Telium, plural telia, are structures produced by rust fungi as part of the reproductive cycle. They are typically yellow or orange drying to brown or black and are exclusively a mechanism for the release of teliospores which are released by wind or water to infect the alternate

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

in the rust life-cycle. The telial stage provides an overwintering strategy in the life cycle of a parasitic

heteroecious A heteroecious parasite is one that requires at least two hosts. The ''primary host'' is the host in which the parasite spends its adult life; the other is the ''secondary host''. Both hosts are required for the parasite to complete its life cycle ...

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

by producing teliospores; this occurs on cedar trees. A primary aecial stage is spent parasitizing a separate host plant which is a precursor in the life cycle of heteroecious fungi. Teliospores are released from the telia in the spring. The

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s can spread many kilometers through the air, however most are spread near the host plant.

Host plants

There are a number of plants that can be infected by the telial stage. Therefore, the telial stage is considered a

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

to those plants. A few specific plant pathogenic species are listed here with their

hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ( ...

. # ''

Puccinia graminis Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus ''Puccinia graminis'', which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum whe ...

'' or known commonly as black stem rust. It infects many different cereal crops. # '' Gymnosporangium juniperi-virginianae''. It infects the eastern red cedar. This is shown to the right. # ''

Gymnosporangium sabinae ''Gymnosporangium sabinae'' (also ''Gymnosporangium fuscum'' and other names) (pear rust, European pear rust, or pear trellis rust) is a fungal heteroecious plant pathogen with ''Juniperus'' (juniper trees and shrubs) as the primary ( telial) ho ...

''. It infects pear trees. File:Stem rust close up.jpg, ''

'' on wheat. File:Gymnosporangium sabinae fg05.JPG, ''

'' on a pear tree leaf.

Spore stages

The life cycle of rust fungi can have up to five different spore stages and can get quite complex.Schumann, G.L. et al. 2010. Essential Plant Pathology. American Phytopathological Society. Second Edition. St. Paul. pp. 43–44 These stages are: * Stage 0: Pycniospores * Stage I: Aeciospores * Stage II: Urediniospores * Stage III: Teliospores * Stage IV: Basidiospores File:Puccina graminis lifecycle.gif, Life Cycle of ''Puccina graminis''

References

Fungal morphology and anatomy Reproduction {{plant-disease-stub