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Fire blight
Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard in a single growing season.
The causal pathogen is Erwinia amylovora, a Gram-negative bacterium in the genus Erwinia, order Enterobacterales. It is a short rod with rounded ends and many peritrichous flagellae. Pears are the most susceptible, but apples, loquat, crabapples, quinces, hawthorn, cotoneaster, Pyracantha, raspberry and some other rosaceous plants are also vulnerable. The disease is believed to be indigenous to North America, from where it spread to most of the rest of the world.
Fire blight is not believed to be present in Australia though it might possibly exist there. It has been a major reason for a long-standing embargo on the importation of New Zealand apples to Australia. In Europe it is listed as a quarantine disease, and has been spreading along hawthorn (Crataegus) hedges planted alongside railways, motorways and main roads.
Experiments in the early 1800s demonstrated that E. amylovora caused disease in plants, the first time that this could be shown. E. amylovora was found by Fritz Klement, a German scientist in 1910.[citation needed][clarification needed] It is generally accepted[by whom?] that this destructive crop bacterium initially originated in North America. Today, E. amylovora can currently be found in all the provinces of Canada, as well as in some parts of the United States of America, including Alabama, California, Colorado, Connecticut, Georgia, Illinois, Maine, Maryland, Massachusetts, Michigan, New York, North Carolina, Ohio, Oregon, Pennsylvania, Texas, Utah, Virginia, Washington, West Virginia and Wisconsin. In the Americas it also occurs in other countries including, but not limited to, Mexico and Bermuda. On the African continent, E. amylovora has been confirmed in Egypt.[citation needed]
It is believed that the pathogen was first introduced into Northern Europe in the 1950s through fruit containers, contaminated with bacterial ooze, imported from the USA. During the 1950s-1960s, E. amylovora spread through much of Northern Europe. Initially large areas of Germany and France seemed untouched by fireblight, but the disease, and E. amylovora, were discovered in the later 1990s in Germany. In the 1980s the bacterium was found in isolated regions in the Eastern Mediterranean and from the years 1995-1996 cases of fireblight began to be reported in countries such as Hungary, Romania, Northern Italy and Northern Spain.[citation needed]
Erwinia amylovora overwinters in cankers formed during the previous season. In the spring warmer temperatures support development and bacteria-filled ooze begins to exude from the cankers. The factors that determine whether or not cankers become active are not well known, but it is thought that cankers found on larger or older tree limbs are more likely to become active. Honeybees and other insects are attracted to this ooze and can spread bacteria to susceptible tissue, such as flower stigmata. Birds, rain and wind can also transmit the bacterium to susceptible tissue, the colonisation of which will be heavily decided by temperature (21-27 C is most favourable) and moisture either from rain or heavy dew. Bacterial procession into the nectaries – cause "blossom blight". Flowers one to three days old are more susceptible than those five to eight days old. See Curry 1987 for the source and further review of this subject.
Other than through the flowers, the bacterium can enter the plant through the stomata. Also highly susceptible to infection are lesions such as punctures caused by plant-sucking insects and tears caused by a variety of means, including infected cultivating tools. A few minutes of heavy hail can spread the disease throughout an entire orchard and growers normally do not wait until symptoms appear but begin control measures[citation needed] within a few hours.[citation needed]
Once the bacterium gains access to the xylem or cortical parenchyma of the plant, it causes blackened, necrotic lesions, which may also produce a viscous exudate. This bacteria-laden exudate can be distributed to other parts of the same plant or to susceptible areas of different plants by rain, birds or insects, causing secondary infections. The disease spreads most quickly during hot, wet weather and is dormant in the winter when temperatures drop.[citation needed]
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Fire blight AI simulator
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Fire blight
Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard in a single growing season.
The causal pathogen is Erwinia amylovora, a Gram-negative bacterium in the genus Erwinia, order Enterobacterales. It is a short rod with rounded ends and many peritrichous flagellae. Pears are the most susceptible, but apples, loquat, crabapples, quinces, hawthorn, cotoneaster, Pyracantha, raspberry and some other rosaceous plants are also vulnerable. The disease is believed to be indigenous to North America, from where it spread to most of the rest of the world.
Fire blight is not believed to be present in Australia though it might possibly exist there. It has been a major reason for a long-standing embargo on the importation of New Zealand apples to Australia. In Europe it is listed as a quarantine disease, and has been spreading along hawthorn (Crataegus) hedges planted alongside railways, motorways and main roads.
Experiments in the early 1800s demonstrated that E. amylovora caused disease in plants, the first time that this could be shown. E. amylovora was found by Fritz Klement, a German scientist in 1910.[citation needed][clarification needed] It is generally accepted[by whom?] that this destructive crop bacterium initially originated in North America. Today, E. amylovora can currently be found in all the provinces of Canada, as well as in some parts of the United States of America, including Alabama, California, Colorado, Connecticut, Georgia, Illinois, Maine, Maryland, Massachusetts, Michigan, New York, North Carolina, Ohio, Oregon, Pennsylvania, Texas, Utah, Virginia, Washington, West Virginia and Wisconsin. In the Americas it also occurs in other countries including, but not limited to, Mexico and Bermuda. On the African continent, E. amylovora has been confirmed in Egypt.[citation needed]
It is believed that the pathogen was first introduced into Northern Europe in the 1950s through fruit containers, contaminated with bacterial ooze, imported from the USA. During the 1950s-1960s, E. amylovora spread through much of Northern Europe. Initially large areas of Germany and France seemed untouched by fireblight, but the disease, and E. amylovora, were discovered in the later 1990s in Germany. In the 1980s the bacterium was found in isolated regions in the Eastern Mediterranean and from the years 1995-1996 cases of fireblight began to be reported in countries such as Hungary, Romania, Northern Italy and Northern Spain.[citation needed]
Erwinia amylovora overwinters in cankers formed during the previous season. In the spring warmer temperatures support development and bacteria-filled ooze begins to exude from the cankers. The factors that determine whether or not cankers become active are not well known, but it is thought that cankers found on larger or older tree limbs are more likely to become active. Honeybees and other insects are attracted to this ooze and can spread bacteria to susceptible tissue, such as flower stigmata. Birds, rain and wind can also transmit the bacterium to susceptible tissue, the colonisation of which will be heavily decided by temperature (21-27 C is most favourable) and moisture either from rain or heavy dew. Bacterial procession into the nectaries – cause "blossom blight". Flowers one to three days old are more susceptible than those five to eight days old. See Curry 1987 for the source and further review of this subject.
Other than through the flowers, the bacterium can enter the plant through the stomata. Also highly susceptible to infection are lesions such as punctures caused by plant-sucking insects and tears caused by a variety of means, including infected cultivating tools. A few minutes of heavy hail can spread the disease throughout an entire orchard and growers normally do not wait until symptoms appear but begin control measures[citation needed] within a few hours.[citation needed]
Once the bacterium gains access to the xylem or cortical parenchyma of the plant, it causes blackened, necrotic lesions, which may also produce a viscous exudate. This bacteria-laden exudate can be distributed to other parts of the same plant or to susceptible areas of different plants by rain, birds or insects, causing secondary infections. The disease spreads most quickly during hot, wet weather and is dormant in the winter when temperatures drop.[citation needed]