Proceedings Library

We grow avocado seed in clean soil, in pots on benches. By doing this we avoid most of the fungi problems and have a minimum of trouble. Cleanliness is very important as the seed are forced under high heat and humidity. We prefer to harvest the fruit before it drops so the seed does not become contaminated on the ground. Tip-grafting of avocados was first done commercially by Walter Beck of Fallbrook, Calif. around 1946–48. Shortly thereafter, many growers and nurserymen, including myself, adopted the method. It is a guess that 75% or more of all commercial avocado trees grown today are tip-grafted by the method I will describe.

In our own nursery in Corona, Calif. we generally use the same

While it is true in days past that heat was the primary element added to protect and cultivate tender plants in green-houses, very little was done toward cooling. The only control for high temperature was accomplished by ridge and side ventilators.

With the advent of "pad and fan" cooling the entire concept of greenhouses was altered. Continuous ridge and furrow type houses became a standard. With temperature and humidity control, crops could now be cycled with pinpoint accuracy with maturity dates as prime objectives.

In the past several years, cycled lighting and black cloth have made many technological advancements for the horticultural industry especially in blooming crops. Controlled photoperiods have sophisticated many crops and is

Perry's Plants has benefited greatly by the use of plastics in our growing procedures. We are currently using polyethylene sheeting, 4 mil, for winter covers and protection, as well as the corrugated PVC (polyvinylchloride) for a permanent structure.

The polyethylene sheeting is used for covering, during the winter, our temporary structures, which are made of bent &frac;12" pipe, giving the shape of the quonset hut, with a curved dome top. We have taken a standard 21-foot length of galvanized pipe and with the use of a homemade jig, bent the pipe to conform to the shape that we desire. There is a three-foot straight leg on each end and the rest of the pipe between these three-foot legs is curved into a half-circle. The reason for the straight

At the present time we are propagating in open benches but with air-conditioning fans (on thermostatic control) moving the air directly over the cuttings. We are having a greater percentage of rooting now than ever before.

At earlier dates, we were cautious as to the type of mist nozzle used so as not to get too much water on the cuttings. Now we are using Foggit nozzles; their output is three-gallons per hour. Formerly we used

Two houses were in use from September, 1965, through March, 1966. The dimensions of each were as follows: 30' × 50' &times 15' in height at the highest point. The height is always one-half the width with this type house since it built in a half-circle. Each Airhouse was equipped with a dessert cooler on the south end-wall; a 100,000 BTU heater, thermostatically-controlled, was integrated with a squirrel-cage blower on the north end-wall. One or both of the blowers was in constant operation at all times to keep the houses up. During the heat of the day both blowers were in operation in order to move as much air as possible to keep the houses cool. With approximately 17,000 cubic feet of air in the house, the estimated

From my experience I expect to see air-supported plastic greenhouses become quite common. There will be a diversity of designs for diverse uses. Some will be for long life and great durability against heat, cold and winds. Others will be used with a minimum of cost but with greater risk of destruction.

A few suggestions I might take are the following:

1. A water anchor may have considerable value for certain conditions. I believe it can be most effective as a separate, one-foot diameter (more or less) tube and inserted in a larger fold-back tube made from the main greenhouse sheeting and running

The initial houses were 30 feet wide without posts or trusses. Later models are 40 feet wide. The steel arches are made from 1¼ inch steel tubing. For the 30-foot house, 21-foot lengths of pipe were used while 26-foot pipe was used for the 40-foot model. The pipes are joined at the top of the arch.

The ends of each arch are inserted into a length of 2-inch pipe, 2 feet of which is below ground and 1 foot above. The rows of anchor pipes are 4½ feet apart and adjacent houses overlay by this distance. Thus, the arches from adjoining houses intersect approximately 6½ feet above the ground. Channel iron, or "V" shaped wooden gutters are placed in this junction.

