Desease resistance breeding

As it is no longer about what to do with discarded seedlings I start a new thread copying an earlier post.

I am breeding for no spray roses.

====It is an actual problem====.

Here french Riviera spring, summer or autumn early or late there is the possibility of splashing rain episodes. Some up to two week long. Some cold some warm. In bad years foliage is constantly spoiled by repeated episodes. Even the most carefull sprayers have a very hard time then.

Baby Love, Pretty Lady and Knock Out do spot then.

Modern roses show how every desease prone they are.

When many teas and ramblers are strong as trees… If not spraied most HTs or Fls vars decline in a few years with miserable performance. Even those generaly rated as healthy fail if without cooperative climate, tender loving care, ample isolation and good air circulation.

Here and in many other places and climates there are few as touchy garden plants as roses. Think to the ubiquitous Oleanders in our common (if probably not identical) z9!!..

====It is number one concern for roses breeders====.

Actually most gardeners do not intend to spray and within a few years in Europe at least most of the really effective chemicals will be banned from garden use.

This trend is going worldwide inevitably.

The crosses we are doing are aimed at finding a public ten years later.

Actually there is no better marketing argument than claiming for desease resistance. Flower Carpets and Knock Outs are bestsellers when they do not satisfy the traditional rose lover. No perfume and little grace.

I think as all professional do that breeding for the best desease resistance is just good enough and indispensable.

Every rose breeding team is hard working at new breeding pathes and revised strategies.

We are to cooperate toward this goal if we want to be game.

Friendly yours

Pierre Rutten

Jim Sproul (zone 9) replied on Mon, Jan 16, 2006

I very much appreciate your thoughts. It is true that greenhouse conditions are not the same as outdoor conditions.

When I first got my greenhouse, I brought in several very “clean” commercial roses (at least clean when grown outdoors!) These included ‘Sexy Rexy’ and ‘Singin’ in the Rain’ among others. However, in the greenhouse, they get powdery mildew since I do not spray in the greenhouse. In fact, I don’t do any spraying outside either.

I have found that seedlings that are completely clean of powdery mildew remain that way outdoors. Blackspot is much harder to predict since I do not get it in the greenhouse. I do however, let black spot infect my seedlings outdoors.

Two of my favorite parents are ones that you mentioned: ‘Baby Love’ and ‘Pretty Lady’.

I am with you that disease free roses are the best goal!

Jim Sproul


Just as Sunsprite, Sexy Rexy is a poor plant for me. Tried thrice before giving up as all dwindled.

Here open field, The MacCartney Rose does never mildew before summer. Much later than other roses such as the banksiae that do from early spring sprouting. Different vars and different strains.

When an initially resistant var is successfull; being widely grown increases the misfortunate probability of a new damageable desease strain appearing. Tropicana initialy was outstanding for dedease resistance. When widespred it became among the most succeptible.

Pierre Rutten

I have Sexy Rexy. It will blackspot here on the lower half of the plant(just like New Zealand and it’s descendant Octoberfest)just like clockwork with or without spraying every year. I definitely would not have it if there were any other compact pink floribundas that were decent (or not impossible to get like from Europe)for the spot in the formal garden it is in. That said, I have noted that it seems to pass on rain resistant petal qualities and have some itself.

Pretty Lady on the hand, has yet to show either bs or mildew. The only issue it seems to have for me is weak peduncles.

Ive never touched Knock Out or the Flower Carpet series. Theyre so bland and roses are about landscape aesthetics (to me). Even the massive Golden Wings is aesthetic in the proper landscape size. I bought Carefree Marvel this winter and planted it. It is derived from the Flower Carpet series but it’s foliage and blooms have far greater impact on a landscape than the Flower Carpet series. Beyond that, Flower Carpet Red, Sunshine, White and Coral will blackspot here. Pink and Appleblossom seem to be fine. The foliage alone can be as beautiful as Dortmunds is.

I think part of the popularity of Knockouts and Flower Carpets are the replacement of other landscape plants such as Azaleas (which require acidic soil and only bloom once per year). I see fewer and fewer commercial landscapes done with these types of evergreens and more and more done with these landscape roses.

For a year or a little more Pretty Lady and Baby Love were totaly healthy. Since then they spot a little with little rains. With heavy splashing rains there are spots on many to most leaves but less than on other vars and they recuperate and continue to build up. Better than Flower Carpets.

New Zeeland was an average often defoliated soon dwindling HT here. There are few roses in this class able to build up. This ability is my sorting feature: progenies are rarely better than the worse parent. Frederic Mistral, The McCartney Rose and Elina are a few HT that pass the test as do teas, noisettes, many ramblers and species hybrids.

Long splashing rain spells or hot wet weather are the most discriminating episodes. If not in a semi desertic environment even the carefully spraied roses are quite miserable then. Only decent modern roses are those remote from other roses and with macadam, paved, wall or gravel environment.

Pierre Rutten