'7.7-" Property of the United Si Second edil ion U.S. DEPARTMENT OF AGRICULTURE, Bl l:i A.1 OF PLANT INDUSTRY I ircular No. 1. B. I GA] l ■ >fl AY. Chief of Bureau. SELF-BOILED LIME-SULPHUR MIXfURE AS A PROMISING F UNGICIDE. - I L \V. M. M'OTl. ' <-* *■• **^ S. DEPOSITORY 1'aiiioi ( 1018T en Charge of < >rch ird Spraying Dem< instb ^tions 1 N \ I STIGATION'S OF I >I8E ISES OF l'lM I 1 9. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1903 BUREAU OF PLANT INDUSTRY. Pathologist and Physiologist, and Chief of Bureau, Beverly T. Galloway. Pathologist and Physiologist, and Assistant chief of Bureau, Albert 1". Woods. Laboratory of Plant Pathology, Erwln 1". Smith, Pathologist in Charge. Investigations of Diseases of Fruits, Merton B. Waite, Pathologist in Charge. Laboratory of Forest Pathology, Haven Metcalf, Pathologist in Charge. 'I i in I, Crop Diseases and Plant Disease Survey, William A. Orton, Pathologist in charge. Plant Life History Investigations, Walter T. Swingle, Physiologist in Charge. Cotton Breeding Investigations, Archibald D. Shamel and Daniel N. Shoemaker. Physiolo- gists in Charge. Tobacco Investigations, Archibald I>. Shamel, Wightman W. Garner, and Ernest II. Mathewson. in Charge. Corn Investigations, Charles P. Hartley, Physiologist in Charge. Alkali and Drought Resistant Plant Breeding Investigations, Thomas II. Kearney, Physi- ologist in Charge. Hoil Bacteriology and Water Purification Investigations, Karl P. Kellerman, Physiologist in Charge. Bionomic Investigations of Tropical and Subtropical Plants, Orator I'. Cook, Bionomist in Charge. Drug and Poisonous Plant Investigations and Tea culture Investigations, Rodney n. True, Physiologist in charge. Physical Laboratory, Lyman J. Briggs, Physicist in Charge. Crop Technology and Fiber Plant Investigations, Nathan A. Cobb, Crop Technologist in Charge. Taxonomic and Range Investigations, Frederick V. Coville, Botanist in Charge. Farm Management Investigations, William J. Spillman, Agriculturist in Charge. Cram Investigations, Mark Alfred Carleton, Cerealist in Charge. Arlington Experimental Farm, Lee C. Corbett, Horticulturist in Charge. Vegetable Testing Gardens, William W. Tracy, sr., Superintendent. Sugar-Beet Investigations, Charles O. Townsend, Pathologist in Charge. Western Agricultural Extension Investigations, Carl S. Scofield, Agriculturist in charge. ltru Land Agricultural Investigations, V.. Channing Chilcott, Agriculturist in charge. Pomological Collections, Gustavus B. Brackett, Pomologist in Charge. Field Investigations in Pomology, William A. Taylor and G. Harold Powell, 1'omologists in Charge. Experimental Gardens and Grounds, Edward M. Byrnes, Superintendent. Foreign Seed and Plant Introduction, David Fairchild, Agricultural Explorer in ('barge. Forage Crop Investigations, Charles V. Piper, Agrostologist in Charge. Seed Laboratory, Edgar Brown, Botanist in Charge. Grain Standardization, John I >. Shanahan, Expert in Charge. Subtropical Laboratory and Garden, Miami. Fin., Ernst A. Bessey, Pathologist in Charge. rinni Introduction Garden, Chico, Col., August Mayer, Expert in Charge. South Texas Garden, Brownsville, Tex., Edward C. Green, Pomologist in Charge. Cotton Cull me farms and Canines' Cooperative Demonstration Work, Seaman A. Knapp, Special Agent in Charge. Seed Distribution (Directed by Chief of Bureau), I. isle Morrison. Assistant in General Charge. Editor, .1. E. Rockwell. Chief Clerk, .lames E. Jones. [Cir. l] 2 ' ONTENTS. Introduction Sulphur as a i The Belf-boiled lime-sulphur mixture I'" paral ion i i the mixture Apple bitter-rol experiments 8 Experiments in the treatment of other apple diseases 11 \ !>(•!- blotch Apple leaf-spol .„ Apple scab [2 Experiments in thi treatment of peach diseases 19 h brown-rol and scab |., Peach-leaf diseases ,,. bined fungicide and insecticide li; Range of possible usefulness r [Cir.l] 3 ILLUSTRATIONS Page. Fig. 1. Crop of apples from a Ben Davis tree sprayed three times with self- boiled lime-sulphur mixture JO 2. Crop from an untreated Hen Davis tree in the same i irchard as that sip >wn in figure 1 11 [Cir. 1] A n. r. i SELF-BOILED LIME-SULPHUR MIXTURE AS A PROMISING FUNGICIDE. INTRODUCTION. The well-known toxic action of Bordeaux mixture <>n peach Foliage, which renders ii pracl icallj useless for the control of peach diseases in the growing season, led the writer to investigate other possible fungi- cides that mighl prove less caustic. Moreover, Bordeaux mixture, although remarkably beneficial in the control of fungous diseases, even stimulating the ^rr< > \\ 1 1 1 of plants in addition to its fungicidal effect, is unfort unaleh often injurious to the fruit and foliage of the apple ami some other plants. The fruil russeting and foliage injury caused by Bordeaux mixture in the case of the apple ha- Keen the subject of much complaint in recent year-, thus increasing the demand for a fungicide t hat can he used on grow ing plant- u it hout danger of injury. 