WWTAL CONTROL or snow Am (W sans mar OF GOLF Games In mummy: mm M {Niko PM! 05.5%. S. “€3me STATE Cfim James C. Myer“; 3:. 1953 Date This is to certify that the thesis entitled 'prorinnul Control of Snow I011. mm; 0P. on Golf Green hr! in lea-thorn lichigan' presented by Juno. 0. were, Jr. has been accepted towards fulfillment of the requirements for _'_°_§_ degree in m M Major professor “LIL 22; 1953 EXPERIMENTAL CONTROL OF SNOW MOLD (TYPHULA SP.) ON TURF OF GOLF GREENS IN NORTHERN MICHIGAN B y James C. killers, Jr. A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Botany and Plant Pathology 1953 . \w“ I i '1' ll Ill I! II" II ll . .‘II III In] [I III THESIS 'fr:*§rwc;: (7‘. ACKNOWLEDGMENTS The a* .or wishes to express his sincere gratitude and thanks to Dr. John R. Vaughn, formerly Associate Professor of Pathology in the department of Botany and Plant PathOIOgy, Michigan State College, under whose guidance and sympathetic encouragement this investigation was conducted. He also wishes to extend his appreci- ation to Dr. William B. Drew, Head, Department of Botany and Plant Pathology, Michigan State College, Dr. Donald J. deZeeuw, Assis- tant Research Professor and Dr’. Charles L. Gilly, Assistant Pro— fessor and Curator, for their c00peration and assistance in the final preparation of this thesis. Appreciation in also expressed to Al Lagman, greenskeeper at Blaney Park, to Ante Piraiinen, greenskeeper at Sault Ste. Marie, and to Edward Rudd, Sr., greenskeeper at Cedarville, Michigan for c00peration in making observations and reporting information on the experimental plots during the summer months when these could not be personally inspected. In conclusion, an acknowledgment of appreciation is due the United States Government and the Veterans Administration for finan- cial aid furnished through Public Law No. 346. ii 308883 VITA James C. Myers, Jr. candidate for the degree of, Master of Science Final examination: July 22, 1953, 10:00 A. M., Room 450, Natural Science Building (Botany and Plant Pathology Seminar Room) Dissertation: Experimental Control of Snow Mold, (Ty phula sp.) 0.1 Turf of Golf Greens in Northern Michigan Outline of Studies: Major subject: Plant Pathology Minor subject: Education Administration Biographical Items: Born, May 31, 1917, Bloomington, Illinois Undergraduate Studies, Illinois Wesleyan University, Bloomington, Illinois, 1935-1939 Graduate Studies, Michigan State College, summer sessions of 1950—1953, inclusive Experience: 1. Teacher of Biology, and Athletic Coach, Morris High School, Morris, Illinois, 1939-1942 2.. Teacher of Bi010gy and Assistant Athletic Coach, Benton Harbor High School, Benton Harbor, Michigan, 1942—1944 iii Member of United States Naval Reserve, 1944 to present; Officer IndoctrinatiOn taken at Camp McDmmugh, Plattsburgh, New York, 7 weeks, Summer 1944; commis- sioned Ensign, U.S.N.R.; active duty in South Pacific--Leyte, Phillipines, Okinawa, and Japan, 1944—1946; released to inactive reserve with rank of Lieutenant junior grade, U.S.N.R., 1946 Associate Professor of Physical Training and Director of Athletics, Sault Ste. Marie Branch of the Michigan College of Mining and TechnolOgy, 1946 to present iv I l n l I III l l lira] ll llrl [ .lIIII-Il l .l TAB '_.E OF CONTENTS INTRODUCTION ............................... The Host ................................. The Diseases ............................... Symptoms of Snow Mold Disease ................. Economic Importance of Snow Mold . ............. REVIEW OF LITERATURE ....................... MATERIALS AND METHODS ...................... Selection of Experimental Sites .................. Field Study Methods .......................... Laboratory Study Methods ...................... EXPERIMENTAL RESULTS ....................... Results of I‘ield Studies ....................... Blaney Park experimertal site ................. Cedarville exPerime--tal site .................. Sault Ste. Marie experimental site .............. Results at the three locations ................. Results of Laboratory Studies ................... DISCUSSION ................................. l l I I‘.fl l l I l ‘l Ill I'lllllllrl ll I'll! I i '1'. l I I nil . u l I . l t .. I . [rial I . H‘ I " I ll [ [ l 'l I III . ll . .I 4 oooooooooooooooooooooooooooooooooo LITERATURE CITED ........................... APPEN. DIX .................................. 49 51 53 f .IST Oi“ TAB- ,ES Page I. Strengths of fungicide concentrations (weight of fungicide/volurne of water) utilized in field experiments ................ . .......... 17 II. Summary of dates of autvmiial spraying and sprirg observation, during course of field experiments . . . . 19 III. Total snowfall, as recorded at weather statio:--.s nearest each experimental site, for tie years 1950-1953, inclusive ........................ 20 IV. Summation of all data obtained by field observations on the effect of five furgicides in cox-ztrol of snow mold disease at four localities in Michigan ....... 5'? V. SummatiOn of all data obtained by lab-oratory observa— tions on the inlai‘nitior. of radial growt': of the snow mold pathogen by the five fungicides ........ 58 3’ . vii U1 10. ll. 12. LIST OF -WIGURES Diagram of eastern upper pe:-.ir:_sula of Michigan showing expe rimertal site 5 ................... Diagrams of eXperimental plots at all sites for years 1950-1953, inclusive ................... Percentage Green 3 . Percentage Cedarville, Percentage Green 3 . Percentage of control at Blaney Park. ooooooooooooooooooooooooooooooo of control at Les Cheneaux Club, Michigar. Green 3 ................ of control at Sault Ste. Marie. OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO of control for all three greens for three years ........................... Growth of Typhula sp. in media of 100 ppm. of all five fungicides ......................... Growth of Typhula sp. in media of 100 ppm. of all five fungicides ......................... Growth of Typhula sp. in media of 250 ppm. of all five fungicides ......................... Growth of _T_yp hula sp. in media of 500 ppm. of all five fungicides ....................... 4’. '. Photograph of green number 3 at Blaney Park, showing depressed area with typical mottlin and coalescence of infection Spots .............. Photograph of green number 3, Blaney Park, showing large infection area .................. viii 23 23 24 24 27 28 28 34 34 13. 