Along the length of the house the

In my lifetime practical propagation has advanced from a largely methodical and empirical concept to one of a more techno-scientific nature. Our nursery has always specialized in commercial propagation and the sale of liners and so we have tried to keep abreast of new methods and techniques and even to look into the future through research, our own and that of others. It seems to me that change in propagation has been brought about by

Discount houses and mass outlet retail centers have mushroomed around suburban living. To become more merchandising-oriented so that we may better serve our sales outlets.

Timing, distribution and packaging are some of the factors involved in marketing.

If you read your newspaper ads you will no doubt become aware that all retail outlets have anniversary sales, 1c sales, birthday sales and what have you, besides their regular holiday specials. To feature a certain plant for their ads, the grower must be informed well in advance since most stores place their copies ahead. We use our IBM system for computing and planning by categorizing our sales. No matter how much planning is involved, timing on certain crops is critical, especially when color is needed for appeal factor

In our own business we have a lot of "chiefs" —so, at the managerial level, we shouldn't be running short for awhile. In fact, I have a younger brother

It is difficult in a classroom or college situation to bring all of the factors of a commercial concern into bearing, for the time we have the students is only a part of their total commitment and they cannot live their entire time in the stress and strain of an economic situation.

We have found several different ways by which we can the student's scientific training, and we feel we have succeeded to a large degree.

First and most important is that the material we present in the courses is of a practical and applied nature, presented by instructors who have had wide and successful experience in the field.

Second, and perhaps equally important, is that field trips are arranged to places of business which are engaged in the type of work we are studying. In this manner we can show the student the extent of the enterprise. It is also an

This somewhat exaggerates a very real problem that we have when training personnel for our nursery operation. Few nursery operations are organized and fully staffed in all departments so that a new employee merely has to imitate the man who is directly in charge of him. If your situation is typical of our operation you may find yourself with a new employee and a new problem. How do I get this man so that he can be left on his own and still give me a feeling of confidence — that of knowing the job is in good hands.

The diversified nursery that we have consists of field and container grown ornamentals, deciduous tree and vine growing, farming of cotton and beets, a complete

First, we shall compare the aspects of the environment—atmospheric and soil—considered of importance sixty years ago and today. Second, we shall take a brief look at some of the structures used to regulate these environmental factors, then and now. Finally, we shall examine

Webster says, "A machine is any contrivance to increase and regulate motive power, an engine, a light carriage, or vehicle." Some of the methods we, at the Bailey Nurseries, are now using do not truly involve machines, but they do involve implements which greatly improve the results and lower the labor costs. We are all interested in improving the quality of our liners, and this it as it should be. Most producers are finding that the buying public is very much interested in high quality and, what is more important, they are willing and

Designing a machine to do certain tasks in a nursery presents many problems normally not encountered in manufacturing. For example,

1. We are dealing with disuniformity. Every plant is — different and, it is dynamic — always changing. At Monrovia we have over 1000 varieties of plants and each variety has its peculiarities. In contrast, in the manufacturing industry the basis of automation is

In the past it has always been not only more economical, but safer, to handle the transplanting of these small plants by hand. As has been pointed out, rising costs of labor, and a disappearing labor pool increasingly lead us to mechanize wherever possible. There have appeared numerous potting machines for transplanting larger plants into sizeable containers, and several semi-automatic machines to aid in transplanting small cuttings and seedlings. What Mr. Hoyles and I hope to accomplish is to develop a machine that will automatically handle and transplant these liners.

To achieve our purpose, the machine must not only be capable of handling and potting these plants, but must do it accurately and

Our senior project is concerned with the aspect of transplanting rooted cuttings and seedlings into plastic pots by machinery. This machine will automatically do all the necessary steps involved in potting. It will handle the plants, the soil and the pots.

An experienced worker can pot approximately 2500 cuttings a day. For any machine to be effective, it must do at least that. Hopefully, this machine will do many times more. In order for such a machine to operate certain theories must be examined and tested. One of these theories would be to eliminate bare-rooting the cuttings by compartmentalizing the flats. Another theory would be to treat the soil

The case was made similar to a grafting case with a 1 × 12 board used on each side. Flats made with wooden sides and 1½ mil polyethylene bottoms were set. on top of this case. The cuttings were inserted through the plastic, leaving the tops above and putting the basal part down into the closed chamber. Black polyethylene was found to induce better rooting than clear poly. A single layer was adequate for summer rooting, but a double layer

Two 18-foot-long greenhouse sections were used, one in each of two separate greenhouses. Each section was isolated by a polyethylene film curtain at each end of the 18-foot length and sheets of polyethylene film were tacked inside the remaining glass area except for the ventilator area. Temperature, light, irrigation and nutritional levels were maintained as nearly alike as possible in both units.

