Part 1: A passion for Rhododendron Hybridizing

Dr. Homer Salley

Danville, Kentucky
 

When Weldon Delp stopped making crosses in 1993 a long era had ended in the history of rhododendron hybridizing. Beginning in 1947 with the selfing of the hardy red hybrid, 'Dr. H. C. Dresselhuys, one seedling was selected from the many and later named 'Tower of Power. These dates, 1947-1993, mark the years of the beginning and ending of a career as a nurseryman that lasted 46 productive years.

Few nurserymen ever created so many or sold so few. Delps Crystalaire Rhododendron Foundation accepted gifts but did not sell plants. At one time Weldons mother, Christina Delp, sold a few unnamed seedlings, but she was discouraged in that practice. She was very pleased once when she got $20 for a plant, then found out later it was being saved for breeding purposes! Called '"Mama" by all the family and friends, Christina was a lovable, untiring, faithful greenhouse worker for many years. Seedlings from a cross had to have labels giving the parentage as identification. While writing out the cross (['Pygmalion x haematodes] x yakushimanum, Exbury form), she was inspired to use the name 'Weldy; that was a lot shorter. Mother Christina passed away in 1987, at the age of 87.

Weldons wife, Ginny Delp, did nearly all the naming after that; with her computer, beginning in 1985, she entered names, colors, parentage, foliage descriptions, sources of seed and pollen. "Coloring" meant using the color chart of the Royal Horticultural Society and selecting the correct color number for flower buds, and then the size, shape, and color of the fully opened trusses of flowers, all these requirements for the registration of named hybrids. (Hardiness ratings had to wait until field testing was done over a period of years.) Her own particular genius was the coining of names not previously in the International Rhododendron Register. Her accepted registered names now number 389: altogether she has originated 1,286 rhododendron names. These numbers must even challenge those of the prolific German hybridizer, Hans Hachmann. (See Delp hybrid registrations published in each Journal ARS, beginning in 1992. See also the annual supplements to the Register published by the Royal Horticultural Society, London.)

An Ohio nurseryman who has been growing Delp hybrids called to report an incident that occurred while on tour in Scotland. He had visited a nursery there where he was told that the Delp hybrids were ineligible for registration because of their lack of adequate testing. When the incident was described to the International Registrar, Dr. Alan Leslie, Royal Horticultural Society, Wisley, a reply was sent to the Ohio nurseryman. "I understand that you had been informed that many Delp hybrids were ineligible for registration having not been adequately tested. This is not true: for two reasons. Firstly a good number of them have been grown by other people in other areas. Secondly and more importantly this is not a condition or prerequisite for registration. It is of course highly desirable that raisers should seek to name (and then register) only the best and most distinctive new plants. And admittedly many growers do rush in breathless with excitement at their latest novelty which on mature reflection turns out to he no great improvement on others or hardly distinguishable. However, the point I want to make is that it is up to the originator to make the decision as to what is worth naming, not the International Registration Authority. We are there to deal with all cultivars that have been named; we do not sit in judgment over quality and distinctness, but provide a service in name regulation and, through eliciting data on parentage and characteristics, a reference for anyone interested. We strongly encourage testing and a conservative approach to naming but once a plant is named we want to know about it! If I can be of further assistance, please do not hesitate to contact me here at Wisley." One might wonder if the Registrar could have heard a recording of a Delp illustrated lecture, given before his hybrids had names, identified only by their parentage!

Weldon Delp did not really retire as a nurseryman in 1993, because he then started teaching his daughter, Joyce Harris, how to propagate cuttings of the many hundreds of his hybrid creations. In the same greenhouse in Harrisville, Pa., where the hybrids were born, the massive task has begun of producing for distribution small quantities of the huge number of named, registered hybrids and of those not yet registered.

A Canadian nurseryman came and placed a $3,000 order. The taking of scions for rooting required locating those plants that had been given over the years to many friends and growers. Who had which ones? What hybrids were known to have survived conditions in a variety of places around the United States and Canada? Ron Fleeger brought cuttings to Weldon from Paul James. And there are hundreds of plants in the back woods at Harrisville with an abundance of terminal shoots waiting to be snipped and stuck in the propagating bed.

Growing also in the greenhouse are 500 tiny seedlings Weldon started from seeds of a selfed, West Virginia maximum species called 'Green Max.* Some of the seeds were treated with colchicine to attempt an increase of plant chromosomes. Selections will be chosen after flowering next spring. So his breeding and growing still goes on in smaller ways.

The Great Lakes Chapter formed the Delp Study and Preservation Committee with funds to support a serious work. Questionnaires were sent and replies came back with listings of 810 different Delp hybrids that were still alive. Thirty-five locations reported: some had as few as one; some had as many as 25; some had up to 45, and one man, Paul James, had 391! Charles Dagnian, Colorado Springs, telephoned; one of his best rhododendrons, "Genevieve Schmidt, was doing well at elevation 7,1 00 feet! Another favorite of his was lepidote "Blue Rascal."

