Proceedings Library

In chemistry, for instance, water has the formula of H₂O. If

I am going to use for this purpose the U. S. Department of Agriculture Plant Hardiness Zone Map, prepared by Henry Skinner, which is much better and more accurate than the old map. We will have a quick look at novelties, all new rhododendrons introduced in the East within the last couple of years which are suitable for each of the principal hardiness zones in the principal parts of the United States starting at the Middle East climate and working up to the most severe.

Beginning with the Dexter hybrids, we will show a number of them. (Slides of

The cuttings for this test were taken from a plant of Cephalotaxus species growing on the grounds of the Sarah P. Duke Gardens at Durham, North Carolina. This plant is probably thirty or forty years old. It is about eight feet tall and six feet in diameter. Its main mass is stiffly erect with comparatively large, coarse branches. It would be generally unsuitable for the home grounds unless the home grounds were very large, but nonetheless, it has a place in a garden such as the garden which I am describing.

Very near the base it has developed a large fan-shaped spray of softer foliage with branches suggestive of a spreading Taxus species. This fan-shaped spray is probably five feet in circumference, and is readily traced to a single point on one of the main erect stems. It has probably developed within the last ten or fifteen

Plastic Bags: A number of workers methods have shown that plastics can be used for propagating softwood cuttings. Among these Nichols (1958) showed that, in Trinidad, softwood cuttings of cacao could be rooted successfully in plastic bags. This prompted us to investigate the use of plastic bags in British North Borneo. Our investigations showed that plastic bags could be used successfully for propagating leafy semi hardwood cuttings from 96 different tropical arborials. Some of the more difficult rooting species rooted included: Mangifers indica, Hevea brasiliensis, Achras sapota, Lansium domesticum, Eucalyptus deglupta, Psidium guajava, Nephelium lappaceum, Artocarpus integra, Annona squamosa, Tamarindus indica, Cinnamonum

Most people are aware that many new chemicals have been introduced in this field of plant growth regulators during the past twenty years. What is perhaps not too familiar to many are the methods used by industry to find these compounds. The remainder of this paper describes a method used by the author's company in its research toward finding useful chemicals in the plant growth regulator field.

This method involves three steps: 1) primary screening, 2) secondary screening, 3) field

I think I should mention at the start that I want to give credit to Dr. Reisch, who supervised much of this problem, and to Donald Kling, who carried out many of the actual experiments.

The purpose of the experiment was to determine the effect of wounding and the use of synthetic growth substances on callus formation and on root formation on Ilex opaca, and perhaps more important, to study the anatomy of the origin of callus and adventitious roots.

I am sure that most of you are familiar with the literature that would indicate that wounding of cuttings of Ilex opaca have resulted in stimulation of root formation and also the fact that use of synthetic growth substances have also resulted in increased root formation. Some of the literature would indicate that wounding was perhaps

In commercial production costly operations and organic matter must be recognized and reconciled with. Young plants either seedlings or cuttings, in their first and/or second year present no great problem nor cost, when grown in beds containing up to 50% peat. It's in the field product with plants in their second, third, fourth years that the organic matter requirement becomes a costly production problem.

Large quantities of organic matter added to mineral soils in an overall application is costly. Small quantities of fibrous peat to create an organic pocket for planting presents a costly operation if a uniform pocket mixture is to be created. It is here that the pocket mixer comes into play.

To make use of the pocket mixer for ericaceous plants, the mineral soil is first deeply tilled with a rotating tiller. One large shovelful of soil is

Propagation by seed is the usual method as the species is generally homogeneous and there is little variation among seedling trees. Fordham (3) states that a soak of 1 hour in concentrated sulfuric acid and immediate sowing of the seed resulted in germination within 13 days. The U.S. Forest Service (6) reports that 1 hour in sulfuric acid followed by stratification at 41° F for 90 days gave the best germination.

The usual plant forms, such as prostrate, globe, spreading, dwarf umbrella-like, columnar, pyramidal, weeping, and colored foliage are found in about a dozen species. Occasionally a new plant is found.