14. 16. 17. 18. 19. Page PltotOgraph of green number 3 at Blar ey Park; a close-up of area attacked by Tvp'nula sp. ........ 34 Photograph of green x..urnbcr 3 at Les Cheneaitx Club. Cedarville; close—up showing typical coalescence of the irfectioz‘. areas .............. 38 PhotOgraph of green number 3 at Les Cheneaux Club, Cedarville; close—up showing white, flossy, wool— like mycelium of Typhula sp. ................. 38 PhotOgraph of green number 3 at Les Cheneaux Club, Cedarville; close-1p of c0rrtrol area showing the infection pattern of Typ‘nula sp. ............. 38 Photograph of greed number 8 at 500 Country Club, Sault Ste. Marie; early stages of infection by Typhula sp. 0.: untreated green ................ 42 PhotOgraph of green. :urnber 3 at 500 Country Club, Sault Ste. Marie; close-up of mycelium mat 0.1 the control area showing typical "gummy" appearance at this stage of development .......... 42 Photqgraph of green number 3 at 500 Country Club, Sault Ste. Marie; control area showing large dried patches of infectious material on the surface of the green ........................ 42 ix INTRO DUCTION The incidence of "winter—kill" and its obvious severity on the putting greens of approximately fifty golf courses in the upper peninsula of Michigan were noticed three years ago by the author. Upon inquiry, it was found that nothing was being done by the greenskeepers to combat the pathogen responsible for the destructimx of the gree:-..s. There are several diseases that attack the bent grasses grown on golf greens. Under certain conditions these diseases may be so severe as to produce extensive damage to, or even complete killing of, the turf. It is known that in some years the diseases may be very serious. and cause extensive damage, while in other years there may be practically no damage. Such differences are usually associated with variations in the weather conditions from “‘ year to year. Temperature and moisture apparently play a major role in the incidence of the known turf diseases. The purpose of this problem was to determine the identity of the pathogen responsible for the damage, and to assess the potential control, or inhibition, of the disease by a number of fungicides. The preliminary work was started in the autumn of 1950, and the research prOgram was carried on for the following three years in the belief that over such a period of time most of the materials used would show definite patterns of control in relation. to the varying climatic conditions. The Host Bent grass putting greens are in use in nearly every section of the United States, and the bent grasses used for this purpose 1 (varieties of Agrostis pa_lu_stris Huds. ) are susceptible hosts to many turf diseases. South German Bent was one of the first varieties to be used for golf putting greens in this country. World conflict in 1914 made it impossible to secure adequate supplies of The binomial here used for the creeping bent grass is the one accepted by Hitchcock and Chase (14) in Edition 2 of "The Man- ual of Grasses of the United States," published in 1951. Fernald (9), in Edition 8 of "Gray's Manual of Botany," published in 1950, sub- ordinates the creeping bents as a variety under the redtop, and re- fers to them as Agrostis alba L., var. palustris (Huds.) Pers. Glea- son (10), in "The New Britton and Brown Illustrated Flora . . .," published in 1952, obscures some of the creeping bents and the red— top as varieties of the European stoloniferous bent, and places the remaining creeping bents in a separate species; the creeping bents, therefore, are referred to by Gleason as Agrostis stolonifera L., var. comEcta Hartm., and as A. tenuis Sibth. I‘llll'lilllliil. the seed of this particular grass. Consequently, the Greens Section of the United States Golf Association fostered the selection and prop— agation of new strains of bent grass. Present-day plantings of se- lected creeping bents are the result of such research. Almost all of the bent grasses now used on putting greens are susceptible to a number of turf diseases, although some of the most recent selections have proven to be more—or-less resistant to at least some of these diseases. The close—cropping of the greens 8.2“d the resultant density of foliage, tOgether with the usually abundant moisture and high temperatures of the greens' surface produces conditions ideal for infection and extensive spread of the causal pathogens. The Disease 5 Diseases commonly found on the golf greens of Michigan ac- cording to Howard (16), are: Brown Patch, Pellicularia filamentosa (Pat.) ROgers (Rhizoctonia solani, Kuhn); Dollar Spot, Sclerotinia homeocarpa F. T. Bennett; Melting—out, Curvularia geniculata (Tracy and Earl) Boldijn; and Snow Mold, Typhula itoana Imai. Isolations of all these diseases have been made from Michigan greens by Drs. John R. Vaughn and William Klomparens when at Michigan State ‘ ‘llll'l.l|lllllllllldl |.I 4 College. The identification of the organism considered in this thesis was confirmed by them. Symptoms of Snow Mold Disease The injury caused by Typhula occurs either under the snow or as the snow is melting. The visible damage begins as a blotchy circular area one-half inch to two inches in diameter. The fungus spreads radially as a band or ring of white, blue—gray, or some— times alrnost black mycelium approximately one inch in width. The mycelial mat is often filled with small reddish-brown or dark—Turown sclerotia. Damage usually ceases when the area reaches a diameter of one or two feet because of the drying-out or warrning-up of the turf surface. However, the patches of infection have been known to coa— lesce and cover an area twenty feet in diameter. After the snow melts, the leaves of the host grasses die, and become grayish-white on drying. Finally, the leaves become matted tOgether on the ground. Economic Importance of Snow Mold The losses from snow mold in Michigan are difficult to exti- mate. In some years there is little or no loss, while in other years the damage is extremely severe. For example, in the United States there are approximately six thousand golf courses occupying approxi— mately 750,000 acres of land. The investment in land, buildings, machinery, playing equipment, and other necessities, and the labor required for maintenance of the courses makes golf a multimillion dollar sport. As it is quite