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Fire blight is a disease that affects mainly pome fruit plants (for example, apple and pear trees, cotoneaster, red, white and firethorn and quince). Berry and stone fruits as well as coniferous and deciduous trees are not affected by fire blight. The disease is caused by the bacterium Erwinia amylovora and can spread very rapidly. Although fire blight is very dangerous for fruit growing, there is no danger to human health.
- Fire blaze detect: wilting, non-deciduous leaves
- Pathogen: Erwinia amylovora
- Routes of infection: contaminated plant material or objects, spread by weather or living things
- Disease: wilting flowers and leaves, discolored brown or black
- Countermeasures: cut out infected parts of the plant and burn them
Withering leaves on the shoot tips are a typical symptom of the fire blight. These do not fall off, but remain hanging. The affected areas turn brown or even black and often look as if they have been burned. Every now and then the shoot tips can also be bent in a hook shape. Another typical feature of this disease is bacterial mucus droplets that occur in summer and autumn.
Fire blight is triggered by the pathogen Erwinia amylovora. This bacterium belongs to the family Enterobacteriaceae, is partially mobile and even viable in the absence of air. The bacterium can develop at temperatures between 3° C and 42° C. However, the optimal temperature for the growth of the pathogen is between 21° C and 28° C.
routes of infection
There are several ways in which fire blight is transmitted. Over long distances, infection may be caused due to contaminated plant material or objects. Even migratory birds can spread the pathogen over long distances. In the immediate vicinity of the spread of the bacterial mucus by rain, wind or insects takes place. Even birds, small mammals or humans themselves can spread the pathogen. During growth, the bacteria invade the plant. Here are 3 types of infection. The most common variant is the flower infection. Somewhat rarer is the Treibinfektion. Also again becoming active damaged areas are sometimes observed. In spring and summer, the risk of infection with fire blight is particularly high.
If a plant is infected with fire blight, withered leaves and flowers and turn brown or black. Affected areas look like burned, hence the name "fire blight". Frequently, the shoot tips are bent like a hook. Bacterial mucus appears at the infection sites. Young plants die within 2 to 3 weeks. In older plants, the disease is spread within a year or more and ultimately leads to death. For a clear diagnosis the examination of a laboratory is necessary. The severity of the attack depends on various factors. Depending on the location, climate and plant species, the infestation intensity may vary.
If there is a suspicion of an infection with fire blight, the plant protection department responsible for the respective place should be informed, because this illness can seriously threaten the fruit production. In order to avoid fire blight, one can fall back on resistant varieties already with the new planting. Among the apple varieties are Florina, Boskop, Bohnapfel, Pirella, Maunzen, Reanda, Landsberger Renette, Kaiser Wilhelm, Jakob Fischer and Glockenapfel as well as the pears Gute Luise, Diels Butterbirne and Alexander Lukas. The plants should be checked regularly for signs of fire. If an infestation is discovered, infested shoots must be cut back to healthy wood. For heavily infested plants we recommend clearing. To avoid further spread, infested plant parts should not be placed on the compost and used tools should be disinfected with alcohol. It is recommended that these parts of the plant be used for garbage disposal or at best burned.
- Affected plants: Woods of the family of the rose family, such as apple and pear and their ornamental forms, rowan, rock pear, hawthorn, red and hawthorn, quince, Stranvaesia, cotoneaster
- Damage: Flowers and peduncle stain in spring, in late flowering shrubs in summer initially brown, then black, but do not fall off. Young shoots curve in a hook shape. In summer to autumn, affected areas of the bark turn reddish to brown.
- Most dangerous time: spring to summer
- Defense: Affected woody plants, especially near fruit-growing areas, must be cleared and destroyed.