'The investigations of fungicide's in which various sulphur com- pound-, a- well as other substances, were tested, have extended over several years, bul no satisfactory results were obtained until last sea- son, when the self-boiled lime-sulphur wash was tried and proved to be sufficiently active to prevent fungous diseases without injuring the plain- treated. Although the results reported in the following p are exceedingly encouraging, it should he distinctly understood that this fungicide in the self-boiled form i- in ii- experimental stage and mi: t" the remarkable progress that has been made in the treatmenl "f plant diseases by fungicides, anything new in this field is <>i' the utmost importance and esthe i no- 1 can ■nil attention on the part of investi 1 fniit growers. This tls a new step in the use of sulphur as a fungicide Here we have for the first time a fungicide which apparently can In- safelj used "ii growing peach foliage. The susceptibility <>i peach foliage t<> injury by Bordeaux mixture and other coppi r utirely in prevenl their use in the treatment <>i peach 1 i pple ih' injurious effect in russeting the fruit and burning the has to a much less extent, but -i ill seriously, inn Tiercel with the otherwise suc- cessful use of copper. This situation makes the development of a fungicide which will obviate these difficulties of greal imp The results recorded are indeed remark- able and definite, 1ml inasmuch as they depend mi a single season's experimenl Scott has vi rly cautioned fruil growers against their general application until they are corroborated byfurther experiments. B. T G Physiologist ami < i b Ll ME -SULPHUR MIXTURE AS A FUNGICIDE. has not been sufficiently tested to justify its general recommendation. For the present, its use is advised for trial only, and the object of this preliminary paper is to show the rather striking results so far obtained and make them available to investigators and fruit growers as a basis for further experiments, in order that the value of the mixture may lie more speedily determined. The Bureau of Plant Industry will con- tinue the investigations, and it is hoped that at the end of another season definite recommendations can be made for the use of this wash or some modification of it in the treatment of orchard diseases. A similar self-boiled wash has some slight reputation as a dormant treatment for the San Jose scale, and a few fruit growers have used it rather extensively for this purpose, but it seems to have had very little consideration as a fungicide and has apparently never been recommended for use on plants in foliage. Curiously enough, how- ever, as early as 1833, before the general use of fungicides, Dr. Wil- liam Kenrick a recommended for mildew on grapes a mixture of sulphur (14 pints), quicklime (a piece the size of the fist), and boiling water (2 gallons). This mixture, after cooling, was diluted with cold water and allowed to settle. The clear liquid was then drawn off and diluted to make a barrel full before using. In 1885 William Saunders 6 also recommended for pear-blight a self-boiled lime and sulphur wash consisting of 8 pounds of sulphur and one-half bushel of lime with boiling water, the mixture to be applied as a whitewash with brushes; and for mildews he advised applications of the clear sulphur liquid drawn off from this wash and greatly diluted. SULPHUR AS A FUNGICIDE. Sulphur has long been known to have fungicidal properties and has played an important part in the treatment of several plant dis- eases, notably the grape powdery mildew, rose mildew, and aspara- gus rust. Previous to 1S80 it was almost the only fungicide in use, and it is to-day one of the best remedies for various mildews. In the form of potassium sulphid it has for years been the chief remedy recommended for gooseberry mildew and to a less extent for a few other diseases. The boiled lime-sulphur wash used as a dormant "The New American Orchardist, L833, p. 328. 6 Report, U. S. Commissioner of Agriculture, L885, pp. 43 and ii. cSince this article was prepared Prof. A. B. Cordley, of Oregon, lias presented in ihi' Rural New Yorker of March 7. 