ISHS Acta Horticulturae 525: International Conference on Integrated Fruit Production
BREEDING FOR RESISTANCE TO APPLE SCAB IN BULGARIA |
| Authors: | V. Djouvinov, R. Penev |
| Keywords: | Breeding for resistance, apple scab, Venturia inaequalis /cooke/winter, susceptibility, determining of pathotypes |
| Abstract:
Apple scab (Venturia inaequalis/Cooke/Winter) was first discovered in our country in 1903. Before World War II this disease had been controlled only by 3–4 treatments when the apples had been grown in mixed orchards or in separate ones with wide range of cultivars. Later during the intensification and the concentration of apple industry (after 1960) the average annual sprayings against scab reached 10–16 in number. The longstanding breeding programs for establishing of cultivars resistant to this disease had given their first results in the 70s in USA, Canada, France and Germany. These new cultivars have opened new possibilities for control of the disease. The main objective of the new breeding program which has started in 1986 was to create Bulgarian cultivars resistant to scab. The obtained hybrid seedlings have been artificially inoculated and evaluated according to Chevalier et al., 1990, Lespinasse Y., Remandin S., 1990. The leaf susceptibility of local and foreign cultivars has been estimated using a 6-grade scale. The racial composition for determining of the pathotypes of V. inaequalis is established using an orchard-trap planted with the standard differentiators. In the period 1992–1997 the susceptibility of 37 cultivars has been established as well as the susceptibility of 26 cultivars carriers of Vf, Vr and Vf+poly. During the last 5 years we have not established scab infection on 26 cultivars carriers of Vf, Vr and Vf+poly resistant genes. Among the other 37 cultivars with very low susceptibility are Akane, Paulared, Tydeman's Early, Krimskoe selekcionnoe. Races 1,2 and 5 were established in the orchard-trap during the investigation period. So far the hybrids obtained from the crossing Mollie's Delicious x Prima, Starkrimson n 142 (Golden Delicious x M.zumi), Greensleeves x Liberty etc. are promising. | |
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