Stem rust fungus. Different from most fungi, the rust variations have five spore stages and alternate between two hosts. Wheat is the primary host, and barberry is the alternate host. There are multiple pathotypes (including QCC and MCC) affecting barley, within "forma specialis tritici". The stem rust fungus attacks the parts of the plant that are above ground. Spores that land on green wheat plants form a pustule that invades the outer layers of the stalk. Infected plants produce fewer tillers and set fewer seed, and in cases of severe infection the plant may die. Infection can reduce what is an apparently
Stem rust studied the stem rust. Thirty years later it received its name, "Puccinia graminis", by Persoon, and in 1854 brothers Louis René and Charles Tulasne discovered the characteristic five-spore stage that is known to some stem rust species. The brothers were also able to make a connection between the red (urediniospore) and black (teliospore) spores as different stages within the same organism, but the rest of the stages remained unknown. Anton de Bary later conducted experiments to observe the beliefs of the European farmers regarding the relationship between the rust and barberry plants, and after successful attempts to connect the basidiospores