F1otation Sulfur in Agriculti \ INCENT
QAUCEIELLI
Koppers Research Corporation, Pittsburgh, Pa.
A new type of sulfur is described which is recovered from coke-oven gas by means of liquid purijicalion processes. The physical cliuructerislic which distinguishes this sulfur is uniformly microscopic particle size. The anerage size is about 3 microns. A brief outline is given of the sulfur-recovery liquid purificution process. Recent investigations of competent plaid pathologists ure included which link high toxicity of sulfur fuugicides directly with finenew of particle size. The carious applicutiom of this sulfur in the Jield of agriculture as a fungicide, insecticide, und soil cortditiuner w e described. Typicul resulk are ginen of the control of such fruit diseuses as apple scab (Ventaria inequalis),peach brown rot (Sclerotiniafructicola),wheal rust (Pucciniu), und peach scab (Cladosporium carpophilum). Datu are subniilted which show the eficacy of this sulfur in reducing the alkalinity of soils on the Pacific Coast.
UCCESSPUL fruit growers kimw too well the necessity of adequate protection against diseases and pests if profits are to be made from the orchard. Quality fruit, the kind which minmands a premium in the market, is fruit that has heen properly sprayed with the right kind of spray material. I n this lies the problem, for how is the grmver to know which is the right material? Most of the spray materials he has had to use in the past cause more or less injury to his fruit nod trees. He has been hoping against hope for an improved product which could be relied upon to give good commercial control without injury. This article describes a new spray material which has been developed as a result of extensive and careful research over a period of nrore than five years, iiivolving the labor of a large number of phytopathologists and prominent fruit growers. ;5o claim is made thnt this pmdimt is a cure-all or the answer to the fruit-grower's prayer, althnugh tliousands of leading growers in all ecctions ur the country seem to find it satisfactory. The new material is a type of natriral sulfur which is derived from bituminous c:oal. Millions of years ago it was a part. of the weird iplant life which covered the areas now constituting the coal fields of our country. After all this time it is now made to serve agricultiire. When coal is carbonized to produce coke and gas, the sulfur is driven off as a
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gnaeous compound kmnvrr eherrrically as hydrogen sulfide. This compound is an impurity in fuel gas. The gas industry has given careful study to the problem of its removal. Many different methods have been proposed and are in actual use. One of the most. modem, efficient, and economical methods was introduced to the industry by The Koppers Company and is known as the liquid purification process. This is essentially a method of absorbing the hydrogen sulfide in an alkaline solution. I n the prescncc of a suitable catalyst, the hydrogen sulfide is broken down to yield elemental sulfur. The sulfur is recovered by a flotat.ion process in the form of extremely fine particles which approach colloidal dimensions. It is called "flotation" sulfur because of the method used in its recovery. I t is prepared for the market in three forms: a wet past?, N dry wettablo dost. and a dry dust. IS l?LoThTlUs SULFUR I)IX.FEREXT?
13efore presenting the data on field tests and expcriences in disease control, it may be pertinent to give a t this point information about flotation sulfur which will explain why it has proved so successful. Figure 1 reveals how uniformly fine are all the particles. The three sulfurs illustrated were enlarged to the same diameter. This property of uniformly microscopic size is one of the chief advantages wlrich flotation sulfur has, and places it in a class of it.s own arnoiig similar competitive productse Ttihle I emphasiaes the comparative differences anionp t h various sulfur?.
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SLIildbk Sur coinbiiiation with it fungicide for flirr piirpuse of controlliiig both fiingoiis diseases and insects in single dormant spray application. Either tiicy ~ ( ~ u lnot d mix satisfactorily with Ihrdeaux, lime-sulfur, or other sulfur materials, or tire coirrbinatim proved injurious, or the oil lost effectiveness. This newly developed oil-flotation sulfur rrrixture Itas owreime sll t1it:se ohjeet,ions, and extensive fieldtests iecial merits to sprw tire fruit prowcr.
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E. A . Mdiregor of the United States 1)epartiiieiit of Agriculture lias demonstrated t,lre value of flotation sulfirr dust of the type known in (:alifornia as gra.y, or black gns-lrousc sulfur in tire control of citrus thrips. His results apply particularly tu conditions in Tillare ninty, (lalif. IvkGregor refers specificdlly (9) to tlie cmr +.ently superior sirowing of this sulfur against nll competitive sulfurs. This satlie investigator reports (10) satisfactory control of the gray citrus scalc, Citn>oki, by inearis of tire same flotation sulfur wliieh controis thrips. Ile Oiig reported in 1925 ( I f ) that gas-housc sillfur gave very good control of red spider or1 prunes, almoi1ds, Ream, and ornamentals. Oood results were 111)tainted in limited expcrirnemts on grape mildew and on clover and cantabiipe mildew in Oregon and Idaho. Inng-time experiments in several states show that flotation d f u r en11 be used with satisfactory results for the control of cherry leaf spot, gooseberry leaf spot (21, black spot of the rose, brown canker of the rose ( f 5 ) ,rose mildew, and the In-incipal rusts of ornanrentals.
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