Search found 396 matches

by david zlesak
Sat Feb 02, 2019 10:39 am
Forum: Rose Hybridizers Association Forum
Topic: Disease? recognize these spots?
Replies: 11
Views: 255

Re: Disease? recognize these spots?

They are sure small and blend in well. They scrape the lower sides of the leaves leaving a "window paning" effect. There are 3 species around here in the Twin Cities area. Two have just one cycle per year and after June the new growth is okay. The bristly rose sawfly/slug has multiple cycles per yea...
by david zlesak
Sun Jan 27, 2019 7:39 pm
Forum: Rose Hybridizers Association Forum
Topic: Variegated roses?
Replies: 35
Views: 2819

Re: Variegated roses?

Hi Stefan! :0) I'll do my best to keep it going and post some follow ups when it blooms. It has a flower bud set. A variegated Knock Out would sure be pretty with the nice otherwise dark leaves and richly colored flowers. This polyantha's mom is a single blush white. It would sure be fun to have a r...
by david zlesak
Sat Jan 26, 2019 5:45 pm
Forum: Rose Hybridizers Association Forum
Topic: Variegated roses?
Replies: 35
Views: 2819

Re: Variegated roses?

I love the look of the Fracis Meilland sport! With the edges being more consistently white, I wonder if it is a periclinal chimera with just the outermost layer of the growing point being mutated to not produce chlorophyll. I suspect mutated chloroplasts may be the reason for the attached variegated...
by david zlesak
Sat Jan 26, 2019 1:13 pm
Forum: Rose Hybridizers Association Forum
Topic: Some ploidy questions
Replies: 26
Views: 1073

Re: Some ploidy questions

Here is a paper that Dr. Kermani and her colleagues have reporting on chromosome doubling the triploid rose 'Iceberg'. The hexaploid interestingly is soft pink. http://www.irjabs.com/files_site/paperl ... 104925.pdf
by david zlesak
Fri Jan 25, 2019 10:40 am
Forum: Rose Hybridizers Association Forum
Topic: Some ploidy questions
Replies: 26
Views: 1073

Re: Some ploidy questions

Hi Matt! I like Karl's description. I've done a lot of doubling and also finding haploids in roses. The differences in thickness of plant parts, etc. due to ploidy exist, but need to be considered in reference to genetic background. For instance, diploid rugosa foliage is thicker and larger than bot...
by david zlesak
Sun Jan 20, 2019 3:25 pm
Forum: Rose Hybridizers Association Forum
Topic: Morden Series for health
Replies: 21
Views: 924

Re: Morden Series for health

I'm glad you are going to work with that Ark-op :0). I haven't had the opportunity to use it very much yet, but from my limited experience it is a little challenging to get seeds from either way and is a little better dad. I think it is a little finicky for the right combination that would take, jus...
by david zlesak
Thu Jan 17, 2019 10:56 pm
Forum: Rose Hybridizers Association Forum
Topic: Morden Series for health
Replies: 21
Views: 924

Re: Morden Series for health

I haven't seen rust on Ark-OP, but we don't typically have too much rust here. This one seems to be a hybrid with something neighboring (likely one of the Carefree BeautyTM seedlings growing nearby). It is an op of a stippled Rosa arkansana I dug up along the highway in Morris, MN.
by david zlesak
Mon Jan 14, 2019 10:23 am
Forum: Rose Hybridizers Association Forum
Topic: Rosa arvensis plena
Replies: 1
Views: 135

Rosa arvensis plena

Has anyone tried Rosa arvensis plena? http://www.helpmefind.com/gardening/l.php?l=2.5261&tab=1 Does it set hips? I love that R. arvenesis is reported to have shade tolerance (grows in forest understories) and downy mildew resistance. I've been having more trouble with downy mildew recently. It was r...
by david zlesak
Tue Jan 01, 2019 1:53 pm
Forum: Rose Hybridizers Association Forum
Topic: Do more richly colored seedlings have more richly colored blooms?
Replies: 16
Views: 1328

Do more richly colored seedlings have more richly colored blooms?

