Researchers have discovered that a fungus that attacked wheat crops in Sicily last year is a new strain. University of Cambridge researchers also warned that spores from the new pathogen could spread to infect new areas of Europe this season, which would be a major problem for the world’s largest wheat producing region.

Lab tests of stem rust that affected crops last year have revealed it is part of a new, highly virulent race, that can infect wheat varieties with good disease resistance. The rust affected several thousand hectares of both durum and bread wheat in Sicily last summer in one of the largest stem rust outbreaks Europe has seen in recent decades.

The infection was first discovered in April last year, in experimental plots in the Palermo province of Sicily. The new strain was identified by the Global Rust Reference Centre (GRRC) at Aarhus University, Denmark, and scientists at the John Innes Centre in the UK are in the process of working out the strain’s genetic make-up.

Researchers said the scale of the outbreak means the stem rust will have produced a large number of spores, suggesting the disease’s spread to new areas in the 2017 season is likely. They said this depends on the new rust strain’s ability to overwinter and cause early infections - both factors are currently unknowns - but it’s certain that susceptible wheat varieties have been planted in Italy and Sicily in 2016/17. Scientists from Cambridge and the Met Office have mapped the likely distribution of spores from infected crops last year; mainland Italy is at a high risk of outbreaks, and Western Greece, Bosnia and Albania are at a lower risk.

Though it’s unlikely, it is possible that stem rust spores travelled as far as Southern England in May last year.  

The new rust strain is unrelated to the feared Ug99 strain, which emerged in the 1990s and devastated crops where it hit. Most commercial wheat varieties were susceptible to Ug99, though it never reached large wheat producing regions.

On Thursday, GRRC recommended that farmers and government bodies be made aware of the potential risks from stem rust in 2017, that preparations are made in at-risk regions, and that new wheat varieties are screened for resistance to the new strain. Researchers in the UK are currently looking at the susceptibility of commercial crops to the stem rust strain.

GRRC also warned that two new strains of yellow rust have been identified over large areas for the first time. One strain is affecting parts of Europe and North Africa, the other East Africa and parts of Asia.