There are four very excellent books on conifers. One is by Murray Hornibrook: DWARF AND SLOW GROWING CONIFERS, published in London in 1923. This book lists and describes many forms that were found in Europe and now do not exist or, because of quarantine regulations, were never brought to this country. Another equally fine book is L. H. Bailey's CULTIVATED EVERGREENS,

Rhododendron japonicum inhabits the grass and scrub-wooded moorlands of Japan, including Kyushu, Shikoku, and Honshu. It does not occur naturally on Hokkaido although plants said to have escaped from cultivation are scattered in the hills around the city of

The story very briefly is this: I go every summer to a little island off the coast of Maine for a holiday, called Monhegan Island. This last summer I met the man who does these paintings. He is a Dutchman with the unique name of Tecco Slagboom, a most charming and unassuming man, who lives for the most part of the year on the island in a little home way off from the crowd. He produces paintings of all kinds, but I was particularly taken with the clarity and fidelity of the botanical part of his drawings. I thought that in these days of mass production and kodochromes it was rather pleasant to see craftsmanship of rather a high order, and so I asked him if he would make three drawings

As Sidney noted last year, a great problem in cutting experiments with Sciadopitys is the very limited amount of wood available. Unlike working with Junipers or Taxus you cannot set up experiments with hundreds of cuttings for each treatment, and hence the results in this report must be viewed with some scepticism as

The ridge, sash bar-rafters, eave and sill plates are home-made from rough cut redwood bench lumber. The lower section on the sides and end are enclosed with Johns Manville ¼" asbestos wallboard.

Four mil polyethylene is attached to 4 ft. wide sash. The sash is portable, made of fir 2 × 2's, treated with copper naphthalate, and covered with two layers of plastic with 1–5/8" dead air space between layers. The plastic is held in place with thin strips of redwood and tacker staples. The house is readily ventilated by the sliding sash.

A feature of the house is an upper and lower five foot wide center bed. The lower bed is for summer propagation, using either the vaporproof chamber or the mist system. The upper level is used for winter propagation.

The house is heated by

Although getting plants to grow tall in a relatively short period of time has its value, there are many other purposes for which photoperiodic treatment can be applied. By using long or short day-lengths we can control growth of many, but certainly not all, trees and shrubs. Actually it is a tool that we can use to our advantage under various circumstances.

Before suggesting any of its applications there are several facts that I would like to discuss concerning the response of a plant to photoperiodic treatment.

First, many people confuse photoperiod with photosynthesis, the manufacture of sugar by the leaves in the presence of light. The production of sugars by the leaves requires a relatively high intensity of light in

These abnormal growths are caused by fungi, rust, Black Mildew, virus mites, and other organisms. They have been reported from a large number of trees, shrubs, conifers, and herbaceous plants.

Dr. Henry Teuscher of Montreal Botanic Garden reported to the International Dendrology Union 1953 that some of these witches' brooms are caused by disease or insects, while others may be a bud sport. Teuscher reported that the witches'-brooms cannot be propagated by cuttings but must be grafted. He also reported that abnormal growths arising as a side shoot on a normal tree are the result of bud sporting and that they can be readily propagated from

The dormant one-year old stock plants are potted a period of several weeks to spread out the work load to alleviate the demand for growing space, and ease somewhat the demand for rooting space during the early spring season. We try to time the production of cuttings so that only about 20% of the total production occupies heated space in the early spring, with the greater proportion of the clematis production scheduled for the early and mid summer

Equipment

As usual, we were trying to test a number of things at the same time - a mistake, I believe, because one can become so confused in the multiplicity of tests that it is difficult to sort things out - but

For the benefit of those members and guests who don't know Helleborus (also called Christmas Rose), I would like to tell you a little about this particular plant regarding its likes and dislikes so that you will understand more readily how we try to apply its proper environments to the propagation of this particular plant in order to grow it successfully.

To begin with, I would like you to understand that Helleborus is a perennial and because it is called Christmas Rose, it is not a rosebush as some people think.

