To prevent epidemics, there is a statutory requirement to report certain tree diseases and pests. Fire blight, Scharka and the San Jose Scale are notifiable in Germany, Austria and Switzerland.
Tree diseases are roughly divided into fungi, viruses, bacteria and diseases transmitted or caused by pests. Some of them pose enormous risks to the environment and require separate efforts to control them. Such diseases must be reported to the authorities. Contact here are the state offices or state institutes for agriculture.
Mandatory reporting does not apply to private allotment holders, but to professionals and certain occupational groups. Nevertheless, it is recommended that private individuals also report such pests and diseases. On the website of the Julius-Kuhn-Institute (JKI) there is an overview of all notifiable plant pests and diseases. "As an independent higher federal authority and federal research institute, today's Julius Kuhn-Institut is responsible as a departmental institution for all questions concerning the protection goal "crop" concern", states on the page of the institute.
In this article, we present three tree diseases or. -pests in more detail, which must be reported in Germany.
Tree aphids cause damage to crops but are not reportable in German-speaking countries. (Source: © nidan – Pixabay.com)
The fire blight
The bacterium "Erwinia amylovora" is the cause of one of the most dangerous diseases for apple, pear and quince trees, the so-called fire blight. Especially in the warm and humid weather of spring, the danger from the bacterium is imminent. It can penetrate into the wood via the blossoms. Clogs the power lines there. As a result, leaves are no longer supplied with water and nutrients, whereupon they turn blackish brown. The infested shoot bends. Eventually takes the form of a fire hook. Because the damaged area then looks like it has been burned off, the disease is called fire blight. Experienced fruit growers know that a possible
Epidemic often originates from red and hawthorn bushes and not from fruit trees.
In GDR times, for example, these bushes were "massively cleared," as an expert reports in the Thuringer Allgemeine newspaper. The slime of the bacterium is carried by wind, rain or insects and ultimately ends up on the trees. Incidents of fire blight have been reportable in Germany since 1985, according to the ordinance on fire blight control.
Countermeasures to fire blight:
In case of acute infestation, generously cut out the infested shoot; up to 30 centimeters into the healthy wood
If the infestation is established, either cut back the entire plant to the root or uproot the entire plant
After blending, disinfect the tools used with at least 70 percent alcohol
Burn prunings, if allowed by regional burn ordinance, or take covered to designated incinerator
Some fruit varieties are robust against fire blight. They are less susceptible, but can still become diseased. The Bavarian State Institute for Viticulture and Horticulture has posted an overview of fire blight-resistant apple and pear varieties online. If you plant one of these varieties, you have a lower risk of a possible infection. In Austria and Switzerland, by the way, there is an obligation to report the following
Suspected cases to fire blight.
The Scharka disease
Plums, plums, apricots, peaches, sloes and a number of ornamental shrubs from the genus Prunus can be infected by the Scharka virus. It triggers the eponymous disease in trees. In an online leaflet from the Thuringian State Institute for Agriculture, it says: "this disease is an economically very important pathogen."Although the leaflet is more than ten years old, it has lost none of its topicality. Even today, there is still no efficient pesticide that can be used to control the disease.
First reported to have been discovered in Eastern Europe as early as 1917. Now found almost throughout Europe. Mainly in May – but also from September – until the end of the vegetation period it spreads and infects the host plants. For laymen, Scharka disease is difficult to recognize, as the symptoms are very diverse and depend on the variety.
Several viral strains of the Scharka virus are also responsible for the many different forms of the disease. Known are a D-strain, M-strain, EA-strain, C-strain and recombinant strain. Symptoms on the leaves are light to yellow-green spots that appear mainly in spring. As the disease progresses, the spots can become black dots indicating dead tie.
The virus also attacks the fruiting bodies. They develop depressions caused by the disease, either pockmarked or linear on the fruit. The flesh of the fruit can turn red. Obtain a rubbery consistency. Ultimately, the fruit is inedible to humans. Carriers of the virus are aphids. They transport the disease from infected trees to healthy ones. However, humans have also contributed to the spread. In grafting fruit plants, conterminated shoots and rootstocks can spread the virus.
In Germany, the obligation to report is prescribed by the regulation for the control of Scharka disease. The virus cannot be controlled directly, but there are a number of measures to prevent its spread. In the following video clip (English) you can see the effects of the Scharka virus.
Countermeasures for Scharka disease:
Use only healthy planting material
Choose less susceptible and tolerant varieties when planting
Vector control in May/June and September
Immediately uproot and destroy diseased trees
There is currently only one known variety of plum that is resistant to the virus. The "yoyo plum" does not contract scharka. The Bavarian State Institute for Viticulture. Horticulture has posted an overview of hardy stone fruit varieties online.
The San Jose Scale
This pest from the insect family of the cap scale aphids attacks several fruit tree species and is therefore very feared. Apple, pear, cherry, plum, currant and citrus plants are among those at risk. That the plant is infected, you can tell by the damaged bark. This is covered with many round shields of wax, which can be colored from yellow-brown to black-gray.
Aphids live under this layer. Particularly heavily infested areas look as if they have been dusted with ash. The insects themselves appear like lemon-yellow, sac-like structures. Their larvae, on the other hand, can be identified as bright spots from June to October. This is precisely the period when the insects also attack leaves and fruit. Damaged fruit loses considerable quality. Can no longer be enjoyed. The louse is difficult to control chemically because of its shield. Mineral oil can be used effectively, however. The pests suffocate under the oil film. The insect can be treated biologically with the Prospaltella perniciosi wasp.
Countermeasures to the San Jose scale insect:
Spray mineral oil or rapeseed oil on affected areas
Have "Prospaltella perniciosi" wasp colonized, insects can be ordered from specialty stores
According to the Agricultural Industry Association, the San Jose scale insect appeared in the mid-20th century. In the early twentieth century in southern Germany on. Originally, this pest comes from the Asian region. If the insect is found, it must be reported to the competent authority.
Fire blight, Scharka and the San Jose Scale are notifiable in Germany. Allotment gardeners are exempt from the obligation. It is nevertheless advisable to report a possible occurrence. Here's how authorities can reduce the risk of an epidemic. To be sure if a tree is diseased or a pest has taken up residence, ask a tree expert. Damage like this can be seen during a tree inspection. Be discovered a tree appraisal.
Steffen Gottschling is the senior editor of the Ratgeber editorial office. Before 2016 at basenio.de began, he worked in broadcasting and in the online editorial department of a regional daily newspaper. His main topics are the areas of care& Right.