surveillance

In 2016, severe epidemics of yellow (stripe) rust were observed on durum and bread wheat in European regions where the diseases in the past were insignificant or absent. Stem rust was also observed at epidemic levels for the first time in more than 50 years in Europe. On Sicily, both yellow and stem rust caused epidemics on cultivated durum and bread wheat and numerous breeding lines. In 2017, surveys in farmer fields and trial monitoring were carried out in Southern Italy during April-June. A total of 61 farmer fields and 9 experimental plots were inspected and rust samples collected. Despite unfavourable weather conditions for rust development, stem rust, yellow rust and leaf rust were detected on 86%, 50% and 14% of the surveyed sites, respectively. The surveys on Sicily covered approximately 70% of the durum wheat area, and data uploaded and visualised on the Wheat Rust Toolbox. On mainland Italy and Sardinia, yellow rust was observed, and sampled from nine fields in Sardinia and two in Puglia, whereas stem rust was detected and sampled in experimental plots in Sicily, Sardinia, Puglia, Lazio and Emilia Romagna. A total of 94 samples of stem rust, 30 samples of yellow rust, and 3 rust samples from Berberis aetnensis were sent to GRRC. Preliminary results of yellow rust genotyping and race phenotyping showed prevalence of race Triticale2015. Warrior(-) and a new race (Pst'New'- First detected in 2016) were also detected. For stem rust, TTTTF and TTRTF were detected in Sicily and mainland Italy and TKTTF was identified in Sardinia. Susceptibility of major commercial durum cultivars and breeding lines suggests the need for both durable resistance breeding and systematic surveys coupled to an early warning system.

Under changing climatic conditions, the emergence of new diseases or new races of existing diseases is a serious threat to global wheat production. Particularly, the presence of wheat blast in Bangladesh and stem rust race Ug99 in Iran, created a fearsome and intractable situation for Pakistan. A study was planned for monitoring and surveillance of the wheat blast and rust pathogens in wheat growing districts of Punjab, Pakistan during the cropping season 2016-17 as vigilance program. During the survey, one hundred and seventy one wheat fields of upper and central Punjab region were monitored and two types of Rusts (Leaf Rust & Yellow Rust) were recorded in varying intensity on different varieties of wheat. Out of 171 locations 86 spots were free from both types of rusts i.e. Leaf Rust & Yellow Rust, while the remaining locations were found to be infected with both leaf and yellow rust. However, all the surveyed fields were free from the stem rust infestation. Among the infected fields, 23 were infected by Leaf Rust while 63 fields were infected by Yellow Rust.The susceptible type of rust attack was noticed on old/ banned/ unapproved wheat varieties. Moderately resistant to resistant reaction was observed on newly approved varieties. The rust infected samples having S or MS type infection were collected for race analysis. Similarly, blast suspected samples were analyzed in laboratory and none of the tested samples showed the presence of wheat blast pathogen, which indicates no need to panic but vigilant in future.

Wheat rusts, caused by the fungal pathogen Puccinia sp. are serious economic diseases of wheat worldwide. Surveillance, monitoring and new virulence identification are prerequisites for future race prediction and for effective breeding programs. Therefore, we decided to compile the endeavours done for surveillance over eight cropping seasons in Lebanon. The extensive field surveys were conducted yearly in major bread and durum wheat areas over the period 2009-2017 using the Borlaug Global Rust Initiative surveillance protocols. Over eight years, 136 locations were surveyed, 56 samples were collected from mainly stripe and stem rust, and X samples were phenotyped using a robust set of standards differentials lines used worlwide at Tel Hadya - ICARDA, 6 phenotyped at INRA - Grignon, 4 phenotyped at the Global Rust Reference Center (GRRC), until the season 2015-2016 the cereal rust laboratory at LARI became autonomous in race analysis. Six samples were genotyped. The latest phenotyping showed that pathotypes had combinations of the virulence for the widely deployed genes Yr2, Yr6, Yr7, Yr8, Yr9, Yr25 and Yr27 resembling to the aggressive strain PstS2, the invasive high temperature tolerant isolate. Resistance genes Yr1, Yr3, Yr4, Yr5, Yr10, Yr15, Yr17, Yr32, and YrSP were effective against all isolates. Race typing of the stem rust sample using the North American stem rust differential sets indicated presence of TKTTF in surveyed wheat growing areas as well as at ICARDA's research station in Terbol. Identified races have been used in field artificial inoculation of ICARDA's breeding program during the last two years. In conclusion, the races PstS2 and TKTTF were the dominant prevalent races in the country for yellow and stem rust respectively. This information could be useful for the region for better integrated disease management and wider diversification of resistance genes deployment in breeding programs.

Emerging and re-emerging diseases of humans, animals and plants pose a significant hazard to public health and food security. With recent advances in sequencing technology, bacteriologists and virologists are now integrating high-resolution genotypic data into pathogen surveillance activities. However, the application of genomics to emerging filamentous plant pathogens has lagged. To address this, we developed a robust and rapid “field pathogenomics” strategy. We applied this method in 2013 to the wheat yellow rust pathogen Puccinia striiformis f. sp. tritici (Pst), using gene sequencing of Pst-infected wheat leaves taken directly from the field to gain insight into the population structure of a re-emerging pathogen. Our analysis uncovered a dramatic shift in the Pst population in the UK and supports the hypothesis that recent introduction of a diverse set of exotic Pst lineages may have displaced the previous population. Gene sequencing of infected host tissue can also be leveraged to assess the genotype of the host, rapidly confirming whether previously resistant wheat varieties have indeed been overcome. We have now expanded this study to analyze Pst-infected plant samples from across Europe and beyond and will provide an update on the insights we have gained regarding Pst population dynamics. Working with cross-institutional and industrial partners we are now developing this technique further to reduce cost so it can be applied routinely within the U.K. cereal disease surveillance program.