Susceptibility of European rice varieties to blast

Over the years, I have had the opportunity to take part in multi-year, multi-environment field trials assessing the susceptibility of many European (mostly Italian) rice varieties to rice blast, caused by Magnaporthe grisea (T.T. Hebert) M.E. Barr. The trials were conducted under open-field, natural infection conditions. Their management was designed to favour the pathogen as much as possible through late sowing, high nitrogen input, sandy soil, and the endemic presence of the pathogen in the area. The experimental design included “spreader rows” (plots sown with a highly susceptible rice variety) to further promote disease development and spread. Information on the degree of genetic resistance of the tested varieties has been reported in two peer-reviewed articles (Mongiano et al., 2021; Titone et al., 2015) and one book (Tamborini et al., 2021).

However, some of these assessments are now more than ten years old and, given the pathogen’s high mutation rate, they may be outdated. Even within the short interval between our first and last trial we observed a decline in the degree of genetic resistance in some reference varieties. Morover, many new varieties have been registered in the European Common Catalogue since our last publications. This underscore the importance of continously supporting this type of effort. Genetic resistance remains the most effective, environmentally-friendly, and economical method for rice blast control. Comprehensive, up-to-date knowledge of the susceptibility of rice genetic resources is fundamental to plan control strategies and optimize cultivar selection.

Variety classifications

A list of all the tested varieties, grouped by the resistance class determined during the studies, is reported below. The classification method was defined based on the literature available at the time of the trials and on prior experience. Detailed information is provided in the referenced papers. A variety was included only if it had been tested for at least two independent seasons.

References