obvious, this sport is all dependent up- on grass. The regulation golf course has eighteen holes, by tradition, but often many have only nine. These holes, of course, are lo- cated on the greens. Putting greens represent one of the most highly specialized uses of grass. Without an excellent turf on the greens to provide a keen putting surface, golf would not be the pop- ular sport it is today. It might be noted, here, that many golf courses have recently abandoned bent grass greens in favor of such substitutes as oiled sand greens because of the inability of the greenskeepers to c0pe with pathOgenic problems. Even the high-score golfer is aware that such substitut greens are decidedly inferior to the tr:.1ditio*.al '5 st greens. REVIEW OF LITERATURE An investigation of the available literature with respect to snow mold on turf and other grasses showed that relatively little research and few papers had appeared on this subject. Imai (17), in 1936, reported and described a disease of grasses in Japan caused by an organism which he named and described as Typhula itoana Imai. Other reports and observations of this disease, as it affects various grasses, are by W. H. Davis (6) and Remsberg and I-im-gerford (22) in 1933, Vang (26) in 1937, Ekstrand (7, 8) in 1939, Remsberg (21) in 1940, Noer (20) in 1944, Blodgett (2), Brundza (4) and Vang (27) in 1946, Westcott (31) in 1950, Howard (16) in 1951, Meiners (18) and Sprague (23) in 1952, and Holton (15) in 1953. A nmnber of these papers refer Specifically to the presence or the effect of a snow mold organism (Typhula sp.) on the bent grasses used in the turf of golf greens. Remsberg (21) decided that the pathogen she was studying was Typula itoana Imai, and states that it "occurred most frequently under deep and drifted snow, and in areas where the snow was slow and delayed in melting in the spring," although Vang (2.6) had earlier suggested that the damage occurred only at the time of snow melt. 6 During the year prior to Remsberg's report, Ekstrand (7, 8) had sug— gested that "infection probably takes place to a considerable degree through the soil." Remsberg and Hungerford (22) had previously re- ported that the snow mold organism (or organisms) reacted very dif— ferently to variations of temperature apparently associated with changes in depth of snow cover; they stated that Optimum growth oc— cured at 10° Centigrade and that growth appeared to cease at and above temperatures of 25° Centigrade. 1n evaluation of the papers mentioned in the preceding two paragraphs, all that can be said honestly is that very little really is known about the etiOIOgy of the snow molds, of the conditions which infection occurs and in which subsequent epidemic development takes place. A number of fungicides have been used, primarily in an ex- perimental manner, in an attempt to control or inhibit the develop- ment of the snow molds and other turf diseases. The most impor- tant of these, on the basis of literature reports, seems to be cyclo- heximide (known in the trade as Acti-dione). Among those who have reported upon the effects of this particular fungicide are: Got- tlieb, Hassan, and Linn (11) and S. H. Davis, Engel, and Silber (5) in 1950, Vaughn (28) and Nelson (19) in 1951, Meiners (18) and Vaughn and I‘flomparens (29) in 1952, and Holton (15) in 1953. Other reasonably effective fugicides were discussed by Wernham and Kirby (3) in 1943. In some of the essentially preliminary reports on Acti-dione, it was intimated that this particular fungicide is very potent in its effects, but none of the authors mentioned above suggest any basis for such. potency. Recent work, on an essentially empirical basis, involving the effects of Acti-dione on cellular structure and organization and On nuclear response have been reported by Hawthorne (12) in 1951, Haw— thorne and Wilson (13) and Thanos (25) in 1952, and Bowen (3) in 1953. In brief, these workers indicated that the effectiveness of Acti-dione as a fungicide may be due to intracellular effects such as mitotic irregularities, failure of cell-wall formation and resultant cessation of cell multiplication, and chromosome aberrations. Even in very low concentrations, Acti-dione causes cessation of both cell multi- plication and cell expansion, with the resultant "death" of parts of organisms or entire organsims. The relatively small number of papers discussed above, and included in the section on Literature Cited, may be explained by the comparatively short time that pathologists really have been interested in turf diseases. Also, the recent availability of Acti—dione and similar antibiotics and fungicides for experimental disease control is reflected in the same manner. MATERIA-’ .8 AND METHODS Selection of Experimental Sites Three golf courses were selected as being typical examples of the upper Michigan area. In 1950 the courses chosen were: (1) Portage Lake Golf Course, HOUgh‘L‘O'f'L, Michigan; (2) Blaney Park Golf Course, Blaney Park, Michigan; and (3) 500 Country Club Course, Sault Ste. Marie, Michigan. These courses were approximately 300 miles apart from one extreme to the other, and with such a range of climate it was felt that any results determined would be accepta- ble as fairly accurate for this area. The following years of 1951 and 1952, the Les Cheneaux Club of Cedarville, Michigan, forty miles south of Sault Ste. Marie, was substituted for the Portage Lake Golf Course at Houghton because of the uncertainty of weather conditions in the autmnn, when spraying of the greens was performed. While spraying the greens at Blaney Park in 1951, sudden heavy snows at Houghton made it impossible to continue the experimental work started there the previous year. As a matter of fact, the highways were blocked so that it was impossible to go to Houghton. 