When Natives Attack (Plants that is...)

Recently, in helping to plan a garden at church I managed to horrify a friend of mine who is a gardener by suggesting that we could plant a native rose like Rosa virginica.

"Those are a vector for "rose rosette disease", she exclaimed. "You know what they have to do when an ornamental rose gets infected with that? Dig it up and burn it"

While I could definitely appreciate her comments as a fellow gardener, it left me wondering... Is it a wise policy to exterminate native species when they create a threat to introduced ones? After all, as it turns out, one of the species of rose that may be affected most by rose rosette disease is Multiflora Rose, a horribly invasive exotic (that nonetheless contributed genes to many of our cultivated roses.)

It's not just roses either, there have been campaigns to destroy every last American Current since they can be a disease vector for blister rust, a disease infecting white pines. Although white pines and currents (Ribes sp.) are both native, the disease was introduced from a European white pine. This has led to the peculiar situation where some species of American currents have the unusual status of being both endangered and listed as noxious weeds at the same time.

I've also heard of eastern red ceders being cut down across a wide area because they can infect apple trees (and I've seen the fungus on the cedar too, which looks like some kind of weird space alien).

So, what should we do when natives are capable of spreading diseases to other more commercially valuable plants? Would it be acceptable to let a species of American current go extinct in order to save white pines? What about eliminating native roses to avoid contamination of cultivated European ones? It's an interesting dilemma...

For now though, I'm going to keep my Rosa virginiana and my Rosa carolina. If they end up killing my grandmother's roses, then I suppose it's a sacrifice I'm willing to make (but maybe if I'm lucky I'll infect the multiflora rose creeping up the hillside towards our property...)