Shotgun Sickness
The shotgun disease ( English shot hole disease ) is one of the fungal Wilsonomyces Carpophilus (= Stigmina carpophila (Lev.) MB Ellis (= Clasterosporium carpophilum caused)) plant disease .
description
The disease first shows itself as lightened points on young leaves of various stone fruit species, which turn reddish-brown after a few days. The plant starts a defense reaction in which the fungus is excluded. As a result, after about two weeks, the necrotic tissue within the spots break out and leave 1-10 mm large, red-rimmed holes. The foliage looks like it has been riddled with pellets, especially when it is heavily infested, hence the name. It yellows and falls off prematurely.
Blackish, sunken points or spots with a red border form on the fruit. These fruits cripple, tear open, dry up or rot and are rejected.
The disease mainly affects plums , plums and cherries , but also other types of stone fruit ( mirabelle plums , peaches , cherry laurel , ornamental cherry , almond ). Different types of cherry are susceptible to different degrees. According to the Weihenstephan University of Applied Sciences , the following varieties are less susceptible:
- 'Abel's Late'
- 'King's cherry type Gatterstedt'
- 'Büttner's Red Cartilage'
- 'Hausmüller medium thickness'
There is also damage to shoots, especially in the peach. The shoots then also get brown, red-rimmed spots of round to elongated shape, on which rubber usually emerges. If thin shoots are covered by the spots, they die. Cancerous galls are formed on thicker shoots through defense reactions of the tree .
The pathogen is so far only known in its asexual form. It overwinters on the bark, at shoot infestation sites and fruit mummies with a shoot mycelium and conidia that are very resistant to drying out and low temperatures .
In damp, cool, rainy spring weather, it multiplies explosively. There is therefore little infestation in areas with little precipitation. Areas with frequent and intensive fog formation, which leads to the deposition of dew, are particularly at risk (high altitude in the low mountain range). The conidia are spread by raindrops. The fungus penetrates the tissue directly through the epidermis or through stomata . Since the newly formed spores at the infection sites are washed away when it rains, the lowest leaves are often most affected.
Older foliage (from July) is hardly infected anymore because it has become too resistant and the temperatures at this time of year are no longer ideal for the fungus. For this, the infection of young shoots sets in at this time, which continues until autumn. The fungus mainly penetrates through the attachment points of the fallen leaves.
Immediately after the leaf falls, late infections are again possible in damp weather. The preferred entry points are the not yet corked leaf attachment points, which are located directly below the buds that have developed for the next year. From there, the fungus penetrates the shoot, destroying the "eyes" and the surrounding bark tissue.
The massive occurrence of shotgun disease leads to premature leaf fall, shoot death, rubber flow and crop failure.
Measures in integrated crop production
One to four fungicide injections are recommended in infested locations, especially if there was massive infestation from the previous year. In the case of persistently damp weather in spring, the first treatment is carried out when budding, and further treatments every ten to fourteen days. It is important that the treatment takes place during leaf development. Treatment with a copper preparation is also recommended for leaf fall. Measures with copper before flowering only have an infestation-reducing effect.
Infested leaves and fruit mummies should be removed to reduce the pressure of infestation. Heavily infested trees are cut back. In addition to reducing the infestation pressure, this also causes the crown to dry more quickly after rainfall. Infested shoots are mainly removed from peach trees. To prevent late-stage infections on the shoots, peach trees should be sprayed with copper preparations or the synthetic fungicides already used in summer immediately before the leaves fall.
Coordinated fertilization, especially cautious nitrogen fertilization, also inhibits the infestation pressure somewhat.
Measures in organic farming
The Research Institute for Organic Agriculture FIBL recommends alumina preparations and network sulfur or copper against the shotgun disease. Another recommended preventive measure is mulching the tree grate and planting it with garlic or onions.
Diseases with similar symptoms
- Bacterial blight Pseudomonas morsprunorum
- Plum shot disease Phoma prunorum
- Sieve holes in the plum Sphaceloma pruni
The latter two, however, are of little importance and are included in the fight against shotgun disease.
literature
Books
- Georg Vukovits: The most important fruit diseases . 2nd Edition. Leopold Stocker Verlag, Graz 2000, ISBN 3-7020-0635-4 .
- Leonhard Steinbauer, Robert Strahlhofer, Herbert Muster, Georg Innerhofer: Zwetschke. Cultivation, pruning, varieties, processing. (Professional guide fruit). Österreichischer Agrarverlag, Leopoldsdorf 2005, ISBN 3-7040-2025-7 .
- Gerhard Friedrich: Handbook of fruit growing . Neumann Verlag, Radebeul 1993, ISBN 3-7402-0116-9 .
- Eduard Lucas (Gre.); Hermann Link (Ed.): Lucas' instructions for fruit growing . 32nd edition. Verlag Eugen Ulmer, Stuttgart 2002, ISBN 3-8001-5545-1 .
Magazines
- Plant protection in commercial fruit growing 2006 . Verlag Eugen Ulmer, Stuttgart (the magazine was published between 1987 and 2011 on behalf of the State Institute for Plant Protection in Baden-Württemberg).
- Fruit growing. Volume 31 (2006), Issue 2, ISSN 0179-7077 .
- Fruit and garden. Vol. 125 (2006), Issue 3, ISSN 0029-7798 .
Individual evidence
- ↑ a b Thomas Lohrer: Shotgun disease. March 2010. (Information sheet from the State Research Institute for Horticulture Weihenstephan at the Weihenstephan Triesdorf University of Applied Sciences) (PDF; 69 kB) ( Memento of the original from April 8, 2011 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Marianne Klug in: Question and Answer. Agricultural weekly paper, Westfalen-Lippe 38/2012, pp. 6-7.
Web links
- Stigmina carpophila in woody diseases in words and pictures