The Delp study has produced more data: of the total 810 hybrids located, less than half, 389, have been registered . Of the 33 locations reporting, the average collection has 43 different, named Delp hybrids. In the severe climate of the Delp homestead there now live 347, which is exceeded by the number grown by the supreme collector, Paul James, with 391. Names of hybrids now considered to be extinct: 'Aflame, 'Airwaves, 'Alyssa Ray, 'Apricot Sunset, 'Colorburst, 'Delps Celebrity, 'Heap Big Indian, 'Jennypoo'*, 'Leap Year, 'Magenta Madness 'Microflare'*, 'Tom Shirey. A list is available of 29 registered Delp hybrids believed to exist but not yet located. (Do you have unreported, named Delp hybrids?)

`The search for a well-endowed arboretum with a suitable location for a display garden of Delp hybrids ended when The Dawes Arboretum, Newark, Ohio, offered a formal agreement to the Delp committee. This garden began with a planting of 15 budded plants and a propagating bed with cuttings of many others. Director Donald Hendricks has requested the committee to send only named, registered plants. When asked how many rhododendrons the Arboretum could accommodate, his reply was "enough to color a landscape of 250 acres."

Tissue culture multiplication is being utilized with a very few plants: 'Angel Powder, 'Delps Sunsheen'*, 'Pana, 'Hindsight. Several others are being considered. Why had not distribution quickly followed the creation of new rhododendrons? Weldon was very skilled at propagation; however, his greater passion was hybridizing. With no thought of any financial return he often would spend $10,000 or more annually in the greenhouse. It was not physically possible to create a large number of new hybrids and at the same time do field testing by growing them on. He planted a few, gave away more than he kept. His talent was God-given, he felt, to create beautiful, hardy hybrids for the severe climate in west central Pennsylvania. If they would survive there in USDA Hardiness Zone 4, they should grow in a great many other places. The new hybrids not hardy there could serve gardeners in more moderate zones.

Weldons genius showed in his experimentation. Admirer George Gray said, "He carried his 'What if's to completion and was a source of new information. The completeness of his documentation in all phases of his hybridizing activities is extremely impressive. And his best qualities are his generosity and helpfulness." Consider the creation of hybrids 'No Way* and 'Ididit;* the former a cross between a lepidote and an elepidote done in collaboration with Dr. Doren Hinerman; a noted rhododendron geneticist said "no way" could such a cross be successful but rhododendron hybrid 'No Way still lives showing results can come from time consuming patience. The azaleodendron 'Ididit is an expression of satisfaction from crossing 'Caroline with two azaleas, an extra effort that few would spend the time doing when poor results are the usual rule.

Several of Weldons admirers have said his greatest creations are the triploid lepidotes ('Neat Feat, 'Has Pizzaz, etc.) which resulted from crosses of tetraploids with diploids. These lepidotes bloom early with the azaleas but are more hardy than evergreen azaleas. And you dont need to "dead head" them. They are sterile.

In cultural efforts two outstanding accomplishments are credited to Delp. In 1987 he announced the results of experimentation on the best method and timing for pinching to get maximum terminal shoots in order to avoid growing "leggy" rhododendrons) Also a notable feat was getting flowers from seed in 16-18 months. Flower buds can be set from seed in 14 months, then a month of cold treatment followed by a month of warming to open flowers. Toward the end of April the greenhouse is known as " place of great excitement, filled with glorious color from new hybrids flowering for the first time. Only about 2 percent of the seedlings are exceptional enough for Ginny to name and "color" them..

"If they are any good," Weldon would say, "the world wont let them die"--even if he did not grow them on for hardiness testing. For a while the late Bill Storms of State Road, NC., was that "world" trying to multiply and distribute. At one time the wrong rooting hormone caused the loss of a greenhouse filled with fresh cuttings. But Cardinal Nursery issued a sales catalog, and Bill gave Paul James a "backup" for nearly every Delp hybrid. But that is a story for another time--the world out there that would not let them die. Bill and Paul were only two of the apostles that spread the good news.
 
 

The information in this report and help in compiling it comes from the following: Everett Albyn, Allan Anderson, Virginia Delp, George Gray, John Heinze, Paul James, Jack Looye, Plant Name Registrar Jay Murray, Delp Study and Preservation Committee Chairman Dr. Tom Ring, Sally Salley and all who sent a list of Delp hybrids. The author kindly thanks these contributors.
 
