These leaves are not just thin or slim, they are anorexic.
Jackie,
Last year you sent me three or four of your R. foliolosa X Henry Hudson seedlings and I can confirm that one of them has this appearance too. So I think we can rule out herbicide damage (none used anywhere near me). I was thinking it was either malnutrition or RRD so I pruned the “bad” spots down to the earlier spring growth which appeared normal and amended the soil in the pot. Current new growth is appearing to be the same narrow, distorted foliage so I don’t think it is a nutrient deficiency. With your report on what you are seeing, I am highly doubting it is RRD because what are the chances of my seedling being affected as well when we are half a country away. The only way this could be accomplished is if the seedlings were infected before June of last year and then laid dormant for a year. So I would say that it just might be “foliolosa Seedling Syndrome.” The other thought I had was it might be heat induced (opposite of RMV) because the spring growth was normal and this appeared after the heat turned up. We have had a few weeks of cooler weather and I don’t see much difference so this most likely isn’t the case - it might need more than a few weeks of s lightly cooler weather though. I am going to hold onto mine for another year I think to see what it does and test a few theories with it. No other rose is showing symptoms and the other R. foliolosa X Henry Hudson are looking really good right now.
Just my thoughts.
Andre,
That is very interesting and somewhat confirms most of what you list-not RRD, not malnutrition, not herbicide (not used here either and neighbors not close enough) and if it was heat induced why don’t all of them succumb? or at least show some symptoms? Pierres’ experience of it being some syndrome unique to foliolosa sounds more likely with this info. Since only my foliolosa crosses with Henry Hudson are affected, maybe unique to foliolosa x rugosa? Interestingly enough, the first (and most seriously affected/infected) one has new shoots/suckers developing and they are even worse looking than the tips shown in the picture I posted. I have removed and isolated them and will continue to watch and see what develops. If it was really contagious I would think more would be showing symptoms because the first one was in a really packed situation. But on the other hand the other 3 were very close to each other and I do not know which of these were from the same hip(s).
These “foliolosa Seedling Syndrom” do grow on with distorted flowers and little fertility. Surviving as well as others.
More frequent among foliolosa seedlings but not unique to them.
A similar habit one can see looking at old “Watsoniana” multiflora.
This later syndrom is transmissible ( by pruning or root graft?) as I saw it was along a row in a roses vars collection.
Among my yearly seedlings I get a few with distorted and narrow parts that I throw away. Eventually similar to the dwarf Andy got.
Genetical mismatch or virus or viruses combined effects with differential expression eventually seed transmitted are some uneducated hypothesis.