10 11 With the inclusion of the Cedarville golf course, a triangle of greens under observation was formed, with a forty-mile base from Sault Ste. Marie to Cedarville, and one hundred miles on the re- maining sides from Blaney Park to each of the other locations. The map in Figure 1 indicates the location of the golf courses. At each of these locations, One green was selected on the basis of its past history as the worst green, from the standpoint of "winter—kill," for the particular course. The greens so selected for the eXperimental work were: (a) green number 3 at the Blaney Park Golf Course, Blaney Park; (b) green nuInber 3 at the 500 Country Club; Sault Ste. Marie; (c) green number 3 at the Les Cheneaux Club; Cedarville; ((1) green number 9 at the Portage Lake Golf Course, Houghtoa. On each of the greens, plots of approximately equal area were marked out, the number dependent upon the number of fungicides to be tested in a particular year; one of these was designated as the control plot, while the remaining ones were used for applications of the selected fungicides. Plot technique was essentially that recom- mended by Struble (24). The greens selected for experiments at the three courses, as With standard greens in the area, were each approximately 6,000 12 Figure 1. Diagram of the eastern upper pe.:insula of Michigan, showing experimental sites. B = Blaney Park; C = Cedarville; H n Houghton; 5 :2 Sault Ste. Marie. 13 square feet in area. Tie individual plots sprayed i: 1950, W':€1\ Orly three fungicides were tested, were approximately 1,.‘100 sqvare feet i: area; it. tfie other two years, when five fungicides were used, tley were approximately 1,000 square feet in area. The gree~ s 11..der study were all of turf composed of (:.-'eepiz.g bent grass {Ag-rostis palustris), variety unknown, and was established turf at all locxztions. Five fungicides were closer for this experiment at t...e recom— mendation of Dr. John R. Vaughn; tuese were: ’1) Acti—diove (cycloheximide) (2) Calo-clor (mixture of mercurous— a:.d mercuric-chloride) (3) C8~zC 1025 (mixture of c0pper— , zi 1c- , cadmiurn— a_.d me rcur y - chlo ride) (4) Cadminate (cadmium succi'wate) (7')) Tersan (tetramethyl thiurarn disulpiide) In 1950, only the first three were used, but wiser: the re— maining two became available in 1951 they were added to the pro— gram for comparative purposes. The reason for tie selectiOn of the first of these fungicides was that an active prOgram for study of Acti-dione was in prOgress both at Michigan State College, rnder the auspices of the Upjoln Company of Kalamazoo, and elsewl:ere in the United States. "Calo—clor" and "C&C 1025" a:_d, subsequently, "Cadminate" and "Tersan" were chosen. as representative examples 14 of other available fungicides being marketed (or experimentally stud.- ied prior to commercial production) in competition with the Acti— dione. It seemed advisable to compare the effectiveness of t.-_ese five compounds in controlling the snow mold disease through con- trolled experimental work. The fungicides were applied to the plots with a standard Hud— son hand-punip sprayer equipped with a rnist-type nozzle. The same puznp and nozzle were used throughout all experimental work. In the experimental work carried out in the laboratory at Michigan State College during the summer of 1952, standard labora- tory equipment for inoculation and studies of pathOgen growth were utilized. Inoculurn for these studies was obtained at the Sault Ste. Marie site in the spring of the same year. This was cultured at Michigan State College by Dr. John R. Vaughn and Mr. William Klomparens, who determined the organism as T phula sp., probably closely related to, if not identical with, T. itoana Imai, the causal organism of snow mold disease in Japan. When the author returned to Michigan State College for the summer session of 1952, abundant material of the organism was available for the necessary experi- mental work. This consisted of observations on radial growth as discussed in the following section on Experimental Results. 15 No inoculurn was obtained from the other sites, since macros— copic observation indicated that the same organism was present, and Dr. Vaughn did not believe it necessary to work with more than one sample of the parasite. Field Study Methods The greens selected at each site were chosen in conference with the greenskeepers on the basis of the past history as the worst green on each course. Each green was divided (as indicated in Fig- ure 2) into equal plots, each approximately 1,500 square feet in area, in 1950, and approximately 1,000 square feet in area in each of the other two years, by means of marker stakes and boundary tapes. One plot was designated as the control plot and the other five were used for individual treatments. The position of each plot on a par— ticular green was randomly determined for the first year. In subse- quent years, a similar random designation of plots was made, but in no case was the same plot used for the identical treatment in more than one of the three years. The fungicides were mixed with water on the basis of ratio of weight of fungicide to volume of water as indicated in Table I. l‘ungicide strengths used, as indicated, were at the recommended 16 ———-_- ‘ ----__-_-- Blaney Park Sault Ste. Marie Houghton N (——- N (—— as ‘— 4 5 1 l 5 4 5 l 6 NJ ___) B S Cedarville r 3 """'"\ (1: 3. 1 ..... 4 l 3 6 Z 5 1951-52 ——— B 4 S C N4- ? c“ "on I 6 3 5 2 1 6 2 5 1 4 3 ‘4’ u... 1952-53 ———) \J L‘igure 2. Diagrams of experimental plots at all sites for years 1950-1953, inclusive. N = north; 1 = Acti-dione; 2 = Cadminate; 3 = Tersan; 4 = CEzC 1025; 5 '2 Calo-clor; 6 a Control plot; B = Blaney Park; C = Cedarville; S n Sault Ste. Marie. TABLE I STRENGTHS OF FUNGICIDE CONCENTRATIONS (WEIGHT OF FUNGICIDE/VOLUME OF WATER) UTILIZED IN FIELD EXPERIMENTS 4.... Fungic ide Water Area Fungicide Weight Volume Covered (grams) (gallons) (sq. ft.) Acti-dione ............. 0.8 2 1,000 Cadminate ............. 7.0 4 1,000 Tersan ............... 42.48 4 1,000 C82C 1025 ............. 42.48 4 1,000 Calo—clor ...... . . . . . .. 