Pest & Disease Management Factsheets
Factsheets with detailed information on how to recognise and deal with the the most common plant pests and diseases.
These pathogens are characterised by sporulating on the under-surfaces of leaves with chlorotic and necrotic areas found on the upper surfaces, writes Geoffrey Dixon.
Plasmodiophora brassicae can be a problem for all brassica varieties, Professor Geoffrey Dixon warns.
Heavy infestations of these sap-sucking pests can kill plants but preventive measures can be taken.
Fungal leaf spots are probably the most common of all plant diseases and on deciduous trees may appear dramatic -- such as acer tar spot (see picture) - but do little long-term damage.
Bremia lactucae can be a major problem for field vegetable growers, Professor Geoffrey Dixon warns.
The risk of this fungal infection on sports and amenity turf can be lowered through careful management.
With their pear-shaped bodies, long antennae and a pair of rear-end siphunculi -- or exhaust pipes as they are sometimes described -- aphids are one of the most easily recognised and common glasshouse pests.
Whiteflies are sap-sucking insects that can be found in high numbers on protected crops. They can also attack outdoor crops including brassicas.
This disease kills seedlings by drawing on the nutrients of a host's dead cells, causing plants to collapse.
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Sooty moulds can take up levels of management time out of all proportion to the actual damage that they do to plants.
With action difficult and labour intensive, accurate identification of this root disease is key to tackling infection.
The glasshouse red spider mite, also known as the two-spotted spider mite, is a troublesome pest of both protected and outdoor ornamentals.
Ash dieback is caused primarily by the fungal disease Chalara fraxinea. The number of infected trees in Europe has risen over the past few years, partly due to wet summer weather.
Despite its limited impact on plant health, this fungal infection can cause customers to reject plants.
Foliage damage can render some plants unsellable.
The biting mouthparts of this large group of pests mean that all parts of the plant are at risk of attack.
Dutch elm disease is a fungal wilt spread by the elm bark beetles Scolytus scolytus and Scolytus multi-striatus.
Sudden oak death has caused extensive damage to a wide range of hosts on both sides of the Atlantic.
As well as attacking a wide range of crops, these pests can also carry major virus diseases.
The piercing and sucking mouthparts of these pests can lead to market rejections of ornamental crops.
The most common and damaging pathogen on ornamental lawns and sports turf in the UK is the fungus Microdochium nivale (syn. Fusarium nivale).
The animal's fast reproduction makes eradication impractical, but cooperative effort can limit crop damage.
This wood decay fungus can damage trees internally before any external evidence has been noticed.
Young shoots on plants are susceptible to grazing damage while bucks' antlers can harm bark.
This disease attacks woody plants in the Rosaceae family, which includes apples and pears, their ornamental equivalents plus others including amelanchier, aronia, Chaenomeles, cotoneaster, Crataegus, pyracantha and sorbus.
Beech bark disease is most likely to attack trees with trunks that are more than 20cm in diameter, although it can also be a problem on young plantations.
Feeding by slugs and snails is so economically damaging to farmers, growers and gardeners that millions of pounds have been devoted to finding new ways to combat these molluscan pests.
These larvae damage leaves on ornamental crops.
The genus includes a range of pests whose adults and larvae can do serious damage to ornamental plants.
The waxy scales of these pests can protect them from predators and insecticides and damage plant stock.
These two key groups can cause damage across a variety of ornamental crops.
Moles are widespread throughout Britain but absent from Ireland. Even small populations can damage sports turf, playing surfaces and amenity lawns, but control may not be necessary in less intensively used or managed areas.
Cankers in nursery stock species are characterised by the death of cambium tissue of woody stems, branches or twigs, causing them to sink in.
This pest can transmit a range of diseases.
Be alert to prevent damage from these pathogens.
Numerous conifer species are potentially at risk.
Black vine weevil (Otiorhynchus sulcatus) is a serious pest of ornamental nursery stock. The adults feed on susceptible plant foliage, leaving notched edges, and the larvae feed on roots.
Eelworms can carry viruses and cause damage by feeding on ornamental crops.
The threat to ornamental crops is on the increase.
Plants in poorly ventilated structures are vulnerable.
Poor husbandry, physical damage to roots and various diseases can all cause water deficit in leaves and non-woody stems of plants, leading to loss of turgor pressure in cells and flaccid tissues that we recognise as wilting.
Soil-dwelling larvae of chafer beetles and crane flies are serious turf pests, feeding unseen in the topsoil layer beneath lawns, golf courses and sports fields.
Pustules make this a relatively simple problem to identify but action must be taken to avoid damage.
Cyclamen, Poinsettia, Primula, Impatiens, Begonia, Nicotiana, Geranium and sweet peas are among 120 species in 15 families known to be susceptible to black root rot (Thielaviopsis basicola).
These easily-recognised glasshouse pests can wreak havoc with plants if they are not properly controlled.
A guide to identifying and treating this fungal disease, which can lead to defoliation and die-back.
Browntail and gypsy moth caterpillars can cause much damage to trees, but their risk to human health poses a bigger problem to local authorities.