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The Scharkakrankheit is a plant disease, which is due to the so-called Scharka virus and affects mainly various stone fruit trees - plum or nectarine trees are particularly affected here. The plant disease can also be found, for example, in various weeds.
A direct control of the virally-related disease in terms of the healing of infected plants is currently not possible - therefore achieve various control measures primarily the avoidance of disease transmission to previously healthy population.
Early detection of plant diseaseIt is important to know the symptoms of plant disease so that the Scharkakrankheit can be quickly discovered on their own plant life and thus can prevent their spread. In stone fruit trees, the virus infection is mainly due to the fruits. Corresponding first fruit symptoms are already manifesting from the middle of July before maturation of the fruit - mention may be made here, for example, depressions in the skin, which may be belt or ring-shaped. Also appearing malformations of the fruit can speak for the Scharkakrankheit. The plant disease then becomes clear primarily through the view of the interior of affected stone fruit - on the stone are usually strong pale drawings in ring form. Characteristic is also a red-brown pulp of rubbery consistency. Affected fruits usually show decreasing palatability and reduced sugar content.
In addition, even less clearly recognizable leaf symptoms may indicate a viral plant infestation. As early as June, the leaves of stone fruit trees show spots or rings in olive tint. However, these leaf symptoms do not occur every year.
In order to prevent an uncontrolled spread of the Scharkakrankheit, the virus infestation according to the German Federal Code (BGB) is subject to a reporting obligation. If, for example, trees are affected by the plant disease that is less than three years old at its current location, the origin of the relevant plants must also be stated. If mandated by a local authority, even breeding and / or distribution of plants may be subject to mandatory reporting, which is particularly vulnerable to the Scharka virus.
Destruction of infested plants
Following notification of plant stocks infected with the Scharka virus, the competent authority may request the destruction of affected plants. Corresponding disposal must then be carried out by means of excavation and incineration - as a rule, these measures must take place at the direct location of diseased plants or in the immediate vicinity. If incineration of the plants to be disposed of can only take place through a previous transport of the latter, it is the duty of the law to destroy insects (such as aphids) which are found on the infected stock and which are considered as transmitters of the virus. Caution is also required in dealing with used documents.
If there are cases of Scharka's disease on a particular plot or if the suspected viral plant disease is suspected, the competent authority may impose a ban on cultivation on the basis of the Federal Act on Adjacent Areas. Such a prohibition of up to 12 months applies to plants known to be susceptible to infection by the Scharka virus.
If plants are grown in an area with known occurrences of the Scharkakrankheit, which can in principle suffer a corresponding viral infection, it is advisable to select varieties with relatively high resistance. In contrast to so-called susceptible plant varieties, the fruit of which is usually not marketable in the present infection, symptoms are less pronounced in tolerant varieties - corresponding stone fruit is usually edible.
For example, in order to prevent the onset of shark disease, research has focused on the development of stone fruit varieties that are completely immune to the disease of the shark. The first fully resistant variety of plum could be bred as early as the 1980s.
Disease control measures:
- early symptom detection & notification
- Destruction of infested plants
- local insect control
- alternative cultivation of tolerant / resistant varieties
Affected plants: apricot, peach, but especially plum and plum.
Damage: fruits fall off before maturity. Other symptoms are highly varietal. In plums the fruits are criss-crossed by wide, deep cracks, the pulp is rubbery and brown. Leaves with faded ring or band-shaped spots. Apricot and peach fruits with brown spots and rings. The Scharkakrankheit is transmitted by hostile aphids and, like all diseases caused by viruses can not be combated.
Most dangerous time: entire growing season
Defense: Diseased trees must be cleared and destroyed.