Oat brandy
| Oat brandy | ||||||||||||
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Flying oat brandy ( Ustilago avenae ) |
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| Scientific name | ||||||||||||
| Ustilago avenae | ||||||||||||
| ( Pers. ) Rostr. (1890) |
The oat smut ( Ustilago avenae ) is a highly specialized parasitic smut fungus , of Oats , oat attacks and related species and causes the disease the same in him. Instead of fruit, the infected plants form a black mass of spores , which is spread by the wind.
features
The sori are located in the spikelets , the ovaries are usually completely destroyed. It is also rarely found on the leaves. The spore mass is powdery and dark greenish-brown. The spherical spores are pale greenish-brown, being lighter on one side. They are short prickly and 5 to 8 µm in size. Pure cultures can be grown on potato dextrose agar .
Species delimitation
The prickly spores distinguish the oat brandy from other smut fungi such as Ustilago hordei , which has smooth spores.
Development cycle
Ustilago avenae , a species of the Ustilagomycotina subdivision, is a haplo-dikaryont, i.e. that is, the vegetation body is haploid and there are some dikaryotic stages during fruiting body development . The haploid basidiospores are formed on the basidia , fall off and can reproduce like yeast by sprouting . In this way the fungus can survive saprotrophically for a short time . When two of these haploid spores meet, somatogamy occurs , with two types of crossbreeding (+ and -). After this somatogamy, dikaryotic hyphae develop , which can infect the host. There are two different options:
- In spring, the delicate tissues of young plants are infected as soon as they germinate. This happens through overwintering fire spores . Shortly before the oats bloom, an accumulation of burnt spore deposits arises in early summer.
- In early summer, the ovaries are infected by oat plants that are already in bloom. This has the advantage for the fungus that it can settle in the seed as an endotrophic mycelium without symptoms and thus survive the winter. Finally, in the spring, the seeds containing mycelium germinate into plants that initially develop normally on the outside, until the inflorescence is transformed again into an accumulation of burnt spore deposits in early summer, even with this type of infection.
The incendiary spores are usually formed intercalary from dikaryotic hyphae cells. Then the hyphae cells degenerate and the spores become free. It comes to karyogamy and immediately afterwards the basidiospore germinates under meiosis with a Phragmobasidie (septate), which consists of four cells which produce basidiospores again.
Hosts
The oat brandy grows on species of the genera Arrhenatherum , Avena and Hordeum , and also on meadow gold oats . The oat brandy occurs worldwide in a large number of breeds and varieties.
Combat
Several resistant types of oat were bred to combat flying oat blight . In the case of susceptible varieties, early sowing in spring is recommended; the germination of infected seeds at 7 ° C has a reduced incidence of disease . In the past, seed dressing was carried out with systemic fungicides such as Vitavax ( carboxin ) and mercury treatments such as Ceresan L & M, Chipcote ( methylmercury cyanide ) or Panogen Metox ( 2-methoxyethylmercury acetate ). Nowadays, mixtures of fludioxonil , fluoxastrobin and triazoles such as difenoconazole , tebuconazole or prothioconazole are used for pickling. Hot water treatment is only recommended if the infection rate is over 2%.
literature
- Anton Arland : The oat flight brandy, Ustilago avenae (pers.) Jens. Biological investigations with special consideration of the questions of infection and susceptibility . Diss. Phil. Leipzig 1923. - Zugl. in: Botanisches Archiv Vol. 7, 1924, pp. 70–111.
See also
Web links
Individual evidence
- ↑ Pflanzenenkrankheiten.ch: Oatflight brandy ( Memento of the original from July 14, 2014 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.
- ↑ a b c d e Entry at Mycobank , accessed on March 9, 2012
- ↑ Heinz Gengenbach: Detecting fire diseases in grain in good time ( Memento from February 25, 2013 in the Internet Archive )
- ↑ Plant protection products directory in Switzerland ( Memento of the original from August 3, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