1908, p. 202, a summary account of his experi- ments in the use of dilute lime-sulphur sprays for apple scab, which sprays, made from the well boiled wash or from similar proprietary preparations, have also been tested on other fruit trees in foliage, such as the pear, peach, plum, prune quince, and cherry, and on grapevines. The results obtained werethoughl to point strongly to the conclusion that lime-sulphur solutions maj become a satisfactory substitute iui- Bordeaux mixture for summer spraying. [Cir. I I LIME SULPH I '; \ll\ ll RE \> \ II NGN [DE. < spray ranks close to Bordeaux mixture in the treatment of the peach leaf-curl and the California peach blight I Coryneum beyerincl'iiOxid.), a serious disease of the peach on the Pacific coast. < )n account of its caustic effect on the foliage of plants tliis boiled wash can nol be used during the l:i< »\\ i i i^r season and its usefulness as a fungicide is there- fore restricted to diseases thai can be reached in the dormant period; Ihii the self-boiled mixture used in the experiments reported in this paper was entireh uninjurious in the foliage and fruit of both the peach and I he apple. THE SELF BOILED LIME SULPHUR MIXTURE. At intervals during the pa>t several years the writer has made experiment- with sulphur ami various sulphur compounds with the object of finding a fungicide that could he used during the growing period on fruit trees, especially the peach, without injury t" the foliage or fruit. The first work was done in L901, at the suggestion of Mr. M. I>. Waite. and consisted of experiments with various sulphids, all of which proved injurious to peach foliage. During the season df L907 self-boiled lime-sulphur mixtures in various proportions and strengths were tested on both the apple and the peach. PREPARATION OF THE MIXTURE. The mixture that u r a\e the most promising results was composed of in pounds of sulphur . flowers or flour) and \~> pounds of fresh stone lime to 50 gallons of water," and may be prepared as follow-: Place the lime in a 50-gallon barrel and pour a l' or 3 gallon bucket of boiling water over it. Immediately add the sulphur and another bucket of hot water. The heat from the slaking lime will boil the mixture \iolently for several minutes. Some stirring is necessary to prevent burning, and more water should he added if the mass gets too thick to stir, but the cooking is more effectual when the minimum quantity of water i- used, usualh From 6 to s gallons being required. A piece of old carpet or gunnysack thrown over the top of the barrel helps to keep in the heat. The boiling will continue from twentx to thirty minutes, depending upon the quality of the lime. When the boiling ceases, dilute with cold water to make oil gallons, stir thor- oughlj and strain through a sieve of aboul 20 meshes to the inch in order t.> lake oul coarse particles of lime, hut all the sulphur should be carefulh w orked i hrough. • n a similar manner, enough for L50 gallons ma\ he prepared in a barrel by n-im: 30 pounds of sulphur and \.~, pounds of quicklime, with aboul 20 gallon- of boiling water. When the boiling ceases, the barrel should he filled with cold water and diluted with Inn gallons more when transferred to the spraj tank. ge 18. I fir. n 8 LIME-SULPHUR MIXTURE AS A FUNGICIDE. In some of the experiments a wash consisting of 5 pounds of sul- phur and 10 pounds of lime to 50 gallons of water gave excellent results. This would indicate that a much more dilute mixture than the 10-15-50 formula may prove to be a satisfactory fungicide. The wash was also prepared with cold water instead of boiling water, and in some cases a portion of the lime was at first withheld and later added, a small lump at a time, in order to prolong the boiling; but the experiments have not yci been sufficient to determine definitely the correct formula and the best method of preparation. Should the boiling he very prolonged the mixture might become caustic enough to burn foliage, although no such injury developed in the experiments. If it should be found in practice that the use of hot water dissolves too much sulphur, so that the foliage is injured, cold water may be substituted and a less intense heat thus developed, or the sulphur can be withheld until the lime has partly slaked, thus regulating the amount of sulphur dissolved. By this boiling process the sulphur is put in good mechanical con- dition for spraying, and enough of it is dissolved to make the mix- ture adhesive. As a large percentage of the sulphur is simply held in mechanical mixture with the lime water, it is necessary that the spraying outfit be provided with a good agitator, so that the mixture may be kept constantly stirred, and settling be thus avoided. In the treatment, of apple trees, Paris green may be added for the con- trol of the codling moth in the same manner as when Bordeaux jnix- ture is used. APPLE BITTER-ROT EXPERIMENTS. The work on apples was done at Bentonville, Ark., and the prin- cipal disease involved was bitter-rol (Glomerella rufomaculans (Berk.) S. and v. S.)