Stem rust

The stem, black,Prof. K.C. Mehta and cereal rusts are caused by the fungus Puccinia graminis and are a significant disease affecting cereal crops. Crop species that are affected by the disease include bread wheat, durum wheat, barley and triticale. These diseases have affected cereal farming throughout history. Prof. K.C. Mehta has done a lot of hard work life cycle of Puccinia (also called the 'rust cycle') was discovered by Prof. K.C. Mehta. Since the 1950s, wheat strains bred to be resistant to stem rust have become available. Fungicides effective against stem rust are available as well. In 1999 a new virulent race of stem rust was identified that most current wheat strains show no resistance against. The race was named TTKSK (e.g. isolate Ug99), named after the country where it was identified (Uganda) and the year of its discovery (1999). It spread to Kenya, then Ethiopia, Sudan and Yemen, and is becoming more virulent as it spreads. An epidemic of stem rust on wheat caused by race TTKSK is currently spreading across Africa, Asia and the Middle East and is causing major concern due to the large numbers of people dependent on wheat for sustenance. Scientists are working on breeding strains of wheat that are resistant to UG99. However, wheat is grown in a broad range of environments. This means that breeding programs would have extensive work remaining to get resistance into regionally adapted germplasms even after resistance is identified. An outbreak of another virulent race of stem rust, TTTTF, took place in Sicily in 2016, suggesting that the disease is returning to Europe. Comprehensive genomic analysis of Puccinia graminis combined with plant pathology and climate data has pointed out the potential of the re-emergence of stem wheat rust in UK. There is considerable genetic diversity within the species P. graminis, and several special forms, forma specialis, which vary in host range have been identified. P. graminis is a member of the phylum Basidiomycota within the kingdom Fungi. The characteristic rust color on stems and leaves is typical of a general stem rust as well as any variation of this type of 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 healthy crop about three weeks before harvest into a black tangle of broken stems and shriveled grains by harvest. Stem rust of cereals causes yield losses in several ways: