EVALUATION OF MALUS GERMPLASM FOR RESISTANCE TO POWDERY MILDEW AND SCAB

Open pollinated seedlings from 30 small-fruited Malus species and from a few hybrids and varieties were screened for high-level resistance to powdery mildew incited by Podosphaera leucotricha /E11. and Ev./ Salm. under greenhouse conditions.
Seeds were collected in the gene-bank of the Institute of Horticultural Research, East Malling, England.
At the stage of 1–2 true leaves, seedlings were inoculated by the normal conidiospore suspension method, repeated three times.

The evaluation showed that M. hupehensis /100 %/, M. florentina /100 %/, M. sikkimensis /73 %/, M. hupehensis robusta O.P. /68 %/, M. baccata himalayaca /56 %/, M. robusta /43 %/ and M. koreana /42 %/ all produced some seedlings in their progenies that remained free of mildew infection after inoculation.

The seedlings obtained exhibited a number of different reactions to scab ranging from no visible sign of infection, hypersensitivity, necrotic spots with no sporulation, or lesions with varying degrees of sporulation.

The sources of resistance to mildew and scab were certainly related to different genetic backgrounds.
The carriers of resistance against apple scab were descendants of forms with polygenic resistance as well as forms in which resistance depended on major genes.

Fruit Breeding

V. Ognjanov, D. Vujanic-Varga

https://doi.org/10.17660/ActaHortic.1988.224.19