- This disease began to appear in the orchard of ('apt. George T. Lincoln on July 8, 1907, and on July 12 the w riter, assisted by Mr. James B. Rorer, sprayed a block of 2-1 trees with this lime- sulphur mixture, adding 6 ounces of Paris green to each 50 gallons: a second block of 21 trees with the same mixture, substituting 2 pounds of arsenate of lead for the Paris green, and a third block of about 100 trees with Bordeaux mixture (5 pounds of bluestone and 5 pounds of lime to 50 gallons of watei i and arsenate of lead. A block of 24 trees was left untreated as a check. About half of the trees in each block were Ben Davis and the other half (livens. These 1 real incuts were repeated on July 26 and again on August 27, 1907. When the first application was made (July 12) some bitter-rot was showing on both varieties, as manj as fifteen or twenty affected fruits being found on a number of individual trees. Although the season was comparatively dry, the showers that came at rather long [Cir. 1] LIME-SULPHUB -MIX I i R] \s A FUNGICIDE. 9 intervals permitted of Infections sufficient to destroy a l;u •_:.' portion of i he crop on i he urn reated i pees. The crop of Ben Davis apples was picked on September 17 and L8, ami the Givens on October in. The apples, including the windfalls, from several average trees of each plol were sorted with reference to bitter-rot into diseased and sound fruit. The results are shown in Tables I and 1 1. Table I. -I/'/'''' bitter-rot ■■>• Ben Davis trees Comparative results from treatment with lime-sulphur mixt Bordeaux mixture, andfrcin checks. Trees spri 1 July 12 and 26 and August 27, 19 Number of sound apples. Number of dis- eased Percent- age of sound fruit. Lime-sulphur mixture: 1,651 510 1,256 791 572 215 142 164 40 98 29 52 lis 1,055 611 90 96 ■ Mo. ."> 92. 02 i\ mixture: 96. 16 Mo 8 Trees not sprayed: eh., k( Check D • ( heck i Although bitter-rol \\ as severe enough on the Ben Davis trees to destroy from 80 to 90 per ceni of i lie crop on the unsprayed trees, the lime-sulphur mixture held it down to less than 1(1 per cent of the crop, as shown in Table I. See also figures 1 and 2. In this experiment the sulphur wash compared favorably with Bordeaux mixture, the latter giving only slightly better results. The disease had a considerable start on the Ben Davis trees before the first ap- plication was made, and this accounts for at least a part of the diseased fruit on the sprayed trees. Slightly better results with both the sulphur and the copper treatments could probably have been secured had the first application been made a week earlier. Table 11. .1/'/'''' bitter-rot on Givens trees. Comparah .from treatment lime-sulphur mixtun and Bordeaux mixture, and from checks. 1 rees sprayed July 2 and -''i and August 27 1907. Number of sound Number oi 1 r.-. V. ;t Bordeaux mixture: Mi ' Mo . a s'i [2 Tree No '■ '."1. 10 Trees n •! sprayed: Check \ Check i ■ :>7 7'i 50219 rii. l ..s 10 LT.ME-SULPHUR MIXTURE AS A FUNGICIDE. Bitter-rol was nol so had on the Givens as on t he Ben Davis trees, but somewhat more than half of the crop on the unsprayed trees was destroyed by it, while the fruit sprayed with the lime-sulphur mix- ture, as well as that sprayed with Bordeaux mixture, was only slightly affected. It would appear from these tables that the two fungicides are equally effective against bitter-rot and that when desired the lime- sulphur mixture may be substituted for Bordeaux mixture in the treatment of this disease. These results show that the self-boiled lime-sulphur mixture is an excellent fungicide under the conditions attending this experiment. The only question that remains is FIG. 1. — Crop of apples from a Ben Davis tree sprayed three times with self-boiled lime-sulphur mixture. The sound fruit (92 percent) is in the pile on the ground and the fruit affected with bitter-rot is in the baskel whether it will maintain this high standard under more unfavorable conditions, such as extremely wet weather. So far as the writer could observe, absolutely no injury to the fruit or foliage developed from the use of this wash, and it adhered almost, if not quite, as well as Bordeaux mixture. At picking time the foliage was still white with the mixture and the fruit had a good coat of it. Again, however, it must be remembered that the sea- son was comparatively dry, the rainfall for July being only 0.81 inch and for August 3. 70 inches. Although the mixture seems to he quite adhesive, heavy heating rains might take il oil' the fruit and foliage, so that a large pari of its fungicidal value would he lost. [fir. 1] l.i A 1 1. Ml. I'll IK M :\ I i 1:1: \> \ FUNGH [DE. 1 1 EXPERIMENTS IN THE TREATMENT OF OTHER APPLE DISEASES. APPLE BL< 'I ( II Another experiment was conducted on 1 > < ■ 1 1 I>a\i^ trees in the orchard of Mr. Jefferson. The principal disease involved was apple blotch (Phyllosticta solitaria K. and E.). Both the lime-sulphur and Bordeaux mixtures were used here, as in the Lincoln orchard. Owing to unavoidable ilelaj s the firsl application was nol made unl il June 1 I . 