Over the years I assumed the seedlings with more reddish color early on would make darker colored flowers. I haven't followed any through to see if that truly is the case or not. Have others tested this? I potted up some reddish and more soft yellow seedlings separately from the same family and hope...
by david zlesak
Sat Dec 29, 2018 11:00 am
Forum: Rose Hybridizers Association Forum
Topic: Rebloom
Replies: 23
Views: 1209

Re: Rebloom

It sounds wonderful Kim! Hmmm. I studied Easter lilies for my doctorate and aspects of flowering was a part of my thesis. Temperatures below 70F can be perceived as chilling to Easter lilies, even though if the temperatures are below 50F the chilling hours (high 30's best) can speed along the chilli...
by david zlesak
Fri Dec 28, 2018 9:48 pm
Forum: Rose Hybridizers Association Forum
Topic: Rebloom
Replies: 23
Views: 1209

Re: Rebloom

Hi Kim! That's fascinating!! I wonder what environmental cues are allowing for the reliable rebloom. What an amazing climate you live in!
by david zlesak
Fri Dec 28, 2018 11:47 am
Forum: Rose Hybridizers Association Forum
Topic: Rebloom
Replies: 23
Views: 1209

Re: Rebloom

Here is a link to a pdf from a talk Fabrice and his group put together on this work. https://colloque.inra.fr/rgc8/content/d ... oucher.pdf
by david zlesak
Thu Dec 27, 2018 9:03 am
Forum: Rose Hybridizers Association Forum
Topic: THE ADAPTIVE POTENTIAL OF WILD ROSES AND THEIR PROSPECTS FOR ENRICHMENT OF DEGRADED AREAS
Replies: 1
Views: 107

Re: THE ADAPTIVE POTENTIAL OF WILD ROSES AND THEIR PROSPECTS FOR ENRICHMENT OF DEGRADED AREAS

Here's another article that is a little bit similar in describing situations where roses have been used to monitor/improve the environment. http://www.globalsciencebooks.info/Onli ... 2-165o.pdf
by david zlesak
Wed Dec 26, 2018 6:08 pm
Forum: Rose Hybridizers Association Forum
Topic: Rebloom
Replies: 23
Views: 1209

Re: Rebloom

Dr. Fabrice Foucher and his team have done a lot of great work understanding flowering in roses and also associated species like strawberries. Here is a link to one of their papers https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2011.04776.x There is a key general gene found in many plan...
by david zlesak
Mon Dec 24, 2018 2:09 pm
Forum: Rose Hybridizers Association Forum
Topic: Found two sets of twins yesterday
Replies: 3
Views: 231

Found two sets of twins yesterday

Yesterday I was potting up some early germinating polyanthas and am excited there were two sets of twins that shared the same testa (seed coat). Most of the time the smaller twin has half as many chromosomes as the main seedling and has the same genetic constitution as the originating unfertilized e...
by david zlesak
Wed Dec 19, 2018 10:14 am
Forum: Rose Hybridizers Association Forum
Topic: Flower bud differentation and growing in rosehip.
Replies: 14
Views: 474

Re: Flower bud differentation and growing in rosehip.

There is the nice paper by Dr. Andy Roberts and others from 1999 where they looked at the role of gibberellins on flowering in some roses. It seemed like that from their experiments that flower initiation in the roses they were working with occurred in very early spring as the roses were waking up a...
by david zlesak
Sat Dec 15, 2018 11:46 am
Forum: Rose Hybridizers Association Forum
Topic: PowerPoints from NCPN-Roses meetings from last summer are posted
Replies: 4
Views: 362

Re: PowerPoints from NCPN-Roses meetings from last summer are posted

Hi Henry, at the meeting the presentations helped to update the group on the progress being made in various projects and efforts related to roses and clean stock. There was discussion along the way after each talk with a short time for Q&A and then plenty of time over meals and breaks for people to ...
by david zlesak
Wed Dec 12, 2018 3:08 pm
Forum: Rose Hybridizers Association Forum
Topic: PowerPoints from NCPN-Roses meetings from last summer are posted
Replies: 4
Views: 362

PowerPoints from NCPN-Roses meetings from last summer are posted

Hi Everyone!! The PowerPoint presentations from last summers National Clean Plant Network-Roses meetings are now posted. Hopefully the pictures and outlines with bullet points of the talks will provide a pretty good idea of of the messages conveyed. The RRD material I think is especially valuable fo...
by david zlesak
Mon Dec 10, 2018 8:08 pm
Forum: Rose Hybridizers Association Forum
Topic: Polstjarnan (expanded)
Replies: 14
Views: 2979

Re: Polstjarnan (expanded)

Thank you Margit for asking. I'm excited for them to bloom next year. I was hoping there'd be a little blooming this past spring, but they must have been too small. They overwintered perfectly for our relatively harsh winter, which was promising. Most all of them had a lot of leaf spot or black spot...
by david zlesak
Fri Nov 23, 2018 12:20 am
Forum: Rose Hybridizers Association Forum
Topic: Rising-Star-Honoree-David-Zlesak
Replies: 23
Views: 1405

Re: Rising-Star-Honoree-David-Zlesak

That's a good question Don. We have characterized 13 different races, but there probably are a lot more. What makes a race is that the isolates comprising the race share a common set of virulence genes that can overcome the same host resistance genes. Of these 13 races, every rose we innoculated wit...