 

1. Salley, H. E. The Children of 'R. 0. Delp. J. Amer. Rhod. Soc. 43: 1; 1989.

2. Salley, H. E.; Greer, H. Rhododendron Hybrids, A Guide To Their Origins. Portland, Oregon: Timber Press; 1986.

3. Salley, H. E.; Greer, H. Rhododendron Hybrids, Second Edition. Portland, Oregon: Timber Press; 1992.

4. Swanson, P. L. The continuing search for northern-hardy rhododendrons. Amer. Nurseryman; May 15, 1974.

5. West, F. H. Hybrids & hybridizers, rhododendrons and azaleas for eastern North America. Harrowood Book;1978.
 

Dr. Homer Salley is co-author of two editions of Rhododendron Hybrids and two volumes of Rhododendron and Azalea Research. He is president of his Bluegrass Chapter.
 

(Part 11 will more fully explore which Delp hybrids grow where with a close look at the collection of Paul lames Boones Mill, Va.)
 

1 "Pruning for Bushy Growth," Weldon Delp, J. Amer. Rhod. Soc. Vol. 41, No 3. p.137.
 

*Name not registered.

**Registration pending.
 
 
 
 
 

Part II: Collectors Save the Treasures
 

One of the greatest rhododendron collections in America surrounds the beautiful mountainside home of Paul and Barbara James. Under a light canopy of evergreen and deciduous trees the steep slopes have been landscaped with paths that wander about dense plantings of azaleas, lepidote and elepidote rhododendrons among the dogwood trees in a splendid display of color the last week of April and on into May. This enormous, wonderful garden is located southwest of Roanoke in Franklin County, Virginia, near the village of Boones Mill, but you wont find it without knowing where to look. It is guarded by three sleepy dogs; a fourth is very small but a good loud black barking alarm, named "Carcass"!

There are more young, different, named, rhododendron hybrids (385) there than at any other one location, except for the homestead which has 421. Paul is a supreme rhododendron collector; he has also organized a chapter of the Native Plant Society; he has made hiking trails up and into the surrounding mountain forests which have been permanently protected from development. It is no wonder that he turns down most invitations to leave home and go make speeches.

Paul talks of his very close friend, the late Bill Storms (Cardinal Nursery) of State Road, North Carolina, as a significant plant source. Paul purchased all the hybrids he could get from Bill. "Delps plants get better with age; when you live around them for a time, they become treasures," Paul said. He called Bill a generous man who, like Weldon , often gave away plants he could have sold. Bill later gave Paul many plants (as a back-up) in their original containers. Some were Delps or the Haags or Dr. Tom Rings and had been in their containers too long. Paul nursed them back to new life and planted them out. He found that Haag and hybrids made happy growing companions. Weldon Delp gave his plants and many cuttings of plants to Bill Storms for propagation and distribution. A catalog was published in 1988. As a nurseryman Bill Storms suffered two major disasters: 1) a major flood which floated off hundreds of containers filled with bark chips as growing media. 2) a storm of heavy, wet snow that broke in the roofs of his greenhouses. Cardinal Nursery was closed in 1993.

But Paul James collection of hybrids is second in numbers only to that of Weldon, their creator (see box "Ten Highest Collectors of Hybrids"). The most beautiful hybrid in flower the day of my visit was the dark red 'Tim Craig'*shown above in color. Rhododendron lovers everywhere will forever feel an appreciation for the friendship of Bill Storms and Paul James. Pause here and think about the philosophy of sharing with others as did Weldon and Bill and now Paul who gives back to Weldon cuttings for propagation of hybrids Weldon created but had lost. In Pauls collection there are now 201 named hybrids that are not known to be in existence any other place. Also there are many unnamed seedlings (with parentage records) growing and flowering which some day may be named and registered as Delp/James hybrids,

Much of what is described above also exists, perhaps on a smaller scale, at many other locations. There are collectors and creators of new rhododendrons who enjoy giving and receiving pollen, cuttings, and seedlings (as well as ideas) as Weldon Delp has done for over 40 years.. Most all have a collection of hybrids that may include a few sole survivors not reported by any others. To name Just a few: Allan Anderson, Franklin Lakes, N.J.; Bob Blough, Johnstown, Pa.; George Gray, Williams Bay, Wis.: Bob Grenkowitz, Romeo, Mich.; Velma Haag, Brevard, N.C.; John Heinze, Toledo, Ohio; Jack Looye, St. Catharines, Ontario; George Ring, Bent Mountain, Va.; Dr. Tom Ring, Bellaire, Ohio; Chris Trautmann, Cincinnati, Ohio; John Weagle, Halifax, Nova Scotia.