The study was

There is little information to indicate the levels of CO₂ in various types of propagation units. Through the cooperation of Beckman Instruments, Inc. and Select Nurseries, Inc., Brea, California, measurements were made in several types of propagation units of the levels of CO₂, during the light and dark periods. Measurements were made in cold-frame units, mist chambers and in a closed greenhouse maintained with a high humidity, commonly called a fog house. The cold frame units in which cuttings began to root and new leaves initiating showed marked deficiencies of CO₂, during part of the light period. (Table 1) Only slight deficiencies during the light period occurred in the mist chamber and in the fog house. Where the normal level of CO₂, in the atmosphere

For many years, the University of California, Citrus Research Center, has been growing trees in containers for research purposes. Thousands of such trees have been planted in our orchards and have performed as well as field-grown nursery trees. The consequence of our favorable experiences was a decision to discontinue our field nurseries in favor of container growing. Some of

Both systems are used to control the water content of the leaves. The mist system acts by keeping the leaf surface covered with water droplets, or at least covered at close intervals. The fogging machine acts by breaking the water into tiny sized particles which spread out and cover all areas of the cuttings; in effect, it is instant and constant humidity.

In dealing with mist and mist nozzels, the capacity is measured in square feet of surface, in the case of fog machines it is cubic feet of capacity.

Humidifiers, which fog machines actually are, have become fairly common in recent years both in homes and in industries. The measure of capacity of a humidifier must be measured by the amount of water the machine can break up in

By the way bottom heat is

To put this principle to practical use, the graphite-colloidal silica film is made up as a sandwich. The graphite-silica is the meat and the asbestos, two thin layers, is the bread. If the sandwich is to come in contact with moisture it must be made water tight. Laminated plastic films accomplish this. The electric power is introduced into the sheet by the way of two embedded copper electrodes along the edges of the sheet. In September, 1965, the manufacturers' field man contacted us regarding Cellotherm's possible application in hotbed heating. Out of this contact our trials developed with greenhouse propagation.

The tests

Let us briefly review some of the earlier techniques that inspired many of us to change our old ways for new. In 1953 The Phytotektor Method of Rooting Cuttings by Harvey Templeton explained the rooting of cuttings in soil using mist controlled by a humidostat and timer. He related at that time that the technique was an attempted union of the English sunframe and new mist humidification. An idea he obtained from an article lie had read on mist, by James Wells.

A Simple and Inexpensive Time Clock for Regulating Mist in Plant Propagation Procedures by Charles Hess and William Snyder was the title of a paper that aroused a great deal of interest in electrical and mechanical controls in mist propagation.

In contrast, to these techniques, Leslie Hancock

That I, of all people, should get involved in cost accounting is really rather ludicrous because if there is one thing I dislike, it is office work and figures. But, before giving you what I believe to be a very simple but very accurate solution to this whole question, I want to explain how I became involved.

When I first came to America in 1946, to manage the Koster Nursery at Bridgeton, New Jersey, they were growing Rhododendrons entirely by grafting. During that first

In 1957 when Roger Coggeshall was at the Arnold Arboretum, he worked with this clone and by using 2,4,5-TP succeeded in rooting 21 of 35 cuttings. They were made on the 20th of September and potted on the following 12th of February. The slides which follow show cuttings taken from plants of that propagation and they therefore are in a clonal line. Six 3-foot plants were moved into the greenhouse in the summer of 1965 so that soft wood cuttings could be processed as described by Alan D. Cook in Volume 10 of the Plant Propagator.

