American Rose Annual 1918 pp. 43-45.
Notes from the Rose Firing-Line
W. VAN FLEET
Department of Agriculture, Washington, D. C.
EDITOR'S NOTE.—Those who have followed Dr. Van Fleet's records and observations through the 1916 and 1917 Annuals will find encouragement in these notes. None of the other hybridizers are dealing, so far as we can ascertain, with the new species material received from China in the past six or eight years.
OUR rose-breeding work in 1917 consisted chiefly in developing the hybridizations effected in the spring of 1916 at Chico, Cal., and Glenn Dale, Md., and in making further combinations at the latter place between new hardy Chinese species and the finest modern show and garden varieties. Pollen from the extensive collections of the National Rose Test Garden at Arlington, Va., was freely used and with very apparent good results. The successful hybridizations, as judged by the sound fruits collected at the end of the season, numbered about 2,500. Several thousands of crossings on newly established species failed, but enough succeeded to represent nearly all combinations that appeared desirable at the time.
The seeds are principally grown in frames and beds under lath shade, and in the open air, retaining natural conditions so far as possible, but the results of certain of the more difficult crosses were planted in pots under glass. The tardy germination of many kinds of rose seeds is very trying. A small proportion of the seeds taken from the hips of Multiflora, Tea, and Wichuraiana varieties may promptly germinate when grown under favorable conditions, but rarely all. Many will be delayed until the following season, and others may not sprout until they have been in the soil several years. Seeds of the great majority of rose species, native and exotic, and their hybrids, consistently refuse to grow until the second year after planting, and individual seeds have been known to "hang fire" for as long as seven years, growing with full energy when they did start.
We find it advisable to keep all sowings of rare hybridized seeds in view for at least five years. Only those bearing labels previous to 1918 will be discarded the coming spring, and then only if careful examination fails to show sound seeds. At the head of the list for quick germination may be placed Rosa multiflora and at the end, R. laevigata, the Cherokee rose, seeds of which have never sprouted until the third year under any treatment we could devise. Seedlings require from one to four years of growth to show their full characteristics, though everblooming varieties often attempt to bloom within a few weeks after coming up.
These observations are made to explain in part the slow progress made in developing hybrids from the newly introduced Asiatic roses. Further delays are caused by the time—often three or four years—needed to establish the recent introductions and grow them to vigorous fruiting sizes, and also to propagate desirable hybrids when at last they have been obtained. Much time is also consumed in effecting certain crosses among annual bloomers where there is little apparent natural affinity. Certain crosses may fail in toto for several successive seasons, only to yield in the end to persistent effort, while other desired combinations are so difficult that the worker comes in the end to regard them as impossible under his working conditions.
Making all allowances for the difficulties and limitations of the work, we regard the hybrid rose seed crops of the past two seasons as the most promising yet harvested and trust that time will show this estimate is not an error.
As regards the character of the work, greatest efforts were expended on R. rugosa, R. Hugonis, R. pomifera, R. Wichuraiana, and R. bracteata, though more than twenty other native and exotic species have been interbred and crossed with practically all the best and newest garden roses of the hardier classes, including Hybrid Teas, Hybrid Perpetuals, and Hybrid Briers. Of the newer species, R. Soulieana shows best results, giving, in combination with R. Wichuraiana and the white-flowered form of R. lucida, single and double blooms of the most perfect finish and in boundless profusion on vigorous and healthy plants. R. Moyesii has shown that it can impart its striking deep red color to its hybrids, and some fine things may yet be developed. R. Hugonis still proves refractory, the hybrids losing yellow coloring to a great extent, but showing improvement in form and substance of bloom. Several hundreds of hybrids with other yellow roses, and thousands of chance or self-pollinated seedlings, are under way, and there is a possible prize among them. Harison's Yellow has yielded just two fairly vigorous plants out of the thousands of seeds sown the past seven years, and it is hoped that some light may eventually be shed on its parentage. We look for desirable everblooming garden types among the great number of Wichuraiana and Rugosa hybrids now in existence.