The severity of disease is dependant on cultivar and rootstock susceptibility, general tree health, cultural practices and environmental conditions. In severe cases, when the bacteria progresses into the trunk or infects the rootstock, entire trees can be killed. The disease can result in the loss of branches and tree structure. The parts you cut off should be burned promptly.Fire blight, caused by Erwinia amylovora, is a bacterial disease of apple, pear, hawthorn, crabapple and ornamentals in the Rosaceae family. Do this in dry weather and sterilise the secateurs or saw between cuts with household disinfectant or bleach. Branches under 25mm in diameter should be cut at least 30cm below the last trace of red staining, and with larger branches this should be 60cm. The disease cannot be cured but, if caught early, the spread of infection on larger trees can be halted by pruning out affected branches. Q How do I treat trees affected by fireblight?Ī Young trees and shrubs are best removed entirely. Early-flowering apple and pear varieties tend to be less prone. 'Professor Sprenger' and ornamental pear Pyrus calleryana 'Bradford' are very resistant. The ornamental crab apples Malus 'Liset', M. The Swedish whitebeam Sorbus intermedia is thought to be immune. If you live in Northern Ireland, the Isle of Man or the Channel Islands and suspect an outbreak, even in a garden, then you must also report it.Ī If it is a problem in your area you should avoid planting susceptible shrubs, and hawthorn. This attempt was abandoned in 1993 – partly because it is impractical to control the disease in hawthorn hedges. At first, the authorities attempted to control the disease's spread, and had to be informed of any outbreaks. Fireblight originated in the USA and was first recorded in the UK in 1957, in a pear orchard in Kent. It is uncommon in the most northern counties of England and Scotland and it is absent from Northern Ireland, the Isle of Man and the Channel Islands.Ī In some circumstances, yes. In larger trees, the disease may naturally peter out after a couple of years.Ī The disease is widespread in most of England and Wales. The infection spreads quickly down the shoot to larger branches and may kill a young tree or shrub in a single season. Infection commonly occurs through flowers during pollination, but can also enter via pruning wounds or leaves damaged by weather or insects. They can then be spread by insects, rain, wind, birds or gardeners. In spring they multiply and ooze out in droplets. Blossom wilt, spur blight and wither tip caused by the brown-rot fungus also kill shoot tips, but do not spread far down the branches or produce cankers or red-brown staining on the branches.Ī The bacteria overwinter on the bark round the edges of cankers. Fungal cankers tend to be dry, and there is no red-brown staining below the bark. Q Can I confuse fireblight with anything else?Ī On apple and pear trees, fungal canker can kill shoot tips, and it is more common than fireblight. Late-flowering fruit varieties are more vulnerable because flowering occurs at higher temperatures. Plums and other prunus species are not affected.Ĭaption: Amelanchier is one of the plants that can be affected by fireblightĪ It generally develops at flowering time, and is encouraged by warm, wet weather. This includes amelanchier, apple, cotoneaster, flowering quince (chaenomeles), hawthorn, rowan, pear, pyracantha, quince and whitebeam. Drops of whitish or yellowish bacterial pus may seep out from dead tissues in spring and summer.Ī Fireblight only affects the sub-group of plants with apple-like fruits (maloideae) within the large rose family (rosaceae). Q What further checks can I make to confirm it's fireblight?Ī Below the damaged bark, the cambium layer, which is usually creamy white, develops reddish-brown staining. Cankers develop at the base of affected shoots. Bark in affected areas dies, and may appear dark, sunken or cracked. Twigs, large branches or whole trees may die. The dead leaves and flowers slowly disintegrate and fall over a long period. Affected shoots are usually scattered throughout the canopy and may appear next to perfectly healthy ones. The shrivelled shoots tend to have hooked tips, like a shepherd's crook. The name comes from the characteristic blackening of affected leaves and shoots.Ĭaption: Fireblight causes flowers and/or shoot tips to wilt and dieĪ Flowers and/or shoot tips wilt and turn brown or black. A A serious and potentially fatal disease of pears, apples and related plants caused by the bacterium Erwinia amylovora.
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