Culling & Rugosas

A general question:

Would I be correct that a rugosa/rugosa-type rose(s) that were very healthy, but otherwise bloomed with single flowers in shades of pink or white, are probably not worth keeping? If it were double, or of an interesting color, then my opinion would be otherwise.

These were planted out late last summer, and have started blooming this spring.

Thanks,

Chris Mauchline

Hi Chris,

I feel as you do Chris that the chances of a cultivar that sells in large volumes of a single-flowered rugosa type would probably be low. It seems for straight rugosa types many nurseries are going with either old cultivars or ones like the Pavement series that were not patented. So, a new straight rugosa hybrid would probably have to be really unique and nice to carve a niche on the market. If you have a limited pool of very healthy rugosas with good plant habit and flower volume, some of your hybrids may be worth saving as parents. Double flowers (at least greater than 5-7 petals) is dominant, so in crosses with a double rose should produce at least some double-flowered seedlings. Congradulations on getting some nice healthy hybrids. Here in the Twin Cities we have gotten blackspot races that Hansa and many of the Pavement series are susceptible to. Maybe there will be room for new cultivars with similar plant habits and color as old standbys if they hold up better to disease.

Sincerely,

David

My ((Therese Bugnet X OP) X OP) X OP is a single; but it is very short (2 to 3 feet), one of my best bloomers, is very fertile even with tetraploid pollen, and the seeds germinate reasonably well. This is an example of a seedling with single flowers that I obviously feel has genes that I think are worth passing on.

A warning - rugosa “blood” seedlings have a tendency to sucker. I now put a screen around each of my rose seedlings made of plastic gutter guard (the screen is taged with the name of the crossing information). This way 2 - 3 years from now I will know if a plant is what I think it is. Even a map is of limited use when suckers are all over. I feel that I wasted many years of hybridizing because of this problem.

Henry,

Could you bud that rugosa on some other rootstock and hopefully eliminate the suckering?

I am interested in the properties of a seedling on its own roots (for northern climate considerations).

Thanks for the input! (If anyone else has thoughts, I’d still be interested in hearing.

As I pointed out, they were planted last fall. I planted all my roses (rugosa or not) at very small intervals. I should check my heritage (Thanks Henry! as I may have some cross I’m interested in.) But in general, though healthy, these plants aren’t all that interesting in flower, so I’m probably going to yank them soon as the rugosas are crowding out the other roses and don’t provide anything “new”.

Dave,

As a rose grower, I’m glad we don’t seem to have that blackspot race that attacks Hansa, but as a breeder, I won’t be able to select against that weakness.

Thanks again,

Chris Mauchline

SE PA, zone 6

The best RS for rugosas is R. rugosa alba.

Chris

May you tell us a little more about these “rugosa/rugosa-type rose(s) that were very healthy, but otherwise bloomed with single flowers in shades of pink or white”?

In my opinion there is room for different rugosas.

One may wonder at the fact many rugosa sold are seedlings.

Where were/are the hybridizers???

There are a lot of rugosa hybridizers. the problem is that rugosas are even numbered diploid, tetraploid, while most of the other fancier, modern roses are odd numbered polyploid. you do not always get chromasome “match-up”. the results, when the plants actually set seeds, are non-viable seedsand alot of lethal combinations. when the seeds of these crosses actually grow into plants that flower, It’s like there is too much information and they produce a very simple 5 or 10 petal rose. Other times the resulting plants are sterile and even missing some flower parts.

ron

I certainly with Pierre that “there is room for different rugosas.” And not just expanding the colour range but also developing different forms of shrubs. Especially dwarf ones. This will come about, of course, by mainly using species or near species in breeding programs with rugosas.

Rugosas can be worked with at the diploid or tetraploid level. Most of them, of course, are diploids. Th easiest way to bring rugosas up to the tetraploid level is by crossing with hexaploid species (Rosa acicularis, R. Moyesii, etc.). Regardless, there is generally no point in crossing rugosas with Floribundas or Hybrid Teas to develop rugosas, since the rugosa characteristics of the shub are lost when using these modern types of roses. Using species or near species retains the rugose foliage in a modified form.

There has been very little work crossing Rosa kordesii cultivars with rugosas, but I think there is potential for developing increased disease resistance by doing so. I would concentrate on using the Rosa kordesii L83, since it is fertile both ways and is quite hardy (Zone 3). I have one selection of ‘Hansa’ x L83 that hasn’t bloomed yet. The foliage is modified rugose and the shrub has a spreading habit.

I don’t believe there are “many” rugosa breeders. There are probably only a half dozen in Canada. But even though few in number, because of climate limitations for growing roses this country has always been and continues to be a world leader in developing rugosa cultivars.