The EUCARPIA Multi-site Rust Evaluation—Results 2010

Abstract

The EUCARPIA multi-site rust evaluation was repeated in 2010 for the fourth time. The trials were sown at 24 sites in 11 countries in Europe. The 20 Italian/Hybrid (Lolium multiflorum and L. boucheanum, respectively) and 34 perennial ryegrass (L. perenne) cultivars were sown in separate trials. The cultivars were grown as rows in a completely randomized block design with four replicates. Rust incidence was scored in the year of seeding by each of the participants. The method used to test cultivars for rust resistance was based on an estimation of the percentage of leaf area affected. Crown rust (Puccinia coronata f. sp. lolii) was again the most frequently observed rust on both ryegrass species. Stem rust (P. graminis f.sp. graminicola) was reported at only one site for Italian and at four sites for perennial ryegrass. Variation in resistance to crown rust among cultivars was significant at 17 sites for Italian and at 16 sites for perennial ryegrass. The cultivars ‘Tarandus’, ‘Gosia’, ‘Caballo’ and ‘Domino’ showed the highest level of resistance of all the Italian ryegrass cultivars tested. ‘Gwendal’ and ‘Bocage’ were the most crown rust resistant perennial ryegrass cultivars. The ranking of the mean crown rust susceptibility of the cultivars was highly correlated with the corresponding ranking of cultivars in the 2001, 2004 and 2007 trials, respectively. This was true for both perennial and Italian ryegrass. Coefficients of rank order correlations of average cultivar disease scores between the years were greater than r_s = 0.97 (p < 0.05) for Italian and r_s = 0.86 (p < 0.05) for perennial ryegrass, respectively. Therefore, there is no evidence that crown rust resistance of an individual cultivar was overcome by the rust pathogen over the 9 years of experimentation.