29.4 4 1,000 dosage of the manufacturers, as suggested by Dr. Vaughn, in the be- lief that positive indications of effectiveness would be obtained. Spraying was done in the late autumn as late as possible and just before the development of "permanent" winter snow cover. This time was selected because the damage to the grasses appar— ently occurs either during the winter under the snow cover or at the time of snow melt in the spring. The fungicides applied just before development of winter snow cover were thought to provide protection during the period that the ground was blanketed by the snow. 18 Immediately following snow melt in the spring, the greens were examined. Damage was visually estimated by the author and another unprejudiced individual. Estimates were made for each fungi- cide-sprayed plot in terms of the percentage of control (i_.e_., extert of undamaged area), in comparison to the percentage of undamaged area in the corresponding control plot. Dates of autumnal spraying and spring observations for each. site in each year are indicated in Table II. As shown in a comparison of Table II with Table III, the variation in length of time between spraying and subsequent obser- vation at the several sites is directly correlated with climatic con- ditions in each area. No personal observations were made of the experimental sites between the time of a Spring observation and the subsequent autumnal sprayings. Due to necessary duties of coaching and teach- ing during a part of these periods, and required resident attendance at summer sessions on the Michigan State College campus, such ob— servations were both impractical and impossible. However, the respective greenskeepers, as indicated in the section on Acknow- ledgments, made and reported detailed observations during the spring, summer, and autumn months of each intervening season. From their reports it was possible to assess the residual effectiveness of each autumnal s praying. 19 TABLE II SUMMARY OF DATES OF AUTUMNAL SPRAYII‘IG Allr SPRING OBSERVATION, DURING COURSE OF FIELD EXPERIMENTS v Q...— - First Year Second Year Third Year ’t S i: r S i ' 1 51 e Autumnal pr 1‘5 Autumnal pr n3 Autumnal Sprlrg , Obser- Obser- _ Obser- Spraying , Spraying , Sprayinor , fixation vation " "ration dlaIICY N-S-Soa A-14-51 O-Zé—Fl A—18-52 0-24-52 A._11..53 Parr; Cedar- O-27-51 A-lZ-SZ 0-25-52 A-18-53 ville . 5a'ultSte°I-I--10-EO A-l3-i1 N-lO—Sl A—S-SZ 0-23-57- A-2‘53 Marie Hough- ton N—4-CO A-lS-Sl a A = April; N = November; O = October. Laboratory Study {Methods The studies carried out at Michigan State College in the surn- mer of 1952 involved cultures developed from the inoculuIn collected at Sault Ste. Marie in the Spring of the same year. It was decided to determine the amount of radial growth of the fungus as grown in colonies in agar plates containing various amounts of the same fungicidal materials which had been used in the field experiments. 20 TABLE III TOTAI. SNOWFALL, AS RECORDED AT WEATHER STATION NEAREST EACH EXPERIMENTAL SITE, FOR THE YEARS 1950-1953, INCLUSIVE; INFORMATION FROM MONTHLY CIRCULARS OI‘I MICHIGAN CLIMATIC DATA (1) v fi '7 w ~v ‘ v—v v W fimvvvf Locality Snowfall in Inches per Month and Dates Oct. Nov. Dec. Jan. Feb. Mar. Apr. 1950—:1 ..... 0.5 25.1 37.9 26.6 27.0 20.7 2.5 1951— 2 ..... Trace 22 6 46.7 29.5 9.5 19.6 7.3 1952-- 3 ..... 0.; 9 5 24.0 22.9 36.5 d --d Sault Ste. Marie 1950-:1 ..... 2.0 19.6 30.6 15.1 22.2 17.5 4.5 1951-52 ..... 3.0 “.3 33.8 18.4 12.2 16.9 6.0 1952-53 ..... 2.1 14.4 12.7 32.1 23.0 16.8 9.9 Dunbar For. Exp. Sta.b 1951-52 ..... 0.3 19 33.0 19.5 10.9 19.3 5.6 1952-53 ..... 1.7 116 14.4 38.2 25.3 10.6 5.9 Calumet, Mich.C 1950-51 ..... 0.4 34.9 66.6 55.3 30.3 30.5 5.8 a Closest station to Blaney Park site. Closest station to Cedarville site. Closest station to Houghton site. Apparently no report available, since missing from official publication data. 21 The concentrations of fungicides used were 50, 100, 250, and 500 ppm., respectively. The InediuIn used was a 2. per cent malt extract agar. The fungicides, which were not autoclaved, were added to the warm, liquid medium and then serially diluted. The resulting volumes were adequate to pour eighty-four plates, furnishing four plates for each concentration for all five of the fungicides used, in— cluding the control. A separate lot of malt extract was made for each series; thus the medium for testing the concentrations and the controls was from the same original source. Each plate was seeded with a disk, approximately 5 mm. in diameter, taken from plate culture colonies seven days old. The disk was placed in the center of each plate and the plates were then stored in a refrigerator at a temperature of 10° Centigrade, as recommended by Remsberg (21). The plates were stored in dark- ness, as recommended by Vang (2.6), and radial—growth readings were recorded at 24—hour intervals for the 5 days following the first 48 hours from the initial seeding. EXPERIMENTAL RESULTS Results of Field Studies ‘I A surmnation of all data obtained during field observations is presented in detail in Table IV (Appe'fdix), and curnulatire average data are graphically represezted in I‘igures 3 to 6 inclusive. Blaney Park experimental site. Figure 3 shows the percentage of control of the five individual fungicides used at Blaney Park for the three—year period on green number three. Cadminate and Ter- san 'were used for two years only. As is readily noticed, Acti— dione gave the best control—-92 per cent. C8iC 1025 gave the next best control—-87 per cent. Calo-clor ranked third with 85 per cent control. l-‘ourth was Tersan, with 84 per cent control. Fifth was Cadminate, with 82 per cent control. The control plot at this site was 50 per cent damaged. Cedarville experime*'tal site. Figure 4 depicts the percentage of control of the five selected fungicides on green number three. At this site Calo-clor ranked first in controlling the pathogen by exhibiting control of 80 per cent. Acti—dione ranked second with 77 22 Percent of Control 23 100 90 10 i.‘ 0 v -. - as 555 Fungicides Figure 3 100 90 80 ‘1 I lfij 70 m: 50 40 Percent of Control 30 i, 20 10 O -'- ' . . . . , I“ . Bflflflfifl Fungicides Figure 4 A - Acti-dione B - Cadminate C - Tersan Figure 3. Figure 4. D - C&C 1025 E - Calo-clor F - Control Percentage of control at Blaney Park for green 3 (Cadminate and Tersan used for 2 years only). Percentage of control at Les Cheneaux Club, Cedarville, Mich-— igan, for 2 years, green 3. Percent of Control 100 90 80 ' 70 60 50 .' ' , z 40 30 20 10 0. VA'. 5:855! Fungicides Figure 5 Pe rc ent of Control 24 100 90 80 70 60 5o ‘ 1. 40 20 . 10 I i 0 ~ £335.53 Fungicides Figure 6 A - Acti-dione B - Cadminate C - Tersan Figure 5. D - C8zC 1025 E - Calo-clor F - Control Percentage of control at 500 Country Club, Sault Ste. Marie, Michigan, for 3 years, green 3 (Cadminate and Tersan used for 2 years only). Figure 6. Percentage of control for all three greens for 3 years (exception: Ce— darville was done for 2 years only). 