Which genes of apple scab resistance keep control against pathogen V. inaequalis in future?

摘要

Attacks of apple scab on the collection of genotypes carrying particular scab resistance genes (Bus et ai, 2009) in locality Holovousy (the eastern Czechia) from 2011 to 2013 was the objective of this study. Evaluations were done after primary infections on leaves on genotypes planted in spring 2010 into randomized blocks with five repetitions. Severity was assessed according to the scale 1-9 (Lateur and Populer, 1994). The genotype H(1) 'Golden Delicious' was infected by pathogen V. inaequalis withhigh intensity in the grade from 6.8 to 9.0. Attacks on the next scab sensitive genotype H(0) 'Gala' were also high in the grade from 4.8 to 9.0. Only genotypes H(5) 9-AR2T196, H(7) M. floribunda 821, H(11) 'Hansen's baccata #2 and H(15) GMAL 2473 remained healthy without any damage. Remaining genotypes were infected. Genotypes H(4) TSR33T239, H(14) 'Dulmener Rosenapfel', H(9) J34, H(2) TSR34T15 and H(13) 'Durello di Forli' were infected in very low rate in maximum grade 1.6; 1.7; 2.0; 2.4 and 2.8 respectively. Infections on genotype H(3) Q71 were recorded in maximum grade 5.8. Severe symptoms of the disease were recorded on the genotype H(8) B 45 in maximum grade 6.2. Genotype H(6) 'Priscilla' were infected in the last year of evaluation in grade 2.3while H(7) M. floribunda 821 was not attacked indicating occurrence of race no. 6 of pathogen V. inaequalis in this location. Spreading of apple scab races overcoming genes Rvi6 that is the most involved genes in scab resistant cultivars reduce their growing. Cultivars carrying scab resistance genes that are not yet attacked by scab and cultivars with polygenic resistance are promise for breeders and growers.