I am curious if multiflora is Black Spot resistance. I know that there is a problem with Mildew but I can’t find anything else.
Johannes
I have never seen BS on multiflora, either in KS or western PA. That accounts for only a few strains of BS of course.
I should add that I have a bunch of seedlings that came from Single Bliss. They look like multiflora in foliage, flower, and fruit but along with the repeat bloom they carry the BS susceptibility habit. They have survived several years crowded in a large pot. I collected all the fruits from one that grew about 18 inch tall raceme this past fall to use for germination testing. Now I have dozens of diverse sproutlings in a range of colors from white to deep pink, mostly single but some double. Most repeat vigorously but a fraction are tall growing and not yet in bloom. I don’t know if the repeat gene is from R multiflora nana or from other parent in the mini line of tetraplooids. I will screen these for resistance this summer.
I would not be surprised to find things that look like multiflora and are susceptible. R multiflora carnea, old rootstock type is totally resistant here. I think if BS got multiflora much, we wouldn’t have had people trying to use RRD as a biocontrol agent in Iowa and elsewhere.
Here’s a link to an old article I’d saved, that you might find relevant:
“Identification of molecular markers linked to Rdr1, a gene conferring resistance to blackspot in roses”
Too bad multiflora is SOOOOO susceptible to RRD or I’d be more inclined to use it myself.
I never saw any blackspot on multiflora in my central NJ property.
Cathy
Central NJ, zone 7a
I hope this link works better…
And the other article that I’d been thinking of was this one:
Theor Appl Genet (1998) 96 : 228-231
B. von Malek and T. Debener
“Genetic analysis of resistance to blackspot (Diplocarpon rosae) in tetraploid roses”
“The origin of the
resistant tetraploid breeding line 91/100-5 from 88/124-46 has been
described in Drewes-Alvarez (1992) and is depicted in Fig. 1. The
diploid hybrid 88/124-46 had been derived from a cross between
a tetraploid garden rose and a diploid Rosa multiflora followed by
four cycles of open pollination. The diploid status of 88/124-46 as
well as the tetraploid status of CT 40 and 91/100-5 was determined
cytologically by Drewes-Alvarez (1992). The resistant hybrid 91/100-
5 served as a parent for five different crosses (Table 1). As the parent
line CT40 as well as the progenitor 88/124-46 (Fig. 1) were both
resistant, whereas the present ‘Caramba’ is susceptible it was concluded
that resistance to blackspot in 91/100-5 was derived from
88/124-46 and probably originated in Rosa multiflora (Drewes-
Alvarez 1992; Debener et al. submitted).”
So, it sounds to me like this dominant blackspot resistance gene Rdr1 most likely has its origin in Rosa multiflora.
I agree with you. I’d love to try some of the smaller multifloras with my disease resistant hybrids but the RRD susceptibility scares me.
Rob
Sometimes I am so glad that I live in the north where many of these diseases like RRD vectors just don’t reach past the -35C or like we used to have -40C. But BS always a punishment eh, Terry R?
Multiflora has among the larger native natural dispersion with many different habitats forms. Only a few were introduced to Europa and America.
That it has one gene for Black Spot resistance implies it is confronted with this or a similar funghus.
One can also think there are other genes that could/should be searched as relying on a single gene for a vegetatively propagated plant is not a good thing.
Any Chinese listener?
Pierre I am not Chinese but I have been using R. forrestiana, R. setipoda, R. wilmottiae ,R. sweginzowii and R. davidii for a while now. I stated in earlier posts a few years ago here on RHA but there was a lack of interest so I never raised it again.
Warren
Please tell us about these species, Warren. My first question is are they hardy? -the never ending problem for me. I know that Rosa multiflora is much maligned but it will just survive for me in a protected spot. Such a dandelion.