The Ug99 race of wheat stem rust, a fungal disease, emerged in eastern Africa in the late 1990s and has spawned 13 new strains, spreading to 13 countries. Ug99 is highly-virulent for nearly all popular wheat varieties. The national research programs in Ethiopia and Kenya have supported the yearly screening of as many as 50,000 wheat lines from breeding programs worldwide under strong natural Ug99 infections, allowing rapid development of new, resistant varieties. Enough seed has been multiplied so many countries in the projected path of Ug99’s spread are safe from serious outbreaks. Another stem rust race group known as TKTTF has spread to over a dozen countries in Africa, Asia, and Europe, since its detection in Turkey in 2005.
Long confined to South America, the mysterious fungal disease known as wheat blast suddenly appeared in Bangladesh in 2016, causing 25-30 percent losses on 15,000 hectares of wheat and threatening to spread quickly throughout South Asia’s vast wheat lands, where no varieties are resistant. CIMMYT and CGIAR Research Program on Wheat (WHEAT) partners are at the center of an urgent global response to monitor, characterize and control blast and, especially, to develop and deploy resistant wheat varieties.
A moth from the Americas that appeared in Africa in 2016 and whose larvae feed on numerous crops, the fall armyworm is able to destroy as much as 70 percent of a maize harvest and, once adult larvae are established, is not easily controlled by pesticides. Scientists from CIMMYT and the International Institute of Tropical Agriculture (IITA) are working with partners worldwide on integrated approaches including chemical and biological controls, resistant varieties, agronomic management, and tracking and early-warning systems.
Involving a deadly alliance of two viruses and first reported in eastern Africa in 2011, MLN disease kills plants before they can grow, and the pathogens are transmitted by insects or contaminated seed. Serious damage to the region’s maize has led many farmers to stop growing the crop. Progress to counter MLN includes the production and distribution of resistant hybrids.
Text: Clyde Beaver, Bianca Beks, G. Michael Listman,
Contributors: Hans Braun, Dave Hodson, Jennifer Johnson, B.M. Prasanna, Ravi Singh
Photos: CIMMYT archives
Graphics: Gerardo Mejía, Bosen Zhou
Editors: Bianca Beks, G. Michael Listman, Julie Mollins, Geneviève Renard