ABSTRACT
Mexico, DF, Mexico. 3 USDA-ARS, Cereal Disease Laboratory, University of Minnesota, St. Paul, MN 55108
(retired). * Corresponding author: j.huerta@cgiar.org
The cereal rusts as diseases, reduce the quantity and quality of wheat yields. Losses due to stem, leaf and stripe rusts have been enormous over the years. Despite the great progress made in their control, the rusts are still the most important wheat diseases worldwide. There are three rusts which belong to the genus Puccinia, and differ not only in their morphology and life cycle, but also in their environmental conditions for growth. The pathogens Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn., P. triticina Erikss., and P. striiformis Westend. f. sp. tritici Eriks. & E. Henn., are widely distributed around the world and all are generally asexually reproduced, but have the capacity to evolve into new virulent forms able to attack previously resistant hosts through mutation. The rust is named for the dry, dusty yellow-red or black spots and stripes (sori or pustules) that erupt through the epidermal tissues of the leaf or stem in a susceptible or moderately susceptible cultivars. In general, the size and surrounding coloration of the rust pustules determine the specifi c infection types which can be chlorotic fl ecks, necrotic spots or the infection may result into sporulating pustules of various sizes. The rust fungi are also able to produce large amounts of urediniospores which are effective in long distance dissemination. The rust diseases increase rapidly causing serious losses, making the rusts the most devastating diseases of wheat.