25 per cent control. CELC 1025 was third with 72 per cent control; Ter- san was fourth as a controlling compound by a limiting control of 62 per cent. Cadminate ranked fifth. by exlfibiting 50 per cent control. The control plot as this site was damaged 78 per cent. Sault Ste. Marie experimental site. Figure 5 shows the per— centage of control of the five selected fungicides on green three at this location. Tersan. ranked first as a control by exhibiting 87 per cent control. Acti-dione and Cadminate ranked second, each {i‘g‘i 85 per cent control. Third was C&C 1025, with 82 per cent con— trol, while last in effectiveness was Calo-clor, with 77 per cent control. The control plot at t'.-.is site was damaged 50 per cent. Results at the three_locations. Figure 6 shows graphically, the average percentage of control for all five fungicides at all three sites for the three~year experimental period. Here it will be noted that Acti—dione ranks first, with 87.7 per cent control. C&C 1025 was second, with 82 per cent control. Third was Calo—clor, with 80 per cent control. Tersan was fourth, with 77 per cent control. Fifth, and last, was Cadminate, with 72 per cent control. The con- trol plots on these greens showed an average of 62 per cent damage over the entire period. Results of Laboratory Studies “he data obtained from the observations on radial growth in culture are presented in detail in Table V (Appendix) and represented graphically in Figures 7 to 10, inclusive. In these figures it will be noted that the average radial growth of the path0§_'€n in the con- trol plates was 33.75 mm.; maximum growth (in plates 1 and 3) was 37 mm., while a minimum growth. of 25 mm. was noted for plate 2. The graphs are based upon growth. attained at the conclusion. of the experiment. Figure 7 shows the average growth of Typhula sp. i..- Petri plates, each containizs-g 50 ppm. of one of each of the five fungicides (see also Table IV). As is readily noticed, Acti-dione gave the best control by keeping radial growth of the pathOgen static. Tersan ranked second best in controlling growth at this concentration by limiting average radial development to 5 mm. and maximum growth in any plate to 10 mm. Calo-clor was third, which, on an average, inhibited growth of the fungus to 21.50 mm.; followed by Cadminate, which restricted average growth to 22.75 mm.; and lastly, C&C 1025, which limited average growth to 33.75 mm. Figure 8 depicts the average growth of the organism in Petri plates, each. cor-taking, 100 ppm. of 0".€ of each of the five fungicides. Radial Growth in mm. 27 50 L 50 . 40 e 40 L- E - E 5 30L '§ 0 M U ,_. 20 .rd .3 (d m 10 r . _ O '1 - , .‘. ‘ I a I. I: Fungicides Fungicides Figure 7 Figure 8 A - Acti-dione D - C8zC 1025 B - Cadminate E - Calo-clor C - Tersan Figure 7. Figure 8. F - Control Growth of Typhula sp. in medium containing 50 ppm. of all five fungi- cides. Growth of Typhula sp. in medium containing 100 ppm. of all five fungicides. Radial Growth in mm. 2.8 50 r 50 - t r- 40 L E E .5 .q 4—) 3 o k U r—i :6 r8 «3 Dd F ungic ide s - F ungic ide s Figure 9 Figure 10 A - Acti-dione' D — C8zC 1025 - B - Cadminate E - Calo-clor C - Tersan F - Control Figure 9. Growth of Typhula sp. in medium containing 250 ppm. of all five fungicides. Figure 10. Growth of Typhula sp. in medium containing 500 ppm. of all five fungicides. 29 Here, again, Acti-dione completely inhibited growth, while Tersan ranked second, limiting average radial growth to 9.75 mm. Ranking third was Calo-clor, with an average of 18.50 mm. of growth, fol- lowed by Cadminate, with an average growth of 19.75 mm., and CELC 1025, with 40.25 mm. of growth. In Figure 9 the radial growth is shown in the medium con— taining 250 ppm. of one of each of the five fungicides. Acti—diOne, again, completely inhibited growth, while the next-ranking fungicides were Calo—clor, with an average growth of 7.25 mm., and Tersan, with an average of 10.25 mm. Cadminate gave the fourth—best de- gree of control, limiting growth to an average of 13.75 mm., while C&C 1025 ranked a poor fifth, with radial growth controlled at 44.50 mm. In the fourth concentration of fungicides, plates with 500 ppm. of each of the five fungicides were prepared. Acti-dione and Calo- clor both completely inhibited growth. Following these two was Ter— san, which limited radial growth to 8.50 mm. Cadminate limited growth to an average of 9.25 mm., and C&C 1025 was once again a poor fifth, with growth at 30.00 mm. Figure 10 depicts the results at this 500 ppm. concentration. 30 The probably significance of these observed results will be discussed, tOgether with the results obtained from the field studies, in the section of this paper whicxz immediately follows. DISCUSSION The number 3 green at Blaney Park was selected because of its previous history as the green most severely attacked by Snow mold on this course. It was approximately 6,000 square feet in size and was elevated at the south perimeter approximately two to three feet above the opposite side of the green. In addition, it had a slight depression bisecting it about midway from either side. In the average winter this green is covered with two feet or more of snow. These features all indicate that the locality should be favor- able for snow mold attack, and it was rather evident this had, in fact, been severely attacked so consistently because of this location. In the first year, Acti-dione, Calo-clor, and C&C 1025 were used. The following two years, Cadminate and Tersan were added for the remainder of the eXperiment. The elevated portion of the green seemed most consistently free from attack, whereas the depressed area seemed to be most frequently attacked. It was on this latter area that the melting ice and snow had lingered the longest. The fungicides used were rotated over these areas from year to year so that each was given the Opportunity to cover a portion of these critical areas. As is noted in Figure 3, Acti-dione 31 32 gave very good control on this green, with approximately 90 per cent effectiveness, while C&C 1025 ranked second, with 86 per cent control and was closely followed by Calo-clor and Tersan, with con- trols of 85 per cent and 84 per cent, reSpcctively. Fifth was Cadmi- nate, with 82 per cent control. By contrast, the unsprayed control area for this green exhibited 50 per cent infection. Figure 11 shows the depressed area of Blaney Park greei number 3 with typical 'mottling a.:d coalescing Spots of infection. Figures 12 and 13 are close-up Views of the same area, showing more distinctly the