Science and Industry

on the World Today

IN SCIENCE, as elsewhere, news that makes headlines often gives a one-sided picture of events. Electronic brains and awesome atomic forces are only a small part of what interests scientists. The tang of a juicy apple, the fresh sweetness of a pear, the green fountain of an elm flowing high over a village st reel—these too are their professional concern.

It doesn’t take a scientist to know that apples in a city market aren’t what they used to be out on the farm. Struggling with blights and pests that can turn a season’s work into red ink, orchardists have naturally concentrated on disease-resistant varieties, with the result that only a Couple of dozen of the 2000-odd kinds of apple are commercially grown today. Much of the blame can be placed on fireblight, a bacterial infection that attacks. blossoms and young fruit, leaving the trees withered and brow n as if scorched by Manic.

Pears are even more susceptible to fireblight than apples. To avoid the disease, U.S. commercial pear-growing has been limited to a few areas and a relatively few varieties.

Medicine for fruit trees

Today antibioties that have produced miraculous results in medicine are being put to work to help fruit and vegetable growers fight fireblight and other bacterial diseases that have cost them millions of dollars.

So far, streplomycin has proved the most useful antibiotic for the plant pathologist. Used on apple trees at the Ohio Agricultural Experiment Station, a streptomycin spray cut fireblight infection of blossoms to 2 per cent as compared with 83 per cent on unsprayed trees. Tests with a streptomycinTerrumyein compound in Missouri also gave dramatic results.

Antibiotic sprays have been equally effective in protecting pear trees against fireblight. In spray tests in Marysville, California, a streptomveinTerramcyin combination cut the rale from nine areas of infection per tree to one for every six trees. It is hoped that the drugs will make it possible to resume pear-growing in the East, where the more humid climate makes the trees extremely vulnerable to fireblight. In both apples and pears, the antibiotics control the disease at the blossom stage.

Walnut blight has been successfully at tacked, and streptomycin is the first product to combat the halo blight in beans. The tobacco blue mold fungus, bacterial will of chrysanthemums, and bacterial spot in pepper and tomato plants have all yielded to streptomycin either alone or in combination with Terramyein. Encouraged by these results, Charles Pfizer & Company, manufad uring chemists, have put on the market a commercial mixture of streptomycin and Terramyein called Agri-mycin 100.

Cost is likely to be the deciding factor in how widely antibiotics will be used in agriculture. They are more expensive than conventional sprays, but much smaller quantities are needed. The cost of antibiotics lias already dropped sharply in the past few years, and development of a mass agricultural market should reduce them further.

Meanwhile scientists are experimenting with other antibiotics. The potentialities of musann for treatment of the dreaded Panama disease of bananas is under lest. Cyeloheximide, or Acti-dione, is being tried experimentally on such plant diseases as powdery mildew, cherry leaf spot, rust of mint, and turf diseases. Cyeloheximide, a fungicide, is produced by the same soil fungus that elaborates st replomycin.

Spraying has proved to be the most effective application method for antibiotics. Since some antibiotics are produced by soil organisms, however, attempts are also being made to use them on plants by introducing the manufacturing organisms into the ground, in the hope that they will make antibiotics on the spot. So far artificially introduced organisms haven’t produced enough residual antibiotic in the soil to be detected.

Preventing food spoilage

Other experimenters are try ing to learn whether antibiotics can stimulate plant growth. The use of antibiotics in the prevention of food spoilage is also being studied. Some foods, such as meat, are injected with the antibiotic; others are dipped into weak solutions. Antibiotic solutions are even experimentally frozen into the ice in which sea food is preserved.

There is discussion of the possible use of antibiotics as insecticides. Antibiotic insecticides would be useful, since they might simultaneously kill off the pests and help to protect a food from spoilage.

There is a particular appropriateness about the agricultural uses of streptomycin and other antibiotics, for their discovery owes a great deal to the work of agricultural scientists. Dr. Selman A. Waksman, who won the 1952 Nobel Prize as codiscoverer of streptomycin, was trained as a soil microbiologist, and did his work at the College of Agriculture of Rutgers University.

The emphasis on the dramatic results obtained in medicine has delayed the experimental use of the antibiotics elsewhere, as did their high cost and limited availability for some years. When agricultural research did begin, the initial results were unfavorable — partly because of poor formulation for protection of the plant.

