losing resistance???

Just going on from the ‘Going Native’ thread… if a rose is propagated for commercial release it is done so clonally, so how is that a rose can ‘lose’ resistance over time if each time it is propagated it is genetically indentical to the one from which it originated?

Mutations is the propagation material are further propagated. That is why you will sometimes see people looking for original bushes of some older roses. They want direct bud wood.

also the popululation dynmaics of the pathogen shift. a race that was once a very minor player in your environment has been able to reproduce and increase its percentage in the population.