1 90 7. when i lif disease had already gained ;i good foothold. A second application was made on July R. The fruii on the trees sprayed with the lime-sulphur wash, a^ well as thai sprayed with Bordeaux mixture, li<, -' i rop from an untreated Ben Davis tree in the same orchard as that shown in Ogurel. The frui l affected with bitter-rol (90.5 per cent I is in the pile on the ground and the sound fruit is in the b held up withoul further infection, while the checks continued to go down until practically the entire crop was destroyed by this disease. This is hardly sufficienl evidence to justify the conclusion thai the apple blotch disease will readily yield to the lime-sulphur treatment, luii these results stronghj indicate as much. Nil apparent injury whatever resulted from the use of the self- boiled wash in this orchard. However, a wash consisting of 3 pounds of sulphur and 5 pounds of lime to 50 gallons of water, boiled 15 minutes, when applied to a few apple tree- burned the leaves consid- eralil\ and caused some defoliation, showing that the boiled mixture is unsafe for use on apple foliage. [Cir. 1| 12 LIME-SULPHUR MIXTURE AS A FUNGICIDE. APPLE LEAF-SPOT. In both the Lincoln and the Jefferson orchards the foliage on the trees sprayed with the lime-sulphur wash did not become affected with the leaf-spot disease (Sphaeropsis maZorum Pk.), except from some early infections that took place before the treatment was made. The leaves on these trees remained fresh and green until frost. On the other hand, the unsprayed trees left as checks were partly defo- liated a month or more before the normal period of leaf fall. It appears, therefore, that the leaf-spot disease may be readily pre- vented by the use of this lime-sulphur wash. APPLE SCAB. Very little scab (Venturia inaequalis (Cke.) Adh.) occurred in either orchard, and no definite data on the control of this disease were obtainable. The results with bitter-rot, however, were so excellent as to indicate that similar success with this wash might be expected in the treatment of apple scab, and perhaps pear scab as well. Bor- deaux mixture has been so efficient in the control of scab that it would seem undesirable to replace it with another fungicide except to avoid the russeting of the fruit and the foliage injury often following its use. EXPERIMENTS IN THE TREATMENT OF PEACH DISEASES." The work on the peach was done in the orchard of Ilitt Brothers, at Koshkonong, Mo., in cooperation with the Missouri Fruit Experi- ment Station, Messrs. F. W. Faurot and T. W. Ayres assisting. A block of 6-year-old Elberta trees was divided into 30 plots of 5 trees each and several different mixtures in addition to the self-boiled lime-sulphur wash were tried. Bordeaux mixture used in several different strengths was so injurious to the foliage that it was mostly dropped from the experiment after the second treatment; sulphuric acid, 1 part to 1,000 parts of water, not only defoliated the trees but caused the entire crop of fruit to drop; and a lime-sulphur wash con- sisting of 11 pounds of sulphur and 3 pounds of lime to 50 gallons of water, boiled forty-five minutes, burned the leaves and partly defo- liated the trees. PEACH BROWN-ROT AND SCAR. The self-boiled lime-sulphur mixture heretofore described did not injure the peach foliage or fruit and proved to be a strong fungicide in its effect on both brown-rot and peach scab, as well as on some " In a paprr before the American Pomological Society, read mi September 25, 1907, the writer gave a summary of these experiments ami outlined the principal results obtained. [Cir. lj LIME-SULPHUB MIXTURE VS \ FUNGICIDE. 13 leaf diseases. Unboiled sulphur with milk of lime and pure sulphur suspended in water were also used with promising results. The treatments of the several plots of mosl interest and the results on brown-rot {Sclerotinia fructigena (P.) Schrt.) and seal), or black- spot (Cladosporium carpophilum Thiim.), arc condensed in the fol- low ing i able: Tumi III Treatments awl results of experiments obta gicides on rot and scab of peach. Mixtures used. of spraying, I'.hit. Total fruits. affected with brown-rot. lies Plot. 22 22 22 22 June June. July. affei ' with • 1 2 Lime-sulphur self Llme-sulph I self- fi 6 6 20 ■Jii 20 20 10 :. 5 5 5 5 2 -' 2 13 13 13 13 13 13 No. 1,329 1,574 1,132 1,356 No. • 250 220 212 507 381 1,444 P. Ct. 14 30 is. 7 19.8 37. 4 21.2 7:i. 3 No. P.ct 5ii 4. 3 227 i - Sulphur and lime milk Sulphur water I in SO) sulphur -In 15 .'in .self- boiled . . . Liime-sulpl boiled in" 11 X 4 90 24 boiled .... 523 27 728 40. "> i 10 urn reated i rees 28. 