Puccinia

Cereal stem rust (Puccinia graminis ) on wheat

Puccinia are a very extensive fungal genus of the family of Pucciniaceae in the order of the rust fungi ( Pucciniales ). All species of this genus cause plant diseases, which are referred to as rust. Virtually all cereals except rice can be attacked by Puccinia species, which can lead to significant yield losses.

• 4.1 Indirect
• 4.2 direct

Features

Macroscopic characteristics

With the naked eye, only the protruding on the surface of host plant spore can be seen in the rule. These grow in nests, which usually appear as spots and pustules on the leaf surfaces. The raised spots are usually brown, sometimes yellow to orange. The color and tactile appearance is reminiscent of iron rust and was eponymous for the whole order.

Microscopic characteristics

The mycelium of all Puccinia species grows and forms intercellular Saugfäden that grow in the storage tissues of the host.

Dissemination

The genus includes about 4000 species. Individual species are regionally limited. But especially the grain pests are widespread synanthropic world.

Ecology

The fungi feed on the present in storage tissues of the plant nutrients, their spores bearing later break through the plant surfaces on leaves or stems, and put spurs free. Many Puccinia species undergo during their development cycles vegetative five stations, which mostly spread on two different hosts. The greater the harmful effect on important crops, the more intense the development cycles of each type were studied. A good example of this is the ecology of cereal stem rust. Where cereals such as wheat as the main hosts and barberries are attacked as an intermediate host.

The Malvenrost (Puccinia malvacearum ) draws by any change of host and spends its life cycle on different Mallows and Marshmallow species. He is only Telien and is thus micro- cyclically.

When corn rust (Puccinia sorghi, P. Syn mayidis ) the infection of maize plants via a transmission from infected sorrel species that must be present within a radius of a few meters. In the optimal type, microclimate conditions with repeated high humidity occurs in the for cultivation typical dense stands to epidemic epidemics.

Combat

Indirectly

With an interruption of the life cycle of the spread of species that develop on two different hosts can be controlled indirectly. For this, the intermediate hosts are often suppressed by selective weed control with herbicides rarely by weeding or Roden. In infected areas should be avoided in addition to the cultivation of susceptible varieties and crop residues are carefully plowed under. Before the direct link has been demonstrated between in close proximity to areas planted with cereals growing barberry and the occurrence of cereal stem rust, you have already tried early in 1660 to eradicate barberry to combat the infestation of the crop with grain black rust. However, this was only partially successful, since many Puccinia species, the uredospores are capable of overwintering. When sowing of winter cereals can be infested in the fall through this the seed. Another indirect method of control is the breeding of resistant crop varieties. Again, this is only partially or temporarily successful, as to the large number of species Puccinia quite a few varieties and forms are caused by mutation or crossover that can overcome resistance newly bred plant varieties. An example of this are the over the long cultivation time incurred by grain varieties and forms of cereal rust black.

Directly

A direct chemical control is possible with fungicides. However, this is controversial and the use of plant protection products must usually be repeated several times.

Types (selection)

A selection of Puccinia species and cultivated plants that infest this:

• Puccinia graminis - affects various cereals, such as wheat, barley, oats and rye
• Puccinia striiformis - affects various cereals, such as wheat, triticale, barley and rye rare
• Puccinia sorghi, P. Syn mayidis - attacks maize crops
• Puccinia hordei - infects barley crops
• Puccinia triticina - invading wheat crops
• Puccinia poae - nemoralis and Puccinia poarum - infested lawn and pasture grass
• Puccinia allii - affects different Lauche
• Puccinia asparagi - affects different asparagus