Development of New Insecticides and Fungicides Relation of 'Chemical Research Laboratories IM.D.
Farrar
Crop Protection Institute, Durham, N . H .
-4s spray schedules developed, the demand for chemicals became great enough to interest manufacturers in making and selling agricultural chemicals. Industry followed closely the recommendations of the experiment stations and made those chemicals recommended for use in the various demand areas. Less than twenty-five years ago there was little professional relationship between the chemicals industry and agriculture. Experiment stations were reluctant either to test or publish data on any new product made by a single company. Such work was wrongly classified by many professional workers as advertising. As a result, since governmental research centers could or would not test their new chemicals, industry began to hire its own research staffs. It was to meet this need of an organization that would serve as a liaison unit between manufacturing organizations and the experiment stations that the Crop Protection Institute was established in 1921, under the auspices of the National Research Council. The Crop Protection Institute provided an organization whereby industry could investigate both known and unknown chemicals in the field of agriculture. Through research grants to the institute manufacturers were able to establish research fellowships a t thirty-five state experiment stations. Since its establishment the institute has expended over a million dollars on research. Most of its projects have been with either insecticides or fungicides on plants or animals. From this research seventy-six technical bulletins have been published. Aboht the time the Crop Protection Institute was established, industry entered a new era. The field of chemistry expanded rapidly. I n the manufacture of chemicals, by-products appeared for which there were no known uses. Through research it was found that many of these by-products have useful applications in commerce. There were many factors at work to keep the manufacturing chemist looking to agriculture as a market for his products. As the demandcfor agricultural chemicals developed, costs were lowered, and manufacturing in some fields became highly competitive. To meet this competition large companies organized agricultural divisions to sell and service agricultural products. These companies have in recent years hired many men from the experiment stations to adequately staff their agricultural departments. As the situation now stands the professional status of men associated with industrial companies is comparable to that of men associated with colleges and experiment stations. Industry can support its sales divisions with technical services as efficient as those previously offered by the experiment stations and extension services. The technical man now devotes most of his time to acting as a buffer between his company (sales and service) and the farmer. Instead of working with undeveloped chemicals, he is working with finished products that have been scientifically developed in a company laboratory before they appear on the market. Few people, outside of industry, are aware of the cost of developing a new product. Most chemicals do not reach a market in less than three years and many require six to eight years for development. Manufacturers have spent many thousands of dollars on laboratories, field testing, and final manufacturing.
Fundamental research in agricultural chemicals at research institutes, colleges, and in industry has been made possible through grants and fellowships established and supported by industry. From these programs of research have come new organic insecticides and fungicides whose performance has been so outstanding that the field for new and better agricultural chemicals appears almost limitless.
L
ESS than a hundred years ago the study of insects and
plants was limited to a few men as a hobby. With the establishment of American universities and colleges following the Civil War, means were provided for the professional study of biology. The early workers studied and published much of our present knowledge on the classification, distribution, and life history of our more common insects and plants. With the turn oi the century a'rapidly expanding agricultural program demanded information on destructive insects and plant diseases. This demand furnished the basis for support of a program for the stud1 of our economic forms of plant and animal life. Until about the time of the first world war the work of entomologists and plant pathologists was primarily carried out in laboratories supported by state and federal funds; industry had paid comparatively little attention to the field of agricultural chemicals. This point is of interest because, lacking the support of industry, men worked on problems of insect and disease control with methods of their own design. This was a good trend, because without their subsequent knowledge of chemicals, their energies were spent on life history studies and interrelation of hosts and parasites. They prepared control methods that would take every advantage of the weak points in the life history of destructive plants and animals. Out of these researches came our fundamental agricultural programs of soil fertility, crop rotations, and variety studies. Workers attempted to provide means of increased production in their fields with the tools available a t that time. Many will recall statements by fathers that down on the farm beautiful crops were raised without the spraying, dusting, and fertilizing necessary to modern production methods. This was probably true during the early stages of agricultural development when farming was highly diversified and largely self-supporting. With the development of our large areas of major crops, such as cotton, corn, wheat, and livestock, destructive pests were provided with an unlimited food supply. Also, several very destructive pests were introduced from abroad; some of these mere extremely difficult to control under conditions existing in America. As a result, the cotton boll weevil, Hessian fly on wheat, rusts and smuts on small grain, grasshoppers on grain and pastures, and chinch bugs on wheat and corn, along with many lesser plant diseases and pests often caused economic disaster. Throughout this period the professional entomologist or plant pathologist used very few chemicals. When a few basic chemicals became available, such as sulfur, copper sulfate, lead and calcium arsenate, and Paris green, his energies were devoted to applying them in the best method possible.