One happy grower of Delps lepidotes indicated he was not interested in Delps elepidote hybrids as they were quite complex and untested outside. "There are far too many hybrids named after every dog, cat, and wife in the U.S.A. and most to pass into deserved oblivion," he said. But hybrids havent yet gone into oblivion. We now have located 741 different, named plants still growing. Less than half, 301, have had registrations published or pending at this time. Only 37 registered hybrids are either dead or not yet located.

Weldon s reply explained the reason for the use of so many names. To quote Weldon: "Let me clarify the use of names for most plants produced.. When they are to be used in further breeding it becomes necessary to put names on them in order to avoid writing long parentages for all tags and in the countless computer entries. I grew thousands of seedlings every year and only the best are named to be used in further breeding, but there are many of these. Numbers are too easily transposed so not the safest method to use. I have been registering names of plants that I dont consider superior because Jay Murray and Dr. Alan Leslie requested that I do so. They feel that if it is to be used in further breeding, it is essential to have a record of it" (see box "Registrations of Raised Hybrids Published or Pending).

Weldon also stated, "I am only involved in the research and development of rhododendrons and azaleas to be introduced into the trade by retail nurseries. I do not retail, but I do give away many plants for testing."

This author agrees about parentage often being complex. As an example see the complete parentage diagram of 'Go Green that survives in Weldon s "back woods" where it gets very cold. In the winter of 1993-94 the temperature was down to -38°F at Harrisville, Pa. (see box "Go Green Parentage," page 1 26).

Many very complex hybrids such as this have the potential for great variation in offspring. In this instance there could be germ plasm of 21 different hybrids containing ancestors of 11 different species. Siblings have more possibilities for being very much more unlike each other, but in the case of 'Go Green Delps records show no other surviving offspring from the cross ('Ivory Palace x 'Silvery Moon'*). Nature sometimes makes complex hybrids but not quite as involved as the modern ones created by such breeders as Delp. Further crossing of 'Go Green with another similarly complex hybrid such as 'Alley Oops (Tom Ring cross) could possibly create even more variability. (Printing on one page the complete genealogy of such a cross would present a real challenge for the typesetter!)

The reader may recall seeing hybrids listed by grex in Rhododendron Hybrids, Second Edition, 1992. Some named siblings are considered lost. Now with Ginny Delps computer records and recently compiled information by the Search and Preservation Committee of the Great Lakes Chapter we have a database of all 443 elepidote crosses and their surviving offspring. Siblings having the same parents and similar genetic heritage tend to have similar but not identical traits such as hardiness, color, season of flowering and ease of rooting. Each grex is numbered and each named member of the grex has the same number. For example, this entry shows that three named plants belong to grex No. 150:

150) ('Goody Goody x self) = 'Color Purple'*, 'Picturesque'*, 'Testy'* (see photo of 'Testy on page 123).

All three of the offspring carry the grex number 150.

The 32-page list is available from the author (see Notes at end of article).

Published color illustrations with this story show grex numbers, and if there are siblings of those shown they also are listed with that grex under the photo.

A brief note here to recall the role of the well-endowed Dawes Arboretum at Newark, Ohio, that has welcomed the registered Delp cultivars into its collection of plant material to be viewed by the public with no admission charge. The director, Donald Hendricks, considers it a role of the Arboretum to fulfill an institutional purpose in this manner, and the number of mostly small cultivars donated there now has grown from 1 8 in September 1 994, to 193 in May 1995.

One aspect of Delps work that has been of interest to others is his program that brings rhododendron seedlings into bloom in about 14 months. One year after germination and their fifth new shoot with flower buds set, the seedlings are outside in the natural cold through October for hardening-off, then back inside for greenhouse warming and early spring flowering..
 
 
 

Acknowledgments

The author wishes to acknowledge with appreciation those who contributed to this report: Virginia and Weldon ; Paul James; Registrar Jay Murray; and Editor Sonja Nelson.
 
 
 

Additional Information

A number of lists detailing Weldon s hybridizing are available. They are: 

• Delps Most Prolific Seed Parents & No. of Surviving Offspring.

• Number of Raised Elepidotes from Crosses by Delp and Others With Their Surviving Named Seedlings.

• Elepidote Rhododendron Crosses by Others With Surviving Offspring.

• Delps Lepidotes: Names and Grex Numbers.
 

Copies of the lists are available from the author for $5 (cost of mailing and copying). Write Dr. Homer Salley, 136 E. Mason Ave., Danville, KY 40422.
 
 
 

Dr. Homer Salley, president of the Bluegrass Chapter, co-authored Rhododendron Hybrids and this year received the Gold Medal from the Society for his many contributions.
 

* Name unregistered.
 
 

Weldon Delp 421 

Paul James 385

Allan Anderson 92

Dr. Tom Ring 76

George Gray 49

Jack Looye 46

Chris Trautmann 46

Everett Albyn 45

Dr. Jean Beutler 39

Henry Wrightington 39
 

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