Dutch elm disease

In their study of antibiotics, the agricultural scientists have learned that these chemicals are absorbed and transported within the plant. This action of the antibiotics reflects a quiet revolution in treating plant diseases. Until recently, treatment centered on external pests — insects or fungi. Now, however, pathologists are learning how to fight certain internal diseases—those caused by bacteria or viruses — by systemic treatment: giving the plant “medicine” that operates through the plant’s own distributing system.

At the College of Agriculture of the University of Rhode Island, this approach is now7 being used in a vigorous attack on the dreaded Dutch elm disease. To date there have been some notable successes but also some disappointing failures. The research scientists are not yet willing to commit themselves, but the more hopeful among them are of the opinion that they are on the track of a proventive for the disease that threatens to destroy America’s most beautiful shade tree.

Introduced from Europe on the eastern seaboard of the United States in 1930, the Dutch elm disease has now spread well into New England and across the Middle West as far as Missouri.

It is a complicated ailment. Spores of a fungus are carried from tree to tree by a beetle that lays its eggs under the bark. In each victim the fungus starts growing in the watercarrying tissues. The villain, however, is not the fungus itself but a still unidentified toxic substance that the fungus gives off as part of its metabolic operation. One guess is that the “toxin” is some sort of enzyme that breaks off molecular fragments from the cell walls of the surrounding tissue. These fragments form microscopic “log jams” that block the tree’s circulating system.

Rhode Island experiments

Established treatment has involved either the ruthless destruction of diseased trees — which has retarded but not halted the spread —or insecticide sprays to destroy the beetles which carry the disease.

Now the pathologists at the University of Rhode Island are concentrating on the systemic approach, using a drug made by American Cyanamid, called sodium 4,5-dimethyl-2-thiazolymercaptoaectate. Just how it works is still uncertain, but apparently in some way the chemical makes the cells of the tree more resistant to the toxic material produced by the fungus. It can be applied in several ways, but the most effective is injection into a series of holes drilled at an angle so as to reach the sapwood and spiraled so as not to ring the tree.

Sodium 4,5, etc., was first tried in the field on a relatively small number of trees in the summer of 1953. Young elms were treated with the chemical, then inoculated with Dutch elm disease fungus. Severity of the disease was reduced by 90 per cent. On the basis of this outstanding success a patent was obtained. But a larger test in the summer of 1954 was disappointing. Further trials during the past summer indicate that time of application with regard to the growth activity of the elm may determine its effectiveness.

What went wrong with the treatment between 1953 and 1954? There are two theories. Impurities since discovered in a fresh supply of the drug used in 1954, and in part of the 1955 treatments, may have made it ineffective. If so, it is a relatively simple matter to improve the manufacturing process. Some pathologists feel, however, that time of treatment, progress of the disease, and the age and general health of the tree can all affect the outcome. If they are right, a long period of field trials under a wide variety of conditions lies ahead.

The Rhode Island researchers are encouraged that some 150 campus elms treated with the chemical have all remained healthy, although Dutch elm disease now kills 2 per cent of Rhode Island’s elms each year. Dr. Frank L. Howard, in charge of plant pathology at Rhode Island, believes that if the treatment is perfected to the point where it consistently cuts the kill by 80 or 90 per cent, Dutch elm disease will no longer be a major menace. The cost of treatment, based on experience with the University’s trees, would probably run about $5 a tree, mostly for the hole-drilling, plus 82 for an annual booster shot.

Two other tree diseases, oak wilt and maple wilt, are also caused by “toxins” resulting from infection by various internal fungi. If Rhode Island’s Dutch elm research is ultimately successful, it may well point the way to effective treatment for those destructive wills as well.

Picture on tape

Cartoonists, notably conservative in their choice of symbols, still use the old-fashioned tin-man robot as the personification of advanced technology. In this electronic age a more appropriate symbol would be a long piece of plastic tape. Because tape coated with iron oxide can store electronic signals and reproduce them on demand, engineers have given it scores of jobs, from recording concerts to running huge machine tools.

A whole new area of application has opened up with tape that records not only sounds but sights. In television, a visual image is transformed into a series of electronic impulses; now these impulses can be stored indefinitely and turned back to visual form — through a television receiver — as often as desired.

The picture can be recorded in black and white or color, just as in conventional photography. In fact, General Sarnoff, head of the Radio Corporation of America, has aptly named the process “electronic photography.” It is the first real rival to conventional — or chemical — photography since Daguerre.