1 o in pounds of sulphur and 15 pounds of quicklime to ."iii gallons of water. Plot l. as shown in the foregoing table, was sprayed five times with a self-boiled lime-sulphur mixture composed of H» pounds of sulphur and 15 pounds of quicklime to 50 gallons of water, prepared in i he same manner as described on page 7. The trees were spraj ed on Ma\ 22, June 6, June 20, Jul} 5, and July 13, 1907, the last dale being about two weeks before the fruit matured. The crop was picked from .Inly 30 to August 7. and the five trees yielded 1,329 fruits, 10.4 per cent of which were affected with brown-rot. This seems rather encouraging when 73.3 per cent of the crop on the check trees in adjacent rows rotted. Moreover, only !.."> per cent of the crop showed nn\ marks of scab, and mosl of these were ver\ small, almost unnoticeable specks. Mr. Ayres, who was on the ground constantly, reports that the leaves showed no injury at any time dur- ing the season-, and when the writer made a final examination on August 27 the foliage was still green and apparent!} uninjured. The mixture had adhered so well that the leaves and branches were whit ish on t hat dale. l'lot 2 had the same treatment as plol I. except thai the formula in this case w.-i^ reduced to 5 pounds of sulphur and 10 pounds of lime to 50 gallons of water. The results were about the same a-- in the firsl plot, 10.3 per cenl of the crop being affected with brown- rot and 9.3 per cent with scab. The foliage was uninjured and the [Clr. 11 14 LIME-SULPHUR MIXTURE AS A FUNGICIDE. mixture adhered well throughout the summer. This would indi- cate that a weaker mixture than that used in plot 1 may prove to be satisfactory, thus cheapening the treatment. Plot 3 was sprayed on the same dates as plots 1 and 2 with an unboiled sulphur and lime-milk mixture composed of 10 pounds of sulphur and 10 pounds of lime to 50 gallons of water. The lime was slaked in the ordinary way and the sulphur worked into it, forming a paste. Then the mixture was diluted to make 50 gallons. This mixture was more difficult to apply, required more agitation, and did not adhere so well. However, it held the rot down to 14 per cent of the crop and the scab to 6.9 per cent, indicating that it has con- siderable fungicidal value. Plot 4 was sprayed on the same dates as the three plots previously mentioned with 10 pounds of sulphur suspended in 50 gallons of water. The sulphur was worked into a paste and then diluted. The rot on this plot was 30 per cent of the crop, and the treatment for this disease was therefore practically a failure. However, only 3.4 per cent of the fruit was affected with scab. The sulphur with- out the lime seems to have been entirely sufficient to control this disease. Sulphur settles readily in water and is rather difficult to keep in suspension. Plot 20 was sprayed with the. same self-boiled mixture as plot 1 , and the applications were made on the same dates, except that in this case the first application (May 22) was omitted. The percentage of rot, 18.7 per cent, was rather high, owing apparently to the omission of the May treatment. However, only 8.8 per cent of the crop was affected with scab. A few scab infections had taken place before the treat- ment was begun, and on unsprayed trees this disease developed quite rapidly after the middle of June. Plot 23 was sprayed on July 2 and 13 with the same self-boiled mixture used on plots 1 and 20, only two applications being made. Of the crop, 19.8 percent rotted and 29.4 per cent was affected with scab. The fruit was already badly "scabbed" before the treatment was begun, and the cracking due to this disease opened the way for brown-rot. Plot 24 was sprayed on July 2 with the same mixture as plots 1 , 20, and 23. Only one application was made, and it was quite insufficient for both brown-rot and scab, 37.4 per cent of the crop being affected with the former disease and 38.6 per cent with the latter. Plot 27 was sprayed with Bordeaux mixture consisting of 1 pound of copper sulphate, 5 pounds of lime, and 50 gallons of water. The applications were made <>n duly 2 and 13, with the result that 21.2 per cent of tin' crop was affected with brown-rot and 40.5 percent with seal). The treatment was entirely too late for scab, but had some [Cir. 1J l.i mi SI i.l'liri; MIX i i 1:1 ISA Fl NGK IDE. I 5 effect on brown rot. These results were aboul the same as those se- cured on plol 23, which was sprayed on the same dates with the self- boiled lime sulphur mixture. The plots on w Inch spraj ing with Bor- deaux mixture was commenced on May 22, when the sulphur treat- ment was begun, were abandoned on account of severe foliage injur] . These plots, not having been carried through the season, are omitted from the table. On the check plot, consisting of 10 untreated trees located in rows adjacent to the sprayed rows. 73.3 per cenl of the crop was affected with hroun-rot and 28.1 percent with scab. A glance al Table III shows thai sulphur, wherever used in this experiment, whether self-boiled <>r unboiled, applied once or oftener, had more or less ell'ect on the brown-rot disease. Where the self- boiled wash of both full strength and half strength was used, nearly 90 per ccni df i lie crop came through U'cc from the disease. Owing, perhaps, to the late spring frosts, some of the peach pits cracked and there was considerable proliferation around them, which resulted in a cracking of the skin, thus exposing the fruit even on sprayed trees to brown-rot infection. This, together with insect punctures, partly accounts for the 10 per cent of loss on plots ] and*2. A comparison of these two plot- indicates that ."