Talking of Rugosas. For me there are three distinct groups of Rugosas, and when I talk about disease-proof, I refer only to the first of these groups, and please, if your experience is different, believe me that this is my experience in Melbourne.
First group: R.rugosa, R.rugosa alba, Belle Poitevine, Blanc Double de Coubert, Delicata, Frau Dagmar Hartopp, Jens Munk, Max Graf, Nyveldt's White, Roseraie de l'Hay, Rugspin, Sarah Van Fleet, Scabrosa, Schneezwerg.
Second group (rugose foliage, but second class): Agnes, the Grootendorsts, Fimbriata, Lady Curzon, Martin Frobisher, Mme.Georges Bruant, R.x micrugosa, Schneelicht, Souvenir de Philemon Cochet.
Third group: Conrad Ferdinand Meyer, Mrs.Anthony Waterer, Nove Zembla, Rose a Parfum de l'Hay, Ruskin, Vanguard (BS magnet).
Given ideal conditions for growing, perhaps I am wrong to belittle some of these second and third groups, and they will perform better for some, but given some neglect, this is how I rate them. The blooms on all are fabulous, what better red than Mrs.Anthony Waterer, just a bit rust-prone. They are the most handsome of rose plants, IMHO!
Most of these better rugosas are available from Reliable Roses.
Sparaxis, could I suggest that you don't prune your Rugspin. Rugosas don't need pruning, and if yours is so small, then let it alone. Trying to grow amongst David Austin roses is quite a tall order, being crowded and all. Rugspin is a vigorous grower, and I can only suggest that it is sulking. But why prune it??
Here is a link that might be useful:
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Useful info
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