For some years we had given up the propagation of Rhododendron from cuttings as it interfered with other items to be propagated in October–November. But 4 years ago I was asked to trim some Rhododendron Mrs. C. S. Sargent in early July. There were a number of very nice cuttings on those plants so I could not just throw them away but took them home. It was a very hot day and we had no ice or anything to keep them fresh. We picked out about 100 cuttings, made them and put them in flats under outdoor mist. The result looked very poor after a few weeks so I lost interest in them but when in late October I came to clean out the frame I found about 50% rooted.

This helped me make up my mind to try again the following summer. We again made about 100 cuttings of Mrs. C. S. Sargent which, by the way, is one of the more difficult varieties. We gave it

1. Considerable time and expense are involved and often with only moderate success.
2. Seedling rootstocks have a tap root with a few lateral fibrous roots. This characteristic has been associated with poor survival of transplanted trees.
3. Each seedling rootstock has the potential of being genetically different.

The need for an improved method of propagation of pecan has, therefore, been recognized for some time.

There appears to be only three published reports in American Horticulture literature that deal with the propagation of pecans by cuttings. Stoutemeyer (5) rooted dormant Greenriver pecan cuttings by pre-callusing and treatment with indolebutyric acid (IBA) ; no report was given on whether the rooted cuttings were transplanted. Gossard (1) reported the rooting of pecan

There still are large acreages being treated with these less volatile fumigants. Some of the most common chemicals used are dichloropropane-dichloro-propene (D-D), carbon bisulphide, methyl isothiocyanate, chloropicrin, allyl alcohol, and dibromochloropropane (DBCP).

The individual fumigants have their own application techniques and soil requirements, and it is not possible to list a set of rules applicable to them all. Generally, however, they require the following: soil moisture in excess of 40% field capacity but less than 80%, field capacity. It is best that the soil be moistened and the moisture maintained ten days before application of the fumigant.

ABIES

Abies balsamea presents a problem because our winters are not cold enough and our summers are a little too warm.

Abies concolor is readily available but grows so vigorously that it does not do justice to the dwarf forms. To overcome this problem, we

"On a

Our trials are concerned with the following Juniperus species and/or varieties, and I will briefly describe them

Some weeds carry plant diseases and insect pests while the mere presence of quackgrass in a plant ball is enough to restrict trade by quarantine in some states.

It is now 20 years since the selective action of "Carrot spray" was found to apply to the weeding of evergreen seed beds and that Dinitro killed seedling weed growth promptly on contact but that woody stems were merely defoliated.

Large scale soil fumigation was in use 20 years ago in production of Hawaiian Pineapples and mulch paper was laid by machine. Young cuttings or offsets of pineapples were set through the paper mulch and early growth proceeded with a minimum of interference from weeds. Those weeds that did grow were removed by hand usually by a weed patrol of two workmen much as "spot weeding" is done during the growing season in some nurseries today.

Today soil treatment is a professional job for custom applicators and much in demand in horticulture. Care and calibration of

Despite this great body of experimental work and resulting information, the universal herbicide has yet to be perfected. Furthermore under the multitude of weather combinations of temperature and rainfall, varying amounts of crop injury occur in

This effect is different for different years. I hear the old timers talk about the near famine winter of 1898 and the bad influenza and deep snow of 1917. Many here remember that all Baldwin apple trees froze in New York State in 1935. We are still recovering from the wind and ice of 1963.

The effect is different for different months. Most recent for me was May 6, 1966, when a 24 degree night took all the new growth from boxwood and Taxus. Tulip Tree and White Oak were defoliated in the forest. This damage was associated with the tender stage of growth of the plants. We call this a late spring frost. Then there was the early fall frost of October 7, 1965, with the same dramatic results. In addition, I remember the 60 mile wind and minus ten F. temperature of February 1, 1966.

So

This structure evolved into a quonset house quite accidentally. We had considered, and to some extent, used the type of structures long since made famous by Bill Cunningham. Bill's designs are excellent and their only drawback is cost; about 50 to 60 cents a square foot. This cost can be sizeable when you need houses in multiples of miles. We have four miles of the 14' houses up at present.