mottling pattern of infection and typical coalescing of the mycelium. This same pattern of attack will be seen in subse- quent photographs taken at the 800 Country Club at Sault Ste. Marie, Michigan, and the Les Cheneaux Club at Cedarville, Michigan Figures 14 to 19, inclusive). , The mottled areas shown are principally the white, wool-like mycelium which was first observed soon after the snow had disap- peared from the green. If now drying winds are obtained soon after, the plants begin to rot and die, and mat down. Some of these brown, dark matted areas are shown in Figure 13. As previously mentioned, the Les Cheneaux Club at Cedarville, Michigan, was substituted for the Portage Lake Club at Houghton, 33 PHOTOGRAPHS OF GREEN NUMBER 3 AT BLANEY PARK GOT’JF COURSE, BLANEY PARK, MICHIGAN Figure 11. Blaney Park green 3, showing depressed area with typical mottling and coalescing of infection Spots. Figure 12. .Blaney Park green 3, close-up view showing large infection area. Figure 13. Blaney Park green 3, extreme close—up view of area attacked by Typhula sp. 35 Michigan, after the first year's tests. Hey-.ce, o:-ly two years' re— sults of testing for this course are gives. in. Figure 4. However, this was a most interesting green to test experi— mentally, since it was flanked on the eastern side by a high snow fence. Consequently, he green was under a snow cover approxi— mately 6 feet deep from early November until late April. It was also surrou:_ided on three sides by heavy woods, which allowed poor air drainage over the green. These factors were co.;sidered by the author when. he selected the mmber three green for this field testing prOgram. Due to the abundance of snow on this green, and its slowness in melting clear, the Spring visits for recording the results were made later than the Spring visits to the 500 Country Club and Blaney Park. However, it is felt that the results recorded are sufficiently significant to warrant inclusion here. At this later date, some small portions of this green were still covered with snow. On the whole, however, the major portions of each area were clear, and the proportionate areas recorded were typical control for the entire green. Calo—clor rated number one as the controlling fungicide on this green, giving 80 per cent control. Acti-dione was second with 36 78 per cert control, followed by C8,:C 1025, with 73 per cent control. Tersan exhibited 62 per cent control, wnile Cadminate was 50 per cent effective. This green was quite hard hit by Show mold over the two-year period tested, averaging 78 per cent infection on tne control plot. Figure 15 is a photograph showing a close-up of the white, wool-like mycelium found on this green April 4, 1953. This flossy mycelium was found extensively on this green at this date. The area estimated to be covered was 80 per cent of the control area. Figure 14 shows typical mottling and coalescing of the af— fected areas. The light Spots are the matted, dead turf. .Figure 16 is an extreme close—up view of a portion of the control area, show— ing, in greater detail, the irregular, mottled, blotched pattern. The infected areas seem to grow outwardly from the certer, and under favorable temperature and humidity conditions continue to enlarge and unite with each other. It was here noted that, at a later date, these same infection spots showed evidence of beginning recovery in the very center. New blades of grass were in evidence, although very few in number. It was also noted that the new growth appeared much darker in color than the surrounding turf. The af- fected spots later, and after apparent recovery, also showed this 37 PHOTOGRAPHS OF GREEN NUMBER 3 AT LES CHENEAUX CLUB, CEDARVILuE, MICHIGAN Figure 14. Les Cheneaux Club, Cedarville, Michigan, green 3; ClOSC—‘...p s rowi 1g t'y;ical coalescig of t...e ifectio - areas. Figure 15. _'-'_-.es Cheneaux Club, Cedarville, Michigan, green 3; close-up showing white, flossy, wool—like mycelium of Typ7~_1-.la sp. Figure 16. Les Cheneaux Club, Cedarville, Michigan, green 3; close-up of control area showing clearly the in- fection pattern of TprmIa sp. l‘. ‘» ( I of: ~ ‘- - .' l' _‘ . p": \'- .;I > ‘ 39 characteristic smoky blue-green color. TILiS covdition also was in evidence at the other two courses studied. This condition gives the green an undesirable appearance, in that the turf coloring is not uniform. The number 3 green at the 500 Country Club in Sault Ste. Marie was selected for teSting on the basis of its past history for infection... It was readily accessible in the spring for early observa- tions, so "233'; a very close check was kept on the progress of snow mold develogment from the time tne snow first began to melt un- til many weeks after its fiial disappearance. This green was com- paratively high, windswept, and covered by no more than one foot of snow most of the winter. It usually did not become covered until late in November, and was relatively free from snow-cover early in the spring. These, in addition to its high incidence of attack by snow mold in previous years, were the determining factors in the selection of this green for study.“ As shown in Figure 5, Tersan gave the best control of the five fungicides used on this green; control was 88 per cent. Fol- lowing closely are Cadminate and Acti-dione, which gave 85 per cent control each. C&C 1025 ranked third, with a control of 83 per cent, and Calo-clor was last, with 77 per cent control efficiency. For 40 the period studied, the control plot of this green was 50 per cert affected on the average. Calo—clor has been used by the greenskeeper at the 500 Country Club for the past few years, late in the autumn, for snow mold control. However, he applied it in a dry state and without scientific preparation insofar as method of application and even— coverage were concerned. Furthermore, after application of Calo— clor, the greens were not watered dovm., as is the usual and recom- mended procedure for the mercury compounds. It might be added that the over-all appearance of the greens at this country club was much better than that found at the other clubs under observation. Even so, all of the greens at this course showed evidence of having been attacked by snow mold at various times. Hence, it is doubtful in the author's mind just how valuable the autumnal application of dry Calo—clor on these greens has been. Figure 17 is a photOgraph showing the very early stages of infection on the untreated green number 8 at the 500 Country Club. Large irregular blotches can be detected 0.1 the surface of the turf in this view. These are the white and brownish-white mycelial mats formed at the areas of infection. Figure 18 is a close-up view of one of these mycelial mats; this particular view is of the control 41 PHOTOGRAPHS OF GREENS 8 ANI.) 3 AT 500 COUNTRY Figure 18. figure 19. CHUB, SAUL/T STE. MARIE, MICHIGAN 800 Country Club, Sault Ste. Marie, Michigan green 8; early stages of infection of T‘~Z';;-'?11-Lla Sp; this green. was t'ntreated. 