We all know that Helleborus is a rather temperamental plant, but it is not too bad once you understand the plant. Helleborus is perfectly hardy as it originated from the Alps in Europe. It will never get winterkilled as it does not mind low temperatures at all but it might get summer-killed, as

What I would like to do is discuss with you some of the experiments that you have been continuing along the same lines that I was working on in 1958. I have been concerned with working on some of the factors that control rooting. A plant very easy to root is Lombardy Poplar. The first question to ask is, why is the Lombardy Poplar so easy to root? The answer is a very simple one - it is very easy to root because the roots are already present in the tree at the time that you go out to take your cuttings. The root primordia in the poplars and in many of the willows are laid down as a normal feature of development of these particular plants and so they are already in the tree. All we have to do, then, is concern ourselves with what regulates the

I would like to go over a number of pine varieties grown in the northern part of the United States, beginning with Pinus sylvestris or Scotch Pine. Native in Europe to western and northern Asia, seeds from Spain and France have proven to be the best suitable strains for Christmas trees and ornamental purpose with good color and straight stems. Both strains are considered short needle pines. We also collect some seed in upper New York State, which is faster growing and with much longer needles.

Pinus strobus (White Pine) natural range from New Foundland to Manitoba south to Georgia, Illinois and Iowa, seeds from the lake states and upper New York are considered the best.

Pinus ponderosa, range from British Columbia, south to Mexico and east to Nebraska, Colorado and western Texas. We think seeds from the eastern rockies are the best.

Pinus mugo mughus (Mugho Pine) central and southern Europe seeds preferable from the Swiss Alps region.

Pinus nigra (Austrian Pine) central and

L. H. Bailey (1) makes some interesting observations on the etymology of the word greenhouse and on the history of greenhouse construction and use. Dr. Bailey notes that the original meaning of the word was simply "a house in which to keep plants green during the winter." The plants were not expected to grow in these original "greenhouses" which may have started as a glass-walled portion of a dwelling. Ultimately separate

I would propose that we discuss the topic of Dwarfing In Ornamental Plants under the general headings of:

1. History of Dwarfs
2. The advantages and disadvantages of dwarf ornamentals
3. Sources for dwarfing components
4. Methods of

The leaves of all plants treated with growth-retarding chemicals are much darker green than those of untreated plants. This color is related more to the action of the growth regulator than to mineral nutrition.

Three chemicals have been extensively tested on many kinds of plants (2). These are Amo-1618 (4-hydroxy-5-isopropyl-2-methylphenyl trimethyl ammonium chloride, 1-piperidine carboxylate), phosfon (tributy1,2,4-dichlorobenzyl phosphonium chloride), and CCC (2-chloroethyltrimethyl ammonium chloride). The growth of most plants may be controlled by the proper selection of one of these chemicals. None of the

This subject, growth regulators, is a very timely one. It was, in fact, a timely subject 25 years ago when IAA was isolated from urine and found to be useful in rooting cuttings. It was even a timely subject long before that when sugar and oxidizing agents were being investigated as rooting aids. It will no doubt be a timely subject 50 years from now, even though plants will have yielded up more secrets about themselves than we presently know. Perhaps, thinking of it in this way, Growth Regulators in Relation to Plant Propagation should better be described as a timeless subject.

At the present time we are probably on the threshold of propagation discoveries nearly equaling the period of the mid-thirties. Perhaps this evening we will catch a glimpse of what is currently going on in propagation as well as what the future may hold

We will discuss what they are, how they regulate the plant's physiology, and to what practical uses they have been put.

During the past few years in California, a definite need for clonal rootstocks, and rapid methods of propagating them, has arisen in several tree fruit species.

As a rootstock for the English walnut, Paradox walnut seedlings (Juglans hindsii × J. regia), resulting from natural crossing, have proved to be excellent, better in many instances than the usual J. hindsii seedlings. However, certain Paradox seedlings are far superior to others in vigor, resistance to nematodes, and to oak-root fungus. A method of developing clonal rootstocks from these certain seedlings would be of great

The wheat grain in germinating, releases an auxin, thus stimulating root growth. Auxin is another term for natural hormone produced by plants. Growth regulators as we know them today are synthetic auxins, with a purpose in mind, "to stimulate root growth".