RCA is one of several companies working on the tape recording of video signals. So far as information has been made public, it is the furthest along. For several months now a portion of every NBC color telecast has been taped on an RCA experimental recorder. On the basis of this practical field test, RCA engineers expect soon to turn to the design of a production model to be sold commercially.

These first models will go to commercial TV studios to record programs —particularly color — for later telecast. This first application of the new process won’t mean much to most TV viewers, since studios can already do essentially the same thing by aiming a movie camera at the screen of a monitor receiver.

To the telecaster, tape offers many advantages. Every time a picture is changed back and forth between an electronic and a chemical image, some of the quality is lost. At the same time, developing and printing photographic film is time-consuming and sometimes hazardous, particularly with color. The tape will eliminate the danger of damage to the recording, and permit it to be used at once. While tape costs initially more than film, it is cheaper for the studio since it can be wiped off and used over and over again.

TV recorders for the home

For the general public, real interest in video recording will come when simplified design and quantity production bring the cost of a tape recorder down to a level where an amateur can afford it. It will then be possible for anyone with a video recorder to make a permanent record of a telecast. Immediate playback without processing will be possible, and the tape can be used many times with little or no Joss of quality, then wiped clean for reuse when the owner finally gets tired of the particular program.

Judging from what has happened with audio tape recordings, collectors will gather it whole library of favorite telecasts and swap or sell each other duplicates.

Conceivably, it may someday be possible to purchase commercially recorded tapes of plays and operas that can be seen on the screen of the home TV set. In this case, however, duplicating tapes in large quantities presents certain manufacturing problems.

One interesting possibility is the development of a complete system for making home movies electronically. There are already lightweight, highly sensitive television cameras on the market nearly as low in bulk and price as the fancier amateur movie cameras. Combining one of these baby TV cameras with a video recorder would make it possible to take motion pictures that need no processing. Any TV receiver would serve as a “projector.”

Right now, these small TV cameras are finding wide use in closed television circuits for schools, business, and industry. Here the tape recorders can be used to keep permanent records of everything on the circuit.

One field to which electronic photography may not apply is commercial movie-making. Hollywood makes movies in the cutting room. It is hard to edit tape-recorded pictures because of the high speed at which the tape moves, although this difficulty is not insoluble. For TV newsreels, the time saved by the elimination of film processing may more than compensate for cutting problems.

Successful recording of a video signal on a half-inch strip of plastic is a noteworthy achievement on the part of RCA’s engineers. An ordinary sound tape holds a single electronic signal with it frequency range up to 20,000 cycles a second. In contrast, a color TV recording tape must hold not one but six sets of signals, and three of these sets must cover a range of frequencies up to 4 million a second—or 200 times as much as the single audio signal on sound tape.

RCA engineers have achieved this miracle of compression in part by an improved recording head, in part by speeding up the tape movement to 200 inches a second. This high speed has required, in turn, new mechanical designs to make the tape wind and unwind at an exact speed, inasmuch as even a minor fluctuation distorts the picture.

“Natural" rubber

Announcement by Goodrich-Gulf research chemists that they have succeeded in synthesizing natural rubber has aroused great interest among their professional colleagues. GoodrichGulf has told little about the process, presumably waiting until it has thoroughly explored the subject in order to secure full patent protection.

The industrial benefits of a synthetic natural rubber appear limited. The synthetic rubberlike substances already in use—the elastomers that the public knows as “synthetic rubber”— together with the relatively low cost of natural rubber, indicate a small peacetime demand for synthetic natural rubber. What interests the chemists, however, is the hint the discovery gives that it may be possible to produce synt hotically some of the other giant molecules, including those involved in the creation of living matter from inert minerals.

True rubber is a natural polymer, one of a group of molecules that includes such vital substances as proteins and starches. While artificial polymers such as Dacron and plastics can be made by man, until now no naturally occurring polymers have been synthesized. Scientists are particularly eager to find ways to synthesize the proteins—especially those proteins that net as catalysts in all biochemical processes: the enzymes, it is the enzymes t hat bring about the processes that make life possible. If chemists are ever able to make an enzyme synthetically, they will then try to synthesize one that will reproduce itself. If that occurs, man will have pried into the original mystery: the creation of living cells out of inanimate molecules.

There are a lot of ifs ahead. But the synthesis of natural rubber changes the whole climate of this research, since it was previously felt that any attempt to synthesize a natural polymer was hopeless.