In Their Own Words: Oso Happy Rose Breeder David Zlesak

Rose Breeder David Zlesak
To celebrate National Rose Month, I reached out to one of the nicest and most gracious breeders we have the pleasure to work with. David Zlesak, a Wisconsin native, is the man behind Proven Winners' Oso Happy® series of roses. I just added all three varieties to my garden this spring, and they are bursting with clusters of dainty blooms. Pretty, long-blooming, and, of course, disease resistant, these roses are quickly becoming a favorite mine. Read on to explore their background and how David got his start. Happy Rose Month!
- Shannon

When I was 13, in 1984, I started breeding roses from a newspaper article in the Sunday gardening section of the Milwaukee Journal about Will Radler's rose breeding hobby. It was long before Knock Out came out. I loved gardening then, and the idea of plant breeding and coming up with new kinds of plants seemed wonderfully creative and fun. The mystery of each seedling being different and growing them out to find those that combine the strong points of the different parents with many surprises along the way really drew me in. I wrote to Will, and he connected me with a wonderful older gentleman that bred roses in West Bend, WI, the same town I lived in. Elton Strack became like a grandfather to me. I would visit him almost every week and really cherished our time together and what I learned.

I would save money as a kid throughout the year to buy new roses to use as parents. I would be taken in by the pretty pictures in catalogs and buy the ones that were gorgeous, but needed preventative spray and insulation to get through the winter. Elton focused more on his large-growing hardy species hybrids and some were a bit stingy in bloom. They were hardy though and always came through the winter and bloomed great. Even with spraying and insulating my more tender roses, I would lose many. I felt like if I just do what is written about to protect roses from what they needed protection from, things would be fine. Over time, feeling disappointed losing roses, I started valuing and understanding Elton's passion and use of the hardier roses, and began crossing them with the more tender ones to try to combine the best of both.

Oso Happy Candy Oh and Smoothie trace back to some parent lines that I selected when I was living in Rhinelander, Wisconsin. I germinated a lot of polyantha rose seedlings during those years, and in Northern WI in zone 3 many of them were not hardy enough. Thankfully, a handful of polyantha seedlings survived consistently. One was a thornless selection and others were thorny. The thornless selection was used with our native R. setigera over a few generations to eventually come up with Oso Happy Smoothie combining the near thornless stems and also the wonderful mounded characteristic of the bloom clusters and rich magenta/mauve highlights of the R. setigera parent. Candy Oh! is a cross of one of the hardy selections that was a light pink with darker pink edges with the classic rose 'Robin Hood'. Candy Oh! is darker than both parents and has the wonderfully vigorous growth habit of 'Robin Hood', but greater hardiness from the other parent.

Oso Happy Petit Pink comes from work I began in the late 1990's, wanting to combine the wonderfully floriferous habit of miniature roses (well branched, dense, lots of blooms) with hardier and healthier landscape roses like 'George Vancouver' (Canadian Explorer series) and 'Applejack' (Dr. Buck hybrid from Iowa State). I called Sequoia Nursery, which was started by Ralph Moore. He started his nursery in the late 1930's and made modern minis what they are today.  He is known as the "Father of the Miniature Rose." In the late 90's when I called, he was always very helpful, and I got four fertile miniatures that he recommended. Two of these are in the background of Petit Pink - Rise N Shine and Orange Honey. All these parents together made this wonderfully floriferous, mounded hardy, healthy mini. I love that it has a nice habit and the stems don't get too lanky. The cultivar name 'ZLEMarianneYoshida' is for my dear friend and landlady that let me have lights in the basement to start all my rose seedlings. She really liked that one too. Petit Pink is from a very different genetic background than the other two, but shares that mounded well-branched habit with lots of blooms.

I continue to love and work with polyantha roses because I love their habit and abundant blooming. I have worked with crossing them with typical shrub roses (there are some challenges in getting the crosses to take, but am making some progress). I especially am excited to keep working with the R. setigera lines as R. setigera has resistance to the disease rose rosette, which is lethal and becoming more common. I don't have rose rosette in my area thankfully, but would love to learn if Smoothie inherited this resistance or not. I have other seedlings and descendants of R. setigera I hope to have tested.

I have limited space resources, so I plant out typically a couple thousand seedlings each year and put them very close (8-10" apart). It encourages diseases to build. Many go down from disease, and then it is easier to see which ones show good resistance and then over winter. After a couple years, the well-adapted ones tend to shine compared to their neighbors. Some I hold back and use in more breeding because they don't have enough of all I'm hoping for. Others that seem to potentially fill a niche not well filled at the moment, I send to {Proven Winners ColorChoice} for trialing.

Since I started my love of plant breeding with roses, I still focus most heavily on the rose breeding. Breeding roses, all the wonderful people I've met, and things I've learned kept me inspired to pursue horticulture for my profession. I earned my BS in horticulture and then worked for the Forest Service and Hanson's Garden Village in Rhinelander, WI. Brent Hanson let me use land for my roses which was wonderful and is where I selected the hardy parents in Oso Happy Candy Oh! and Smoothie. I then went back to grad school in the Twin Cities for Plant Breeding and Molecular Genetics and worked on potatoes and then lilies, but my advisors always humored me and let me have some space and opportunity to do some rose projects. I then worked in Extension at the U of MN in Horticulture and worked to establish a northern branch of the Earth-Kind Rose Trialing Program in our region. I'm back at River Falls and work teaching to inspire the next generation of horticulturists. Some of the students help me with Earth-Kind rose plantings and work to understand the reproductive biology of our US native Rosa setigera, which may be a good source for bringing in rose rosette disease resistance to our modern roses.

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