Although auxins, or hormones, play a very important role in propagation today, there are many other factors equally, if not more important. In the preface of the University of California Manual 23, edited by Dr. Ken Baker, is a symbol of the U. C. System. Within this symbol, with a few minor changes, lies the identical basic rules of plant propagation. The changes are:

Dr. Alley has informed us of the development and importance of registration and certification of plant material, and I would like to review with you what we are doing with this material, how we maintain such plants, and the inspection of these Increase Blocks and last of all, the very important point, the acceptance of such nursery stock by the commercial

The International Code provides the guide lines for the correct naming of plants and sets a standard for the industry, as well as for regulatory agencies in enforcing laws pertaining to plant names.

Through need and experience, most industries have established standards for the products they handle. These standards may be voluntary on the part of industry members or may be established by law. When legalized it helps eliminate unfair competition. A

Pines are often propagated by grafting, and with considerably more success than by rooting. Grafting, however, has some drawbacks that would make rooting, when perfected, more desirable. Sometimes stock and scion, are incompatible. If a tree's superiority is due to its root system, this superiority will be masked when the scion is grafted to the rootstock of an ordinary tree. A reasonably successful technique should make rooting cheaper than grafting.

The following techniques are the ones found most successful with loblolly pine (Pinus taeda L.) after seven years of research involving trials with more than 15,000 cuttings.

The

The naming of a few plants in a local region, however, is quite different from the situation which exists today when we are dealing with many thousands of plants on a world-wide basis. There are probably between 200,000 and 300,000 species of ferns and seed plants known today. These are contained within about 10,000 genera and 300 families. Of these 200,000 to 300,000 known species, about one-tenth or 20,000 to 30,000 species, are cultivated. I have not located exact figures but Hortus II, published in 1941, lists over 18,000 species cultivated in North America.

The naming of cultivated

The prosperity and success of the citrus industry, and the financial solvency of individual growers, depends in no small measure upon the integrity, the knowledge, and the sound judgment of the nurseryman.

During the last three years over 5 ½ million citrus trees have been grown for planting in the commercial orchards of California. Every one of these nursery trees consisted of two parts, scion and rootstock. The scion variety was chosen first for the variety - such as orange, lemon, tangerine, or grapefruit, and secondly, as a particular

We shall treat four main subjects in our discussions of light. These are:

1. Light and seed germination.
2. Effects of light on stock plants for cuttings.
3. Light and the rooting of cuttings

Some parts of coastal Southern California are noted for relatively mild spring and autumn temperatures, perhaps suitable for optimum plant growth and generally considered to have a growing season of 250–300 days (9). Optimum day lengths , however, prevail for no more than 90–120 days of that period; indeed, most species make the major portion of growth during late May to early September. Thus, it might be expected that supplemental lighting that creates summertime (greater than 14 hours) day lengths throughout the "growing season" might have great value in promoting the growth of nursery plants--perhaps to the extent of doubling the growth per year of many species.

In our initial experiments at and around the University of California at Los Angeles, these exciting

There are statements in the literature that mention was made of the beneficial effects of darkness on rooting of apples as early as 1537 (2). Since that time there have been several papers describing the use of this technique for rooting cuttings of several different kinds of plants. Plants vary widely as to their ability to produce root initials when exposed to light. Many plants, of course, must be not at all, or only slightly, inhibited by light in the

Recent studies at UCLA indicate that the disease is caused by strains of the cucumber mosaic virus (CMV), and that the widespread occurrence of the disease is probably due to propagation of diseased cuttings from infected plants. Shoots free of CMV were rather readily produced by growing diseased plants at temperatures averaging 90°F for 3 to 12 weeks. Symptom-free shoots were removed from diseased plants, and were

Fortunately, my prepared remarks seem to be still appropriate. I feel that a tremendous volume of fundamental information has been presented at this Conference. If all of this information is

A few more years experience with mist propagation and some new additions in the field of root inducers and inhibitors and all of us old grafters are going to be without a trade.

