Septoria nodorum blotch of wheat

Septoria nodorum blotch occurs in wheat-growing areas worldwide, but the disease is more prevalent in areas with warm and moist weather, such as the southeastern United States, parts of Europe, southern Brazil, and Australia. The disease affects both the quantity and quality of yield, and the pathogen is capable of affecting wheat at both seedling and adult stages. Historically, losses up to 50% have been reported, in addition to lower grain quality, although in the U.S., lower levels of loss are typical. The yield losses are highest when flag leaf, F-1 (leaf below flag leaf), and F-2 (leaf below F-1) are infected. The disease is known to reduce thousand-kernel-weight, a yield parameter. The fungus undergoes regular cycles of sexual recombination due to the availability of both mating types, and creates genetic variation in its population, thus enhancing its potential to overcome control measures. The pathosystem is also a model system for necrotrophic plant pathogens. So far, nine necrotrophic effectors and host susceptibility gene interaction have been identified, which have the potential to be used in marker assisted selection for breeding resistant wheat varieties.