Up until three years ago we were using concrete reinforcing wire to support the polyethylene above our cans. It is a material that did do the job after a fashion. It is almost impossible to work around once put in place. Watering is very difficult. Pulling plants is impossible without tunneling in from the ends. Covering is a problem because of the many sharp edges that seem to

We have been using polyethylene almost since the beginning of polyethylene, and many of our methods are a continuing evolution or refinement of what we have done previously. However, the basic principle of polyethylene has not changed. It is a flexible covering that will allow the passing of gases but will not allow the passing of moisture through itself. It took us a number, of years to realize some of the basic advantages of this method. For example, we know that many of the Evergreen Azaleas and Rhododendrons will lose their bloom buds when the, temperature drops to around to 10 below zero; and yet when temperatures dropped to 25 degrees below zero, Azaleas underneath polyethylene protection, did not have their bloom buds damaged in the slightest. We know that there is a

Polyethylene plastic was just coming into the picture around this period so we constructed a small house (12'×96') by bending some old electrical conduit into a half circle and covering with some concrete mesh wire 6"×6", thus making a quonset type of house. We installed a small exhaust fan in one end and several louvers in the opposite end, plus a couple of propane gas heaters used for curing tobacco in the Southland. The idea was to keep the plants just above freezing, with plenty of air to prevent leaf drop. The following spring the results were so gratifying, plus the fact the Azaleas were gone in no time, that we decided to expand this idea.

We constructed 12 gutter-connected houses with a truss type of roof design of ½ pitch for quick snow removal. These houses are each

1. The houses had to be low in cost.
2. They had to be able to hold snow loads of 6"–12".
3. They had to withstand winds in excess of 60 MPH.
4. They had to be easily erected and dismantled as we intended to put up the houses in the fall and take them down in the spring.
5. They had to do an adequate job of protecting the plants.

The structures I am going to describe are now being used for their third

Since the number of potential soil mix preparations is infinite, we should look first at the underlying economic factors which must influence our choice of formulation.

1. Cost of raw materials is an obvious consideration. Why pay $5 for something which can be obtained in equal quality for $2.50? The

First — ROOTED CUTTINGS:

We do not have occasion to store great quantities of rooted cuttings for any period of time, but we do store rooted cuttings of Crimson Pygmy Barberry and several varieties of Taxus. These are stuck as semi-hardwood cuttings in greenhouse propagation benches during September. We carry them in the benches until about the first of February, then dig and wrap 100 per bundle in moist sphagnum moss and two millimeter polyethylene. We tie the wrap with a rubber band. We do not put the polyethylene over the tops. In fact, the tops of the Barberry cuttings are above the polyethylene about one-half inch, and the Taxus cuttings may be from one-half inch to three inches above the poly., depending on the length of the

It is a real pleasure to discuss with you this morning the most fascinating, perplexing, and at times incomprehensible, phase of plant reproduction … seedling propagation. Over the years we have heard excellent papers presented covering many aspects of seedling production, and it is my intent today to discuss a few techniques we use at Plumfield Nurseries in Fremont, Nebraska.

Our seedling operation is divided between seed beds and seed rows, and most of the remarks and slides will concern the former. The field which encompasses our seed beds is very level, and the soil texture is quite sandy. There are approximately thirty acres of seed beds in this field. Perhaps I should pay more attention to the soil pH, and to N., P., K., but I don't — except that based on previous soil tests, we are quite high in both Potash and Potassium. These results are compiled on a response based on field crops. Soil pH is rather

Terminal applications could be advantageous if they improved rooting without injury to the plant, or if they could be applied as a spray to cuttings in the propagation bench. Theoretically, it is feasible to apply auxins to the terminals of cuttings. It has been established by Went and White (5), and more recently by Leopold and Guernsey (2), that when IBA was applied to the distal (terminal) end of a coleus cutting some auxin

Hormones for plant growth are comparatively new. Baileys Nursery Manual, 22nd addition—a wonderful book in many ways published in 1919 says nothing about hormones. Neither does the article signed by B.M. Watson in Baileys Encyclopedia mention Hormones. Laurie and an assistant Professor named Chadwick in Modern Nursery mention Potassium permanganate and Sucrose as rooting aids. Their book was published in 1931. Also slight attention is given to acetic acid, Manganese sulphate and Manganese dioxide.

