Puccinia xanthii

Puccinia xanthii is a Ständerpilzart from the order of rust fungi ( Pucciniales ). The fungus is an endoparasite of different cocklebur. Symptoms of infestation by the way are rust spots on the leaf surfaces of host plants. The Verbreitungegebiet includes southern Europe and North America.

• 6.1 Notes and references

Features

Macroscopic characteristics

Puccinia xanthii with the naked eye can be seen only on the basis of the projected on the surface of the host spore deposits. They grow in large nests that appear as reddish to brown spots on the leaf and stem surfaces. Often these spots flow into each other and then form up to 4 cm long crusts on the stems, the affected tissue swells also.

Microscopic features

The mycelium of Puccinia xanthii growing intercellular like all Puccinia species and forms Saugfäden that grow into the storage tissue of the host. The Telien the type are round or oblong. You are surrounded by short, dark brown paraphyses The teliospores are rarely, usually two-celled, oblong to clavate and 36-52 x 16-31 microns in size; its stem is short and light brown.

Dissemination

The Artareal of Puccinia xanthii includes southern Europe and North America with a holarktisches distribution area. Probably native to North America, he was introduced to many countries such as South Africa and Australia.

Ecology

The host plants of Puccinia xanthii are various cocklebur ( Xanthium spp.). Other hosts are the sunflower and the Beifußblättrige ragweed. The fungus feeds on the present in storage tissues of the plant nutrients, its spores bearing later break through the leaf surface and set free spores. The type has a development cycle, from which are known only Telien.

Application

Puccinia xanthii is used in Australia for biological pest control against Xanthium occidentale. To combat ragweed ragweed the way but does not seem to be suitable.

Systematics and Taxonomy

The species is very similar with several grids closely related, all of which occur in South and North America on various composite flowers and differ only in their host. It is therefore proposed that these species all conspecific classified with Puccinia xanthii. Puccinia xanthii is therefore an morphospecies and the remaining modes are classified as varieties. These species are Puccinia melampodii, Puccinia cnici - oleracei and Puccinia semota.