ISHS Acta Horticulturae 538: Eucarpia symposium on Fruit Breeding and Genetics
SCAB ATTACK IN AN APPLE SEEDLING FIELD AND THE RELATIONS BETWEEN FRUIT AND LEAF SCAB |
| Author: | H. Schmidt |
| Keywords: | apple, scab, breeding |
| Abstract:
It is generally accepted that there is a close correlation between leaf and fruit scab in apples. This is the basis of testing apple seedlings in the seed box by artificial inoculation with scab spores. It was our impression quite often that there is more scab on the fruit than is seen on the leaves. We therefore, had a closer look at leaf and fruit scab in more than 1.000 seedling trees of seed year 1993. Since 1986 a new scab race, race 6, has been observed in the Ahrensburg fields. From a differential set, interplanted between the seedling rows, it was known, that race 1 is predominating. Races 2 and 4 do not exist in this field. Race 3 induces slight symptoms and of race 5 slight attack was observed in 1998 for the first time. Race 6 is present. From marker analysis we know that the Vf gene can be present even though up to 20% of the leaf area show sporulating scab. From the onset of fruiting, leaf and fruit scab could be compared. The relation turned out to be less strong as is generally accepted. The calculation of the correlation coefficient from more than 1.000 data pairs gave a highly significant r = 0,61 value.All progenies with more than 20 plants have significant r values, however, variation between the families ranged from r = 0,41 to r = 0,82. | |
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