800 Country Club, Sault Ste. Marie, Michigan, green 3; close—up of mycelium mat or. the control area, rather gummy in appearance at this stage. Sbo Country Clu‘, Sault Ste. Marie, Michiga;., green 3; control area showing large dried blotches of infectious material 0‘: surface of tree .. t \ ." d ' ‘ ‘ v - . c Q“. .J E . ' c ",o\ . ' . 3‘s 0" reg. s .\ O . . . 43 area of green 3, the green under Observation. One will readily no- tice the flossy—white and somewhat gummy appearance of this spot of infectious material. This is typical of the organism in its earlier stages. Scrapings were taken for laboratory culture from this area in the spring of 1952. It was from this culture t-.at the laboratory correlation work was performed. Figure 19 is another close-up view showing the irregular blotches of mycelium in early stages on. green 3. These measured approximately 4 to 6 inches across at the time they were photo- graphed, and later coalesced to such a degree that they covered many square feet of the control area of the green. At this stage the green was decidedly unsightly, and as the infection increased in quantity and intensity, the turf became less and less pleasing in its appearance. It has been noted at this location that the turf nas re- covered very slowly each year from the damage incurred by this pathOgen. However, it required most of the summer mo..1ths for such recovery, and all the while the greens have not presented eye- appeal to the golfer. Green number 3, which has been under testing for these three years, has brought favorable comment from numerous individuals in regard to its appearance and state of lzealthfulness. Many of the persons who made these com'nents were unaware of the testing: program and the author's work on same. They were purely unsolicited remarks of a complimentary nature concerning the aforementioned green. The graph in Figure 6 sum'narized results for all three areas under observation for the entire three—year period the pro- gram was carried on. The detailed data which form the basis for this figure are given in Table IV. In the laboratory correlation work, it is of interest to note that the radial growth of the pathOgen on the plates of C&C 1025 exceeded the growth on tne control plates (Figures 8, 9). It is therefore interpreted that, at the concentrations of 100 ppm. and 250 ppm., C&C 1025 apparently was stimulating to the organism. Moreover, at 50 ppm., average radial growth .was exactly equiva- lent to that of the control, while at 500 ppm., slight inhibition was shown. It is difficult to explain the effectiveness of C&C 1025 in the field when, in the laboratory, at least in certain concentrations, it appeared to stimulate growth of the pathOgen. The mode of ap- plication, time of application, stage of deve10pment of the pathOgen, or some unknown factors such as the effects of competing soil or- ganisms, must have been decisive in bringing about its effectiveness in the field. Except for this one exception, there is comparatively 45 good correlation. betweea the laboratory a-:=_d field resu ts. Acti-dio:.e, then, ranked first in the field and first in the laboratory. The other three compounds of Calo-clor, Tersan, and Cadminate rated 2—2, 3-3, 4—4, reSpectively. The five fungicides used were selected for a representative sampling of the many types of available fungicides. Since this was the first time an experiment of this type was known to have been attempted in the State of Michigan, it was felt that representatives of various classes or types of fungicidal agents should be tested. Represented in t'.:-is sampling are an antibiotic (Cycloheximide = Acti-dione), and organic cadmium (Cadminate), and organic sulphur (Tersan), an. ir.orga‘.ic mercury compouid (Calo—clor), and CLLC 1025, which contains Ci§?.1’0mi1un-a_u.d mercury as active i;:gredie;t.ts. No consideration. was given to the cost or ecoromy of any of the fungi— cides used in these trials, since the major endeavor was to deter- mine the most efficient fungicide for inhibition or control. Based up0n the aforementioned facts, it is evident that fungi- cides differ in efficiency from green to green and from year to year. factors influencing the results may be position and t0pography of the green, environment, and geographical location. All of these, plus local soil factors, could easily influence the nunnbers of 46 soil-borne organisms present at any one time in any giver". area. On the other land, some consistency was noted, since Calo-clor was rated first at Cedarville green :i-rmher 3 for two consecutive years. This particular green, with its extremely heavy Snow cover, COT'ld not be analyzed for disease incidence until later than the other sites. There is a possibility that Calo—clor has better residual action than the other four fungicides, and was thus able to he effective over this longer period of time. Some challengiz‘ig questions brought out in this particular in- vestigation, and which may be of interest for future experimentation, concern the following: (1) tent grass varieties; (2) time of spray application; (3) specific action of the fungicides; (4) residual actio.-. of the fungicides. It is not known what would occur if the same fungicide were applied to the same plot for a given number» of years. Cumulative residual action may affect to a large‘ degree the control attained in subsequent years. There is also the possiaility that one or more of the fungicides tested could be detrimental to the natural soil-borne antagonists which may aid in disease control. This could be brought out by a testing method such as that just described. It also would be interesting to test all available strains of bent grass for varietal resistance; this is known to occur in relation 