Hottes in How to Grow Plants (1940) cites the work that Boyce Thompson Institute did in this field since 1924, mentioning Dr. Hitchcock and Zimmerman, who defined a hormone as a substance produced in one part of the body usually ductless glands and is then transferred to another

Gibberellic acid has been tested in various experiments by many researchers with the purpose of determining its usefulness in the field of horticulture. Much has been discovered with respect to the effects on the above-ground parts of plants. Little information was available in 1957 on the direct effect on root promotion as in the case of cuttings or root growth as it is affected by treatments with gibberellic acid. For this reason the following study was carried out. It was conceivable, as in some ways gibberellic acid duplicated the response of plants to treatment with known auxins or plant hormones, that the material might also favorably affect root induction in plant cuttings. The effects of the known auxins were well established, toxicity levels were known, and the inhibiting effect on root growth was known. Little information was available at the time concerning this phase of research using gibberellic acid. From literature available it was evident that

With the discovery, in the mid-1930's, of the stimulating effect of indoleacetic acid and related compounds on rooting, it was hoped that successful rooting of all stem cuttings would be relatively easy. Such a naive idea, however, was soon expelled for, as was soon learned, the cuttings of many plants remained difficult to root even when treated with these chemicals.

There are numerous factors which contribute to a possibility of disease in the propagation bench. The use of soft, succulent plant tissue, the frequent presence of systemic diseases within the stock plant, the everpresent spores of fungi on the plant, in the air and the medium, the use of warm, humid conditions which are equally suitable for growth of

In October 1965 I purchased a newly developed 100 watt Westinghouse Viscount Mercury Vapor Light, no. 890D569G33, for experimental purposes. The Mercury Vapor Light, according to the electromagnetic spectrum consists of 20% ultra violet rays from bactericidal of 2,500 angstrom units through the erythemal and black light to 3,800 angstroms. These rays do not produce energy. The remaining 80% of light which is energized are the visible rays of 3800 to 5,800 angstroms. From this information it can be concluded that the mercury light contains more natural sunlight than any other artificial device. Infrared rays are present in small quantities.

Mercury Vapor Lights of higher intensity are also available, for example, Westinghouse no. 890D569G43 175 watt and no. 890D569G53 250 watt.

The plastic shield which is included with the lamp

For such a program to be of value to the majority of people in the state, it was necessary to test not only at the University of Vermont (in the Lake Champlain Valley) but in other parts of the state as well, since Vermont includes a range of average annual minimum temperatures from -10 to -15° F. in the southeastern corner, to -30 to -35°F. in the northeastern corner.

Fortunately, quite a number of species had been observed previously in Vermont, due to the efforts of local nurserymen and other people willing to experiment with new plants. Additional information

In order to obtain an indication of the strength of the root initiation effect, one gram of TSE was dissolved in 10 ml of methyl alcohol. A serial dilution was prepared by reducing to one-half the amount of TSE for seven dilutions; the last dilution contained 1/128 as much as the first. Twenty lambda of each extract was spotted on filter paper and tested using Hess' mung bean rooting bioassay. In this case 1 on the ordinate represents 0.05 cigarette or 2 mgr. of TSE. Maximum activity of 68 roots per cutting was obtained with 1 mgr of TSE.

When TSE is chromatographed in

PROGRESS. If measured by the number of successful installations now operating at high efficiency, and yielding daily benefits to nurserymen, such progress in my opinion can be summarized as:

We

Cercis "Oklahoma" was discovered in Spring 1964 in the "Arbuckle Mountains" of Oklahoma. The flowers are a rich wine red over the entire bloom. The leaves are almost round, heavy textured with a glossy sheen that appear to be waxed. The leaves are closely spaced creating a neat appearance throughout the growing season. The trees start blooming at one year and bloom heavily at an early age. This tree seems to grow more compact and will probably not grow as large as the Cercis canadensis.

