PATHOGENICITY OF VIRULENT VENTURIA INAEQUALIS STRAIN ON FOUR APPLE CLONES (MALUS SP.)

In the frame of the European DARE project, 36 apple cultivars, including scab susceptible controls, some V_f resistant cultivars and some partially resistant ones, were confronted by several European local inocula and monoconidial strains in glasshouse conditions.
Of these strains, EU-NL-24, which showed susceptible symptoms on several resistant cultivars (V_f or V_g genes) and Malus floribunda 821, was studied.
In this study, we compared the macroscopic and microscopic symptoms of expression of 4 Malus clones inoculated with this strain.
Leaf samples were collected once the different symptoms appeared.
Leaf surfaces were examined with a scanning electron microscope.
Different parameters were assessed: amount of mycelium, conidiogenesis intensity and host reaction.
The susceptibility level and the intensity of the resistance reaction varied significantly between the cultivars.
The same strain of V. inaequalis could trigger very distinct symptoms according to the cultivar. ‘President Roulin’ showed very specific behaviour with mixing of symptoms on the same leaf. Malus floribunda clone 821 expressed a slight susceptible reaction, this clone is overcome by EU-NL-24 but an important residual resistance is observed.

XI Eucarpia Symposium on Fruit Breeding and Genetics

M. Chevalier, C. Bernard, L. Parisi, C. Audrain, M. Tellier, F. Laurens

resistance, scanning electron microscope, symptoms, conidiogenesis, host reaction, residual resistance

https://doi.org/10.17660/ActaHortic.2004.663.31