212 FLORIDA STATE HORTICULTURAL SOCIETY, 1947

in early February, was ideal for large Repercussions from this past season's bad populations. The secondary spread of the lot of bulbs will materialize before another disease was impossible to control. crop is marketed. One example is cited. Easter Lilies and One can" be sure that binder payments cucumbers were planted in adjacent fields cf $500 to $1000 per acre are things of the separated by a roadway. The commercial past. Likewise there will be a big price bulbs of the previous season showed 1/2 distinction between clean and infected -bulbs. of one percent infection after forcing so The present status ofthe Florida'Easter the planting stock was fairly clean. The fall Lily bulb industry will not improve until crop of cucumbers matured about the time the growers realize they must produce a the lilies were nicely above ground. Good good quality bulb. Bulb buyers are largely roguing failed to keep pace with new infec responsible for the present condition of the tions. Cold injury to the foliage masked industry. If purchases, in the past, had the fleck-symptoms so completely that ro been limited to clean fields the individual guing was impossible until new growth made grower would have had an incentive to con its appearance. To complete the picture tinue careful roguing. was the spring crop of cucumbers. At There area few isolated plantings of digging time the visual infection was 80- clean bulbs in the State although many 85 percent. plantings, which appeared to be isolated, It is difficult to convince all growers of were "flecked" out this past season. This the importance of necrotic fleck because illustrates the difficulty of growing clean the disease does not materially affect bulb or bulbs regardless of the distance to the production in the field. Also, there nearest infected field. has been little or no price distinction be The possible solution is for the growers tween clean and infected bulbs. to organize and request legislation prohib Necrotic fleck seriously impairs the forc iting the movement of diseased bulbs. ing performance of bulbs under greenhouse conditions. The foliage is unsightly, the HORTICULTURAL TRADING CO., are often spotted and many plants come blind. Sebring, Fla.

NEW DEVELOPMENTS IN AND APPLICATION EQUIPMENT

John T. Creighton use of this compound has broadened greatly, Head Department of Entontology and the possible uses of this chemical, as University of Florida an , have been extended. In 1947 we find a general tendency toward Gainesville widespread recommendations for the use of In 194'5 the author presented beforethe various formulations of DDT in the control members of The Florida Horticultural So of pests of garden and truck crops, decidu ciety a paper entitled, ''Present Status of ous fruits, citrus, cereal and forage crops, DDT As An Insecticide." In this paper cotton, forest and shade trees, stored seed, an effort was made to present the most grain, and pests affecting the health and pertinent facts pertaining to this compound. comfort of man and domestic animals. Since 1945 research work relative to the The advent of DDT upon the world ento- CREIGHTON: INSECTICIDES AND APPLICATION EQUIPMENT 213