The "Oklahoma" Redbud is thought to be a natural hybrid between Cercis reniformis and Cercis canadensis having some characteristics of each. The best method of propagation is by

DICK VANDERBILT: I think you can get about 10 days of useful heat between 5 and 0° F. This seems to be what it did. You can take the penalty out of the first deep freeze and if you continue to get low temperatures the rest of the winter you are just going to stay cool. But at the five days at near zero temperatures the water in the canal will be just like a frost in October. In the other houses the cans will be frozen up completely.

RALPH SHUGERT: If potted evergreens showing fall discoloration are placed in unheated greenhouses covered with opaque plastic — will the "greening up" process in spring be hastened or retarded compared to clear poly shaded 25% by white latex paint?

KNOX HENRY: Our experience

At the same time, little attention has been focused on factors influencing the stock plant from which the cutting is taken and how temperature, light intensity, nutrition, photo-period, hormones treatment, moisture, and other factors might influence rooting of the subsequent cuttings.

We often think of a cutting as the beginning of a new plant, but it is really the continuation of an existing plant and what the cutting will or will not do is to some degree influenced by the environment conditions under which it developed as the

However, many workers have shown that nutrients applied to woody plants during the spring and summer often produced no additional growth the year they were applied, but rather were absorbed and stored within the plants. The year following the nutrient applications, important growth differences were noted. Thus, the spring growth of woody plants is dependent to a large extent upon nutrient reserves accumulated in the plants prior to the spring flush (4), that is, during the dormant season. Thus, it becomes obvious that nutrients applied during the dormant season might be effective in promoting a greater amount of spring growth. However, the

In recent years there have been rapid gains of knowledge in the fields of growing plants under stress. The coming of age of container growing has caused us to question many of our previous values and to investigate areas and industries that seem quite foreign to us, for the answers. Some of the areas in question we have discussed at this meeting, such as winter protection. Others, such as the medium requirements brought about by the short soil columns in cans, is causing quite a stir in the wood processing industries as they see a large potential market for their wood by-products. In California, redwood sawdust has gone from a material which the mills were glad to see you haul away to a rather high priced item of short supply today because Dr. O. A. Matkin, of Soil and Plant Laboratory, Inc. developed its use as a soil amendment. Another area which is still undergoing a revolution is that of plant nutrition and how to supply it. It has become increasingly obvious that

1. They can be applied at the rate required by the plants without causing excessive loss by leaching.
2. The nature of the release allows for reasonable mistakes and over-application without burning the plants.
3. Frequent application of fertilizers will not be required.

The characteristics of the slow-release and long-lasting fertilizers described in this paper are attributed to the following techniques:

1. Membrane Coating. Fertilizers are coated by membranes of various sources and thickness. When the fertilizers are in contact with moist soils, water enters through the membrane and dissolves some of the fertilizers in the capsule. The dissolved fertilizers diffuse out of the membrane into the surrounding soil. The rate of release is manipulated by the thickness of the membrane. This technique may provide

Increasing use of the in vitro approach in botanical investigations and the expanding store of information prohibit a thorough coverage of the subject. This article is intended to simply acquaint the unfamiliar with some highlights of principles. Citations to original research should be viewed only as examples for illustration. More extensive coverage, including the historical development, can be obtained from several reviews and symposium publications now available (4,5,8,11,13,21,27,28,34,35,39,42,43).

The term "plant tissue culture" has been popularly used indiscriminately to denote cell, tissue and organ culture. It is desirable to distinguish between cell and tissue on one hand and organ on the other, since their behavior and requirements in culture are markedly different. The preferred term which encompasses each of these cultures is "in vitro culture" and it is therefore used in this article.

Fundamentals which apply to any in vitro culture shall be examined

It is interesting to speculate on possible potential uses of such tissue culture techniques in plant propagation. Several possibilities come to mind:

1. The use of tissue culture as a means of rapid propagation of new cultivars, especially hybrids which require a complicated seed production system.