There is only one reason for producing Pine Selections by grafting; up to this time no better or cheaper method has been found. What are some of the Pines reproduced by grafting? All of the selections of White Pine, the fastigiate, the pendulous, the globe and dwarf form, the various selections of Scotch Pine and also Swiss Stone Pine. This last Pine can be grown from seed, however, it is a very slow process and the variation in the seedlings is considerable.

The various Pine Selections that are being grafted today are either sports which are quite common among seedlings or the result of

This juniper is one of the best low-growing ground covers for sea shore or dry, sandy situations in the coastal areas. It will with-stand salt water spray, and even some submersion, exceedingly well. It also has been used quite extensively the past few years in rock gardens and mound plantings. The Shore juniper grows best in full sun and withstands most coastal and inland weather conditions. Through our past experience, however, we have discovered that it will not grow in the hot desert areas of our state.

In the propagation of Juniperus conferta in Southern California, we have found that cuttings taken from the middle of December to the middle of January root much faster and in higher

This clone grows about 2–3 feet in height and spreads as much as 8 feet. If planted on level ground, the plant will reach its greatest height at the center, and the side branches gradually slope toward the perimeter of the plant, almost describing a circle. If planted on a slope, the branches will follow the structure of the terrain, often exceeding 10 feet in spread but not more than 12" to 16" in height.

The color of the flower is a deep blue, surpassing by far the flower quality of Ceanothus horizontalis, ‘Hurricane Point’. The blooming period extends from March to May. Ceanothus ‘Yankee Point’ tolerates a wide range of environments. A sandy loam soil with good drainage and, in the inland areas, partial shade provide good garden growing conditions.

Hormone: Hormodin No. 2 - we have had very good results with this. The media is 3 parts Sponge Rok, one part peat moss mixed with water in a tub. The media is packed around the edges of the flat and leveled off. The cuttings are placed in intermittent mist house. Our largest house is 100 feet long, with a capacity of 150,000 to 200,000 cuttings. The house has 50% saran shade on top, a 6 mil. polyethylene on that. One wall is nine feet, the other wall is six feet high. We leave an opening on the highest wall in the summer so the heat can escape. In the winter it is completely covered. The mist is controlled by two 5-minute timers, one for each half of the house. They are connected to a 24 hour

The best times for the propagation of this plant was found to be at two different months in the year - April and September, although cuttings made at these still gave erratic results; some years very good, but in the years only fairly good. When the cuttings were made at other than times mentioned, the results were also erratic, but response was usually poor.

The "hormone" we use is Hormodin No. 1 because the condition of the wood necessitates this concentration. Results have been poor where higher concentrations were used. The cuttings are stuck into a 2 parts Sponge Rok (perlite), 1 part peat moss mix when

Probably the most blame for failure of the grafts can be traced to the condition of scions at grafting time. Scions should be taken only from the season's new growth, and must be made of firm, semi-mature wood.

The side graft method should be used when grafting pines at the ground level in nursery rows this time of year. Since the scion must always be placed on the north side of understock, the rows of understock should be planted in north to

Perennials that are to be propagated by root cuttings, are no different from woody plants in that their roots must be capable of producing shoots. Such shoots are developed from latent (dormant) buds laid down in the initial period of growth, or from adventitious buds formed after the root cutting has been made. Such adventitious buds usually occur in the larger portion of the roots, closer to the crown of the plants.

Generally speaking, in our area (Lake County, Ohio) root cuttings are made in late fall or early winter. For this purpose the desired number of plants are dug in late fall and stored in a cold frame or similar place, until the propagator is ready for them.

The one exception is Oriental Poppies (Papaver

Despite the difficulties involved in securing propagating material, root cutting propagation is by far the best method for increasing certain special plants which will not root from stem cuttings. It is also useful for increasing certain clonal varieties of plants which do not come true from seed, do not bear reliable seed, or are staminate clones of dioecious genera. Here are a few examples of plants