The histology of lesion development in raspberry canes infected by Elsinoe veneta

Williamson, B.; McNicol, R.J.

doi:10.1111/j.1744-7348.1989.tb06785.x

Cited by 6 publications

References 9 publications

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Resistance to cane and foliar diseases in red raspberry (Rubus idaeus) and related species

Williamson¹,

Jennings

1992

Euphytica

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Several types of resistance to fungal pathogens of cane fruits have been identified by controlled infection procedures and incorporated into the UK Rubus breeding programme . These are reviewed with a description of the biology of the pathogens involved . Some of them take the form of a mechanical barrier associated with the position and rate of development of suberised periderms . For example, damage to the deep-seated cane polyderm occurs when Leptosphaeria coniothyrium (cane blight) infects the phloem and xylem, but forms of resistance which restrict the expansion of these vascular lesions have been found .Wound periderms, which form rapidly around natural splits in the primary cortex, play an important role in resistance of some genotypes to midge blight (Resseliella theobaldi and its associated fungal pathogens) .However, they are less effective against Elsinoe veneta (cane spot) which attacks canes early in cane differentiation before functional periderms have arisen . Other resistances are associated with distinctive morphological traits, most notably cane pubescence . This character is controlled by gene H and is associated with useful resistance to Botrytis cinerea (cane botrytis) and Didymella applanata (spur blight), but has the disadvantage that it is associated with increased susceptibility to E. veneta, Sphaerotheca macularis (powdery mildew) and Phragmidium rubi-idaei (raspberry yellow rust) . These associations present a dilemma for breeders, but other sources of resistance to these pathogens have been identified that are strong enough to overcome this disadvantage .From studies of inheritance it is concluded that a major gene determines one form of resistance to Phragmidium rubi-idaei and that three major genes determine resistance to S . macularis . Minor genes acting additively determine all the other resistances, though major genes may be involved in cane resistance to Botrytis cinerea and resistance to Elsinoe veneta, which were inherited without diminution over several generations . In two instances a common resistance to two diseases was discovered .

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