680
April 1948
681
INDUSTRIAL AND ENGINEERING CHEMISTRY
Even after sizable investments in research, many products fail to reach a retail market. Such development costs seem unjustifiably high and thus appear to be an excessive mark-up on the finished products, which do reach a market. The development of a new agricultural chemical is often a discouraging process. The men in industrial research laboratories are qualified to make all types of chemicals within the facilities of their respective laboratories. These chemicals would be only shelf stock unless they could be used in some manner. A research project usually starts with a selected number of chemicals from laboratory stocks. These chemicals must first be screened for their biological applications, either through facilities owned by the company or through outside research organizations equipped and staffed to run biological tests. Many companies find that screening can be done by an outside organization at less expense than in their own laboratory. The Crop Protection Institute aids manufacturers by furnishing biological data at a reasonable cost. The work of the institute is typical of that carried on in many of the large industrial laboratories and can be used as an example to illustrate screening. For effective *use on plants or animals an agricultural chemical must kill the insect or destroy the fungus without harm to the host. This is a basic requirement for which many screening tests have been developed. The field of agricultural chemistry is still too new for chemists to be able to predict whether this or that chemical will react biologically. The only satisfactory method of determination is to try the chemical through a series of biological screens, which, in one way or another, may indicate if the chemical has any biological value. Laboratories differ in their selection of test animals and plants. In all cases a large stock of testing cultures must be maintained for the tests to run smoothly. For insect testing, houseflies, mosquitocs, bed bugs, roaches, ticks, grain insects, carpet beetles, clothes moths, Mexican bean beetles, Southern armyworms, milkweed bugs, and aphids are in common usage. For Elant testing, beans and tomatoes are in most common use; many other plants are needed ior special tests. A full biological screen will include ten or more different techniques. Most chemicals are rather specific. Thus a chemical that will ki!l houseflies may be of little value against aphids or leaf feeding insects. Another chemical may. be of no value as an insecticide yet be an excellent mildew-proofer, fungicide, or weed killer. A chemical that shows value in screening tests is further eval&ted for range of usefulness, and dosage level, and
is formulated for application, as a gas, aerosol, wet spray, or dust. Testing and retesting is time-consuming and expensive, but if acceptable after screening, the new product must then be put through a long series of laboratory and field teats. Many field tests will be in competition with similar products from other manufacturers. After the development work is done, management must be sold on the advisability of investing in the necessary manufacturing equipment to make the product. This is generally not too difficult because management is fully aware of the value of its research program and ready to make a product which will be of credit to the company. The finished product can now be turned over to the sales organization which in turn must become thoroughly familiar with the product before it can be sold and properly serviced. In the postwar period the public is extremely pest control conscious. Sales of products for pest control boomed during the war and are still a t very high levels. Furthermore, the market for new and better insecticides and fungicides seems unlimited. For as each new agricultural chemical is developed, new uses are found for i t without seriously disturbing the sales of older, competitive materials. The development of D D T has stimulated research with organic chemicals in many agricultural fields. As a result organic chemicals that have many new uses in agriculture are appearing on the market. Selective poisoning is becoming a fine art; chemicals are used in previously unheard of applications-for example, killing soil-infesting insects, sterilizing soil from weed seeds, weeding crops by spray or dusting, destroying unwanted vegetation, protecting forest areas and products, preventing insect breeding, destroying internal parasites in animals, and a host of other new uses. The balance between nature and living plants and animals is extremely narrow. A slight chemical adjustment one way or the other will result in major shifts of this biological balance. Economically the objective is control of the disturbing factor without injury to the major crop, and one of the most promising methods of control is through the field of chemistry and its application to agriculture. Chemicals are coming from the laboratories faster than they can be tested biologically. Screen tests are almost constantly indicating some promising chemical. From this research will come new methods for the future control or eradication of many insects. RECEIVED November 22, 1947.
Fungicides in Food Production
/
James G . Horsfall Connecticut Agricultural Experiment Station, New Haven, Con-.
In general, fungicides differ from insecticides in that they are protective in action rather than direct. Specifications for the ideal fungicide, theories of the mechanism of killing fungi, and the performance of new organic fungicides are discussed. ARMERS for generations have known the need for fungiF c i d e s . The famous epidemic of late blight and rot of tomatoes in 1946 emphasized this need to home gardeners as well. Chemicals for many fungus diseases are reasonably satisfactory, but other diseases run unchecked for lack of suitable materials. The purpose of this paper is t o report on the useful chemicals, both new and old.
Three facts are essential to an understanding of fungicidal action (2): (1) The use of fungicides is generally preventive. In very few cases can fungicides be used to eliminate infections already begun. I n food production, fungicides are used to protect foliage, fruit, seeds, and roots against damage, during both productionand marketing. (2) Fungus diseases run rampant chiefly during wet weather. (3) As far as is known, a chemical must be in solution before it will kill a fungus. These three circumstances establish a pattern for fungicides, irrespective of their composition, that is an optimum compromise between the factors concerned. RESISTANCE TO WEATHER.Because practical difficulties prevent the application of chemicals during the infective rains, it is