> pounds of sulphur in the mixture is just as good as 10 pounds, the larger quantity apparently being unnecessary. It must he understood that the writer does not consider this single series of experiments sufficient to justify final conclusions upon w Inch to base orchard practice. Not until these results have been verified under different conditions can the treatment he recommended with full confidence. It is not at all surprising that this sulphur mixture should be a good fungicide; the gratifying surprise is that it does not injure peach foliage. Under different weather conditions or when boiled with a more active grade of lime it mighl prove injurious, and for this reason caution should he exercised until further knowledge of its action is obtained. Although occasional rains occurred at Koshkonomr. Mo., while the experiment was in progress, the season would he considered rather dry. The rainfall there as recorded by the voluntary observer, Mr. John W. Ilitl. was as follows: For the month of May. L0.89 inches; June, L9 inches; and July, t .67 inches. Enough rain fell to produce considerable injury to peach foliage following applications of Bor- deaux mixtun a in I to cause a severe outbreak of brown-rot. During a\cr\ wet season, however, the treatment mighl not be so successful; in fact, this disease is influenced by so n\ factors that it seems doubtful whether an entirely satisfactory treatment for it will ever be [Cir. 1] 16 LIME-SULPHUR MIXTURE AS A FUNGICIDE. found. The plum curculio punctures the skin of a certain percentage of the fruit and thus admits the fungus in spite of all spraying that can be done; also, some of the leaf-footed plant bugs feed on the rotting and the sound fruit indiscriminately, thus undoubtedly distributing the fungus and perhaps even with their beaks inserting the spores be- neath the skin of the fruit. It seems quite impossible to protect against such infections: In the case of peach scab the results were very decided. In every plot where sulphur was used before infection took place, this dis- ease was almost completely controlled. Even sulphur suspended in water without the addition of lime seems to be sufficient to control this disease. As a rule, the seal) infections on the sprayed fruit were manifested in small specks instead of the large spots and cracks that were so common on the unsprayed fruit. PEACH-LEAF DISEASES. The frosty mildew (Cercosporella persicae Sacc.) was also con- trolled by the self-boiled lime-sulphur mixture (10-15-50). This was demonstrated especially on Picquet's Late, which variety was sprayed on July 26 and again on August 8. The writer examined the trees on August 27 and found the foliage in a vigorous, healthy condition, practically free from leaf diseases, while the leaves of the unsprayed trees were badly affected with the frosty mildew, had turned yellow, and were falling considerably. Some of these leaves were also af- fected with a shot-hole disease due apparently to Bacterium pruni Smith, but none of this could be found on the sprayed trees. A COMBINED FUNGICIDE AND INSECTICIDE. Self-boiled lime-sulphur washes used in the dormant spraying of fruit trees are known to have some effect against the San -lose scale, and in order to avoid the expense of a cooking plant a few growers have employed this method of preparing the wash. Entomologists have wisely discouraged the use of self-boiled washes because of their inferiority to the boiled preparations, but when used as a fungicide in the growing season a self-boiled lime-sulphur wash might be ex- pected to aid considerably in the control of the San dose scale and other scale insects by the destruction of the crawling lice, and would thus perhaps prevent the infestation of the fruit, a condition espe- cially likely to occur witli apples and pears. This would give it a decided advantage over Bordeaux mixture and make it especially useful as a combined fungicide and insecticide in the treatment of large apple trees on which (he scale is so difficult to control. Summer applications for the prevention of fungous diseases would thus sup- [Cir. 11 l.i. Ml SULPHUB MIXTURE \s \ FUNGICIDE. 