Escalating Threat of Wheat Rusts

Abstract

Russia, at the International Wheat Conference to discuss the world's most widely planted crop. This came on the heels of a Borlaug Global Rust Initiative (BGRI) workshop that focused on the rapidly spreading fungal diseases known as wheat rusts, which are causing epidemics that require urgent action. If we are to prevent devastating crop losses, nations must coordinate to enact short-term solutions; they must also expand long-term efforts in research, plant breeding, and surveillance. In the 1940s, American agronomist Norman Borlaug led the charge against wheat stem rust that threatened farmers in Mexico. By breeding new plant varieties to resist the causative pathogens, he spurred a Green Revolution that has held this worldwide threat in check since the 1970s. But in 1999, a virulent fungal strain (Ug99) was detected in Africa, making most commercial wheat varieties around the world vulnerable to stem rust once again.* While the world remains in fear of stem rust, large-scale epidemics caused by new virulent and aggressive strains of yellow rust fungus (also known as stripe rust) now pose a severe threat to the world's wheat supply. Since 2000, the United States and Australia have faced severe yellow rust epidemics. Even more alarming, last year yellow rust devastated major wheat-producing areas in China, northern and eastern Africa, western and central Asia, and the Middle East. The presence of two virulent and highly aggressive yellow rust strains (PstS1 and PstS2) at high frequencies at epidemic sites on fi ve continents (including Europe) may represent the most rapid and expansive spread ever of an important crop pathogen. This epidemic trend may continue because the aggressive strains, which can tolerate higher temperatures, are still evolving. Short-term responses to ongoing rust epidemics are limited to fungicide sprays, which may be unaffordable or unavailable in poor countries. Rapid replacement of the wheat most susceptible to rust with locally adapted, resistant, or less susceptible varieties is needed to slow down future spread. Any sustainable solution must involve political commitment; increased and coordinated international surveillance and monitoring; breeding for durable rust resistance; seed multiplication; and training of pathologists, breeders, and new young scientists. Fundamental research covering rust biology and epidemiology, evolutionary genetics, and rust-wheat interactions will also be required. For stem rust, such coordinated efforts have been successfully established by the BGRI and the Food and Agriculture Organization of the United Nations, which last month launched the Rust SPORE Web portal to track the advance of Ug99. However, similar combined efforts are lacking for yellow rust, and the creation of an analogous reaction force will require substantial fi nancial support. The recent agreement by the BGRI Executive Committee and international experts at the St. Petersburg meeting to establish a Global Rust Reference Center (GRRC) that targets all wheat rust fungi would unify and i...

Management of wheat rusts at different growth stages using Nativo 300 SC (trifloxystrobin 100g/L+tebuconazole 200g/L) fungicide

“…Wheat yellow (stripe) rust is also a significant disease of wheat worldwide (Chen, 2005;Hovmoller et al, 2010;Wellings, 2011). Yellow rust epidemic has been reported in South Africa, Kansas, China and Central Asia (Morgounov et al, 2004;Wan et al, 2004;Chen et al, 2005).…”

Application of Phenotypic and Molecular Markers to Combine Genes for Durable Resistance against Rust Virulences and High Yield Potential in Wheat

“…Rusts being important worldwide are known for their ability to mutate and multiply rapidly and to use their air-borne dispersal mechanism from one field to another and even over longer distances. Rusts are currently the most important diseases of wheat worldwide, which threaten global food security (Hovmøller et al, 2010). Major wheat growing areas of the world are facing repeated severe yellow rust epidemics since 2000, when two highly aggressive and high temperature tolerant Pst strains appeared (Hovmøller et al, 2008).…”

Wheat Stripe Rust Resistance Protein WKS1 Reduces the Ability of the Thylakoid-Associated Ascorbate Peroxidase to Detoxify Reactive Oxygen Species

“…Among these, Puccinia striiformis f. sp tritici (Pst), the causal agent of wheat stripe rust (also known as yellow rust), is responsible for major yield losses in most wheat-producing areas. Recent worldwide epidemics are associated with the emergence of new virulent and highly aggressive Pst races that are now found at high frequencies on five continents (Milus et al, 2009;Hovmøller et al, 2010). The most effective and environmentally friendly strategy to limit yield losses caused by Pst has been the deployment of resistance genes, which for yellow rust are known as Yr genes (McIntosh et al, 2013;Maccaferri et al, 2015).…”