![]() Short animated disease fact sheet: ‘Fire blight A Bacterial Disease of Apples and Pear’. Use antibiotics and biocontrol during high risk periods in combination with disease forecasting models.Prune infected plant parts and dispose of appropriately.Use clean plant material for grafting and rootstocks.Plant resistant scion varieties and rootstocks.How do I prevent and control fire blight? Alternative hosts of the fire blight bacteria are many other plants from the Rose family, including serviceberry ( Amelanchier spp.), cotoneasters ( Cotoneaster spp.), hawthorn ( Crataegus spp.), quince ( Cydonia spp.), blackberries ( Rubus spp.), raspberries ( Rubus spp.), and mountain ashes ( Sorbus spp.). Where does fire blight come from?īacteria overwinters in old cankers and in early spring insects, bees and farm management tools, rain splashes move it to natural openings of the plant or injured parts. The visual symptoms may slightly vary depending on weather conditions and plant variety. The inner bark of the infected stem turns from green to brown. Fire blight cankers on stems appear as slightly sunken, dark discolored areas with a narrow callus ridge. Infected twigs and young branches darken and their tips usually bend to form a “ shepherd’s crook.” During warm and moist conditions, infected tissue may exude bacterial ooze in droplets. Infected leaves wilt, darken, and remain attached to the tree. Infected blossoms appear water-soaked, wilt, turn dark brown and remain attached to the tree. The name “fire blight” comes from the fire-scorched appearance of infected organs. Blossoms, shoots, and rootstock infections are called ‘blossom blight’, ‘ shoot blight’, and ‘ rootstock blight‘, respectively. The disease cannot be cured but, if caught early, the spread of infection on larger trees can be halted by pruning out affected branches. The bacteria can enter into the host plant from natural flower openings or injuries due to rain, hail storm, insect damage, or farm machinery. In South Carolina, the recommended crabapple varieties that are resistant to many common diseases include ‘Adams, ‘ ‘Mary Potter,’ ‘Professor Sprenger,’ ‘Red Baron’ and ‘Indian Magic.’. It is caused by a gram negative bacteria called “ Erwinia amylovora“. High resistance to scab, resistant to cedar apple rust, and somewhat resistant to powdery mildew and fire blight. Fire blight is the most devastating bacterial disease of apples, pears and crabapples.
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