17 plement the dormanl treatmenl of the San Jose scale withoul extra cost. Sulphur is also a well-known remedj for various mites, and the self-boiled wash would probably be "I' considerable value in the conl rol of the red spider. RANGE OF POSSIBLE USEFULNESS. Tlic fungicide described in these pages i- only in the experimental stage, and it is impossible to predicl the extenl of iis usefulness; but if it will control apple bitter-rot, a- the results so far obtained indi- cate, ii would naturally be expected to prevent apple scab. Al- though no positive results were obtained with this disease, the indications were that it might easily be controlled with the bme- sulphur wash and the fruit russeting and foliage injury duo to the use "\' Bordeaux mixture thus avoided. Except the injury follow- ing it- use in a wet season, Bordeaux mixture furnishes an entirely satisfactory fungicide for both apple -call and bitter-rot, perhaps better than can he expected of th • lime-sulphur wash; but the latter ha- the advantage of being a combined insecticide and fungicide and does not injure the fruit or foliage, or at least ii would so appear from these preliminary experiments. This self-boiled mixture could reasonably l>e expected to readily control the powderj mildews of fruit, some of which have long been known to be preventable by the application of sulphur in some form. Owing to its greater adhesiveness, it should perhaps largely supplant drj sulphur and liver of sulphur in the treatment of various mildews. If the results of last year's experiments are borne out by further tests, the most important function of tin- fungicide will doubtless be the control of peach diseases. Heretofore, practically no known fungicide could he used on peach foliage without injurious results, and for tin- reason orchardists have been unable to combat some of the more important peach diseases ami to prevent the annual loss of several millions of dollar-' worth of fruit caused by them. Bor- deaux mixture, the standard fungicide, can not be used <>n peach tree- during the growing season without danger of serious injury to the foliage. While a weak Bordeaux mixture may he used in a drj season without injurious results, the same mixture applied in a wet season, when mosl n led. will usually defoliate the trees. The other forms of copper, such a- a m nioniacal copper carbonate and acetate of copper, are even more toxic than Bordeaux mixture. It is apparent, then, that an efficient cheap fungicide thai can be used on the fruit and foliage of the peach withoul injurious results will be of inestimable value. The self-boiled lime-sulphur mixture give) promise of ting these requirements, and it is hoped that [CIr. 1] 18 LIME-SULPHUR MIXTURE AS A FUNGICIDE. the results already secured will be substantiated by further investi- gations. Under some unfavorable weather conditions injury to the foliage or fruit might possibly develop, and heavy beating rains might wash the sulphur away, so that its fungicidal effect would be partly lost. It seems likely, however, that a lime-sulphur mix- ture, either self-boiled or unboiled, will prove to be a safe and val- uable fungicide for use on fruit trees and other plants during the growing season. Approved: James Wilson, Secre tary of Agricultv. re . Washington, D. C, March 14, 1908. Note to the Second Edition. — Since .the first edition of this circular was issued, additional results of the season's work of 1908 have become available, particularly the results of experiments in spraying the peach at Marshall ville, Ga. It has been found that too much sulphur was brought into solution when hot water was used in slaking the lime, especially when material sufficient for 200 or 300 gallons was made up at one time. Under the warm, rainy, humid conditions that occurred at one period in Georgia some injury resulted to the peach foliage, there being enough soluble sulphids in the solu- tion to burn the leaves. When cold water was used in slaking the lime, only a small quantity of sulphur is actually brought into solu- tion and no harm, or a very insignificant amount, occurred. For use Oil the peach and Japanese plum, therefore, cold water instead of hot water is advisable for slaking the lime. Furthermore, it was found that 5 pounds of sulphur to ."1 pounds of lime is entirely sufficient for spraying peach trees, so that this for- mula is now recommended. Where the precaution of mixing with cold water was taken no injury to peach foliage resulted. On the apple the stronger mixture made with hot water can be used. It is doubtful, however, whether more than 8 or 10 pounds of sulphur and the same quantity of lime need be appljed on the apple for the best results. [Cir. 1.] o UNIVERSITY OF FLORIDA 3 1262 09217 8937