mological scene stimulated terrific scientific ous tests on the phytocidal action of this interest in the development of new chemi chemical. These have included vegetable cals; and the uncontested right of this and field crops, citrus, and ornamentals. compound for the spotlight in world pub Burn records on the plants tested were licity was soon challenged by other notable insignificant. It may be said that plant chemicals, which have proven to be equally tolerance for this chemical is exceptionally valuable as DDT in some respects and su good. perior in others. This treatise deals with Velsicol 1068 () is demonstrat the most promising of these compounds. ing a wide range of insect control qualities Velsicol 1068 (Clordane).—Vesicol 106b that is quite comparable to DDT. Thus, has many characteristics that will encour this is another chlorinated hydrocarbon age its general use in the control of pests. which bids well to have a strong impact It is a chlorinated hydrocarbon, which has upon all types of control. It has proven lesidual action which is not as extended to be highly efficacious in the control ot as that of DDT. This compound is insoluble disease vectoring and pest mosquitoes, in water, but is readily soluble in the usuai houseflies, fleas, , lice, roaches, bed organic solvents such as aliphatic, aromatic bugs, and spiders. Sprays containing this and chlorinated hydro-carbons; also in chemical may be used as space sprays or ketones, ethers, and esters. The proper residuals. Formulations of Chlordane have formulation of Chlordane will enhance its been successfully used in the control of insecticidal value. Compositions may con grain beetles and moths, carpet beetles, ants, sist of solutions emulsions, wettable pow silverfish, fruit flies, and book lice. Wet- ders, dusts, and aerosols. table powders and emulsions containing The determination of the degree of com Velsicol 1068 may be used in protecting do patibility between Velsicol 1068 and other mestic animals from such pests as sucking spray materials is still elementary and in a lice, houseflies, hornflies, mosquitoes, and state of flux. It is quite evident that it ticks. Many of the most prominent of the should not be combined with hydrated lime agricultural pests have also submitted to or other alkaline materials in dust or spray the insect toxic effects of this chlorinated formulations as alkaline diluents reduce the hydrocarbon. Results of an extensive char toxic affects of this compound. acter have not been reported on ornamental Velsicol 1068 may be used sucessfully shrubs and shade trees. Indications are that successful control of , white- with DDT, pyrethrum, thanite, and le- flies, armored scales, mealybugs, leaf feed thanes. Compatibility range of this chem ical will be broadened as studies continue. ers, and others will be possible. Velsicol 1068 in sufficient quantities is Dichloro-Diphenyl-Dichloroethane.— One poisonous to vertebrate animals, including of the most promising closely related com man. The effects of 1068 upon warm pounds to DDT is dichloro-diphenyl-dichlo- blooded animals is comparable to DDT if roethane, which is commonly called DDD, the comparison is made strictly on a weight and is sold under the trade name Rhothane basis. Data thus far indicates that Velsicol D3. This chemical reveals sufficient sta 1068 may be successfully employed at bility to permit storage under varied condi weaker strength, thereby increasing the tions but should not be stored in alkaline safety factor. mixtures. Numerous tests relative to the physiolog Toxicological data assimilated thus far ical effects of Velsicol 1068 upon plants are indicates that DDD is somewhat less toxic being made. Research workers under the than DDT from an acute and chronic poi author's supervision have conducted numer soning standpoint. The insecticidal activity 214 FLORIDA STATE HORTICULTURAL SOCIETY, 1947 of this compound is superior to DDT in may be formulated into oil some instances while in others it is re soluble concentrates, water miscible concen ported as inferior. trates, wettable powders, and dusts. Formu It has proven to be a rather effective lation ingredients should not be alkaline in ingredient in cattle sprays. Its reduced character as this reduces the toxicity of toxicological effect might constitute an en the chemical. It is compatible in chemical couraging factor. It may also be used in formulations containing thanite, pyrethrum, powders for application to animals for the rotenone, DDT, lead arsenate, calcium ar- control of lice, fleas, and other ecto para senate, nicotine sulfate, fixed copper fun sites. It is also proving to be of value in gicides, , and neutral emulsifying and agricultural sprays. wetting agents. Hexachlorocyclohexane.—The chlorinated Laboratory and field experimentation hydro carbon 1, 2, 3, 4, 5, 6, hexachlorocy- have revealed its effectiveness in the con clohexane is commonly known as benzene trol of household and storage insects, pests hexachloride or 666. The crude material of livestock, pests affecting the health and contains the Alpha, Beta, Gamma and Delta comfort of man, pests of field crops such isomers. The Gamma is the most important as cotton, and pests of ornamental shrubs from an insect toxicity angle and com Ortho Ortho-Diethyl Ortho-Para-Nitro- prises 10-12 per cent of the crude. This phenyl Thiophosphate.—This insecticide is isomer was termed Gammexane by one of very slightly soluble in water. However, the early workers. The pure Gamma isomer it is completely miscible in the majority of is a' colorless crystal, practically insoluble organic solvents. It is only slightly soluble in water but soluble in organic solvents. to insoluble in petroleum ether, kerosene, Some of the solvents which may be used and refined spray oils. It is commonly in the formulation of benzene hexachloride known as or 3422. sprays are as follows: acetone, benzene, Parathion may be formulated into emul carbon techrachloride, cyclohexanone, diesel sions, dusts, wettable powders, and aerosols. oil, ether, ethyl alcohol, xylene. Insecticidal It demonstrated good insect toxic qualities preparations of this material may be as in laboratory tests. Field tests are now being dusts, solutions, emulsions, wettable pow conducted in all regions. In Florida the ders, smokes, or aerosols. first field test with this compound was made This chemical has revealed a wide range under the author's supervision in the shade of toxicity to insects. Phytocidal action is grown tobacco belt. 3422 revealed the high rare, and toxicological studies have revealed est toxic efficiency of all insecticides tested that it is a safe insecticide for use in the for the control of the green peach aphid. control of insect pests when used with This chemical has approximately the normal safeguards. Research investiga same toxic range to warmblooded animals tions under the author's supervision have as nicotine sulfate. Phytocidally it seems revealed that it will effectively control many to have a safe range on a number of plants; of the pests of vegetable crops. but may cause injury to some when im Tcxaphene. — Toxaphene is described properly used. chemically as a chlorinated camphene. It . — Hexaethyl is prepared in technical grade and purified terraphosphate has revealed rather excellent forms. This newly developed compound toxic qualities upon aphids and some other is readily soluble in organic solvents, there species of insects. It seems to have ex by making the formulation of liquid insec ceptional initial toxicity to aphid species. ticides and insecticide concentrates easy. It This compound is very dangerous to warm is soluble in water. blooded animals and therefore necessitates CREIGHTON: INSECTICIDES AND APPLICATION EQUIPMENT 215

