Breeding with Alba-roses

Roses for Hybridizing
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21

Hi,

I am not sure if there is really something like BS “pressure”.

The idea behind this is that spores are more agressive in a region with a less amount of susceptible plants.

I haven´t seen any documents about scientific evidence of this idea.

?

More likely I follow the gene-for-gene-thesis.

This means a specific gene in BS is interacting with a specific gene in rosa.

In Europe, in 1990 scientists started collecting different BS races and they started describing different interactions between rose species and BS races.

Inoculating leaves with BS must be reproducible and therefore they invented the inoculating tower.

There had been about 8 different BS races in Germany in 1998 and they had different interactions with rose species.

In 2000 or so, scientists again started an european-wide collection of BS-races and I think, they are still working on this.

I dont´t know about any scientific BS resource sharing between U.S. and Europe.

On the other side, european rose breeders have trial fields in Europe and screening results and awards are usually valid for european regions.

If one reads about resistance of a specific variety in an european book, there is no chance to carry this forward to non-european regions.

Don´t forget that all those sources are from different times and BS strains have varied in time.

Back to the question,

I dont´t think that it is useful for amateur breeders to discuss BS resistance across the border.

And I hope we will never interchange BS races by sending plants across the border.

About Small Maiden´s Blush:

There is someone on the net who tells that there are two different cultivars, they have different prickles.

I have one from Sangerhausen.

If anyone is interested in photos, please let me know.

Rene

22

‘I am not sure if there is really something like BS “pressure”…’

There are conditions that favor BS development at some places such as the southern wet ones. As much as killing every HT in three years if unspraied (my experience most years here french Riviera as well as parts of US southern states)

More than probably related to temperature and splashing rain sequences. BS mutates quite often as examplified when introducing the more BS resistant vars. Here Baby Love was relatively BS free for two years as were Pretty Lady or KO. They are little healthier than average vars now.

A cool spring delays BS appearance.

When hot enough a rainy spell induces heavy BS damage that cannot be avoided by spraying.

Many species are immune as well as chinese vars.

Albas were not at all.

23

Mary,

I have cuttings from a R. rubiginosa individual (6x) which had been resistant to all known BS races in Germany in 1998.

Maybe this is interesting for you in breeding with Albas?

I took some hips last winter, should almost be selfings.

I am stratifying some for rootstocks.

There are lots of seed left …

René

24

‘When hot enough a rainy spell induces heavy BS damage that cannot be avoided by spraying.’

Pierre, I bought my sprays after reading this:

http://deposit.d-nb.de/cgi-bin/dokserv?idn=975616277&dok_var=d1&dok_ext=pdf&filename=975616277.pdf

After a year of training, in 2008 I had absolutely no problems with BS, even on zero-resistant varieties.

My goal is to get resistant hybrids by crossing resistant x non-resistant.

How can I get pollen or hips on non-resistant plants without spraying?

I became a professional sprayer and I hope, some day I will no longer need to do it.

René

25

Ren

26

There are tons of “feral” albas here in Beautiful Metropolitan Hygiene, Colorado. I have no idea what they are, but they’re everywhere. I’ve collected half a dozen or so and never had disease problems of any kind with them. (They also have fabulous fragrance and beautiful fall color.) One of them looks very like Felicite Parmentier, but I have no idea what it actually is.

Getting seeds from them has been another matter. This is the first year I’ve gotten any to sprout. I had been thinking that if one is looking for disease resistance, these roses may be the place to start, since they have grown wild from seed (after all, who’d plant a rose in a ditch a furlong away from the house?) any disease-susceptable ones would have died off.

27

Hi,

the seedlings of Scarborough X Small maiden