Puccinia

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Puccinia
Black rust (Puccinia graminis) on wheat

Black rust ( Puccinia graminis ) on wheat

Systematics
Department : Stand mushrooms (Basidiomycota)
Subdivision : Pucciniomycotina
Class : Pucciniomycetes
Order : Rust mushrooms (Pucciniales)
Family : Pucciniaceae
Genre : Puccinia
Scientific name
Puccinia
Persoon

Puccinia are a very extensive genus offungifrom the family of the Pucciniaceae in the order of the rust fungi (Pucciniales). All species in this genus cause plant diseases known as rust. Practically all types of grain, with the exception of rice, can be attacked by Puccinia species, which can lead to significant yield losses.

features

Macroscopic features

As a rule, only the spore beds protruding on the surface of the host plants can be seen with the naked eye. These grow in nests that usually appear as spots and pustules on the leaf surfaces. The raised spots are usually brown, sometimes yellow to orange. The color and haptic appearance is reminiscent of iron rust and gave the whole order its name.

Microscopic features

The mycelium of all Puccinia species grows intercellularly and forms suction threads that grow into the host's storage tissue.

distribution

The genus includes over 4000  species . Individual species are regionally limited. But the grain pests in particular are widespread worldwide as crop followers .

ecology

Life cycle of black rust (
Puccina graminis ), using the example of wheat and barberry

The fungi feed on the nutrients present in the storage tissue of the plants, their spore beds later break through the plant surfaces on leaves or stems and release spores . Many Puccinia species go through five vegetative stations during their development cycle , which are usually distributed between two different hosts . The greater the harmful effect on important cultivated plants, the more intensively the development cycles of the individual species were examined. A good example of this is the ecology of black grain rust . Whereby cereals such as common wheat as main hosts and barberries as intermediate hosts are attacked.

The mallow rust ( Puccinia malvacearum ), on the other hand, does not change host and spends its life cycle on different mallow and marshmallow species. It only forms tele-lines and is therefore microcyclic.

In the case of maize rust ( Puccinia sorghi, syn. P. mayidis ), the maize plants are infected by the transmission of infected sorrel species , which must be present within a few meters. Under optimal microclimatic conditions for the species with repeatedly high humidity, epidemic epidemics occur in the dense stands typical of grain cultivation .

Combat

Indirectly

With an interruption in the life cycle, the spread of species that develop on two different hosts can be controlled indirectly. For this purpose, the intermediate hosts are often pushed back by targeted weed control with herbicides, less often by weeding or clearing . In addition, the cultivation of susceptible varieties should be avoided in infected areas and crop residues should be carefully plowed in. Before the direct connection between barberries growing in close proximity to cereal-growing areas and the occurrence of black rust from grain was proven, attempts were made early around 1660 to eradicate barberries in order to combat the black rust infestation of the grain. However, this was only partially successful, as in many Puccinia species the uredospores can also overwinter. When sowing winter cereals , the seeds can be attacked in autumn. Another indirect control method is the breeding of resistant crop varieties. This, too, is only partially or temporarily successful, since, in addition to the large number of Puccinia species, there are also a number of varieties and forms that arise through mutation or crossing , which can overcome the resistance of newly bred cultivated plant varieties. An example of this are the varieties and forms of black rust from grain that emerged over the course of the long cultivation time of grain .

Directly

Direct chemical control is possible with fungicides . However, this is controversial and the use of pesticides must be usually repeated several times.

Types (selection)

A selection of Puccinia species and the crops that attack them:

Further

Individual evidence

  1. See Paul M. Kirk, Paul F. Cannon, David W. Minter, JA Stalpers: Dictionary of the Fungi . 10th edition. CABI, Wallingford 2008, ISBN 978-0-85199-826-8 , pp. 576 .
  2. a b Forst.TU-München.de: Wood diseases - Barberry - Berberis vulgaris L. Rost (grain rust) ( Memento of the original from June 10, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.forst.tu-muenchen.de
  3. a b Spektrum.de: Compact Lexicon of Biology - Uredinales
  4. agrarservice.de: Rust diseases of the grain ( Memento of the original from June 16, 2013 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. @1@ 2Template: Webachiv / IABot / www.agrarservice.de

Web links

Commons : Puccinia  - collection of images, videos and audio files