the use of extreme care in manufacture, the control of soil infesting pests are eth- formulation, and field use. ylen dibromide, and 1-2 dichloropropane and 1-3 dichloropropylene mixture. DD is the Synergism abbreviated name used in referring to a Synergistic action of materials added to dark liquid soil fumigant consisting of a insecticidal chemicals is a field that in mixture of 1-2 dichloropropane and 1-3 terested workers during the war and has dichloropylene. This mixture eflectively been carried over into the post war period. controls wireworms and nematodes. There The initial compound produced commercial is some evidence of carry-over for two ly for this purpose was isobutylundecy- years. It may be retained in soil for ex leneamide. Subsequently there was re tended periods, and thereby injure or kill ported piperine compounds, sesame oil, certain seeds and young plants. Some root piperonyl cyclophexenone, and piperonyl crops may take up "DD1' odor if planted butoxide. soon after treatment. There is some evi Sesame oil, which contains sesamin, was dence of accrued value when DD is com extensively used during the war period as bined with ethylene dibromide. Dosages an ingredient in aerosol bombs for the acti range from 200-700 pounds (20-40 gallons) vation of the . per acre. Spacing should be 16 inches, and a seal is not required. D and O 312, which is piperonyl cyclo- hexenone has some insecticidal value and Etheylene dibromide is another effective also serves as an activator for pyrethrins. fumigant for the control of nematodes and It is commonly called PCH by the trade, wireworms. This fumigant is less phyto- or Pyrenone. Its snyergistic behavior is cidal than "DD," and may at times be ap marked, affecting degree and speed of tox- plied to living plants. A dosage of 2 gallons icity of the pyrethrins. Cyclohexenone of EDB per acre used in a naptha base is seems to be activated also by effective. A range of 1-4 gallons may be thereby increasing its basic insect toxic employed. Spacing should be 12 inches as quality. diffusion range is narrower. Water seal is not required, and soil should not be too Piperonyl butoxide is another synergist dry or too wet. Dowfume W10 contains for pyrethrins that has demonstrated basic 10 per cent ethylene dibromide, while Dow insect toxic qualities. It is readily soluble fume W 40 contains 40 per cent. in mineral oils used as solvents, and in propellents used in aerosol preparation. It DD and Dowfume W-10 are most effec may be used in preparing dusts, wettable tive when a special applicator is used in powders, or emulsions. making soil treatments. Dowfume W-10 is for small garden plots and does not re Piperonyl butoxide has a basic insecticidal quire a special applicator. value and activates and is activated by pyrethrins. Its presence with the pyrethrins Development and Improvement of seems to result in an extended residual Application Equipment effect. The safety of such combinations in The. chemicals discussed have only been crease the usage in domestic areas, and on a few of the many thousands of organic consumable products. and inorganic insecticides that have been tested in the field and laboratory during the Soil Fumigants last eight to ten years. Thus it is revealed Advancements have been made in the that only a comparatively few have proven soil fumigant field that are exceedingly feasible in the control of our pests. Un promising. Two of the chemicals that questionably many additional chemicals will seem destined to play an important part in be added in future years. Problems per- 216 FLORIDA STATE HORTICULTURAL SOCIETY, 1947 taining to the most effective use of these heavy mist which is driven through the insecticides will arise and require patient foliage. investigations by many scientists. Aerosols.—The use of Aerosols were pop If a full realization of the effectiveness ularized during the war period. This type of newly developed chemicals is to be at of aerosol utilizes such chemicals as dichlo- tained it is essential that application equip ro-difluro-methane (Freon 12) as a pro ment keep pace in this period of progress. pellent, and pyrethrins and other materials This is true in order that applications may as toxicants. Their usage is well estab be made with the least labor and costs. Three lished. The use of this application method important factors involved in the application is being extended into the greenhouse and of insecticides are dosage control, uniform on field grown plants. The utilization of ity of application, and proper placement or methyl chloride as a propellent has facili coverage. These are functional require tated the broadened use of this method as ments of equipment. larger particle size is required. Improvements in existing equipment in Fog Generators.—Following the develop clude hydraulic lifts for tower units which ment of the aerosol method came the steam permit them to be pivoted and laid down to aerosol or fog applicators. These use con facilitate travel along roads. The develop centrated sprays which are atomized into ment of the vertical multiple-nozzle boom steam or hot air which create a vapor. This increases the speed and effectiveness of vapor condenses under atmospheric condi spray applications by facilitating the cover tions and is aided in its movement as a fog age of the sides and crowns of trees. by air currents. These machines have at In the field of newly developed application tracted widespread attention but remain equipment there are many interesting somewhat in an early experimental stage. trends. Some of the most important fol Mist Blowers.—Another piece of insecti low: cide application equipment which was ad Sprayer-Duster. — The sprayer - duster vanced during the war period is the Misi combination permits the application of dust Blower. The mist blower utilizes an en or liquid spray alone or in combination. gine-driven turbine (blower) which de When the two are applied simultaneously velops air currents of high velocity. The the liquid acts as a sticker for the dust. current of air is "straightened" and chan These are one man machines which permit neled through a series of baffle-plates into the coverage of 4-15 acres per day. These the barrel or dispersal gun. Concentrated outfits utilize a high air velocity resulting sprays are used and these are finely atom from a 12-inch fan operating at 4000 rpm, ized by the air currents, and propelled con driven by a 4-6 horsepower air cooled en siderable distances. Coverage is excellent. gine. This insures an equalization of air currents. The dust is usually directed into 1 Aircraft.—The dispersal of insecticides the blower or fan of the machine, while by airplane, autogiros, and other machines the liquid is applied in small quantities at is progressing along stable lines. This outlets of air stream. method will receive greater play in the fu Speed Sprayer.—The speed sprayer is ture as methods and materials are perfected. another addition to modern application This is true especially in large areas devoted equipment which utilizes an airplane-pro to specialized crop production and inacces peller blast which moves large volumes of sible areas which prohibit the use of ground air at low velocities. The usual dilute spray equipment. Aircraft applications remain material is used and the air blast creates a in an experimental stage. CREIGHTON: INSECTICIDES AND APPLICATION EQUIPMENT 217

Looking Forward or the amount of organic material or col In reviewing the literature it is emphati loidal clay that is present. cally revealed that newly developed chemi Data is rapidly being recorded that indi cals possess a wide range of toxicity and ef cates the tremendous toxic effect that newly fectiveness. This fact justifies in part the developed chemicals have upon the parasitic enthusiasm with which some scientific and predaceous enemies of economic insect people have endorsed and recommended gen species. Thus has been demonstrated the eral usage. However, complexities resulting abnormal increase of scale insects on citrus, from general usage are beginning to appear aphids on deciduous fruits, and pests of and may in time reflect badly upon those vegetables due to the heavy destruction of who have been too hasty in their appraisals. beneficial species. This upsets the biotic Requirements for the wide-spread use of complex to such a point as to endanger newly developed chemicals are: safety to crop production. Time must be taken in soils; safety to public health; safety to the detailed investigation of all problems plants; safety to farm animals; safety to involved in the use of such chemicals. beneficial insects; and safety to wildlife. It is quite evident that we are well ad Such complete information has not been vanced into a new insect control era. We obtained thus far for the newly developed are well equipped, for this period in human insecticides. affairs, with great Industrial Agencies Indications of troubles arising from ill staffed and equipped for the synthesis and advised use of chemicals are classically illus manufacture of new chemicals, and with trated by the possible effects upon the thousands of well trained entomologists who soils. DDT may tend to retard plant de ask mainly for the opportunity to serve. If velopment when used at certain rates. The provision is made for the proper appraisal retardation effect may depend upon the of these new developments it will result in degree of acidity or alkalinity of the soil, a worldwide advancement of civilization.

FLOWERING TROPICAL TREES—A PLANTING PROGRAM FOR FLORIDA

By Edwin A. Menninger suited for special purpose planting, particu "The Flowering Tree Man" larly highways, parkways, yards, parks, Stuart cemeteries, community forests, special loca tions on the waterfront which are exposed Florida needs a well-rounded program of to high winds, salt spray, or occasional inun ornamental tree-planting. There are three dation, and lastly, trees which best resist distinct zones in this state: north Florida hurricane winds. with its usually acid soil and temperatures In working out such a schedule, we should as low as 18 degrees; central Florida with consider trees that provide a combination of its neutral, or sometimes acid soil, with shade and flowers, those that are particularly temperatures as low as 25 degrees; and useful in providing shade, those that are south Florida, with its predominantly lime distinguished mostly for their showy flow stone soil and a minimum temperature of ers, and. those which, like mahogany, the 32 degrees. tung oil, and many similar trees, can be For each of these areas it is necessary planted with the thought of timber or nur to work out a schedule of the trees best crops.