tubers and roots of many plants. They are a particular problem on newly broken ground.

Typical symptoms: Plants may not thrive; knitting needle-type holes can be seen in tubers.

Prevention and treatment: Thorough cultivation and weed control should reduce the problem in newly cultivated ground. Lift potatoes by early autumn to limit damage. In small areas, such as a greenhouse, trap wireworm in pieces of potato or carrot spiked on a stick and remove them regularly.

31. January 2011 by Dave Pinkney
Categories: Organic Gardening, Pests and Diseases, Plant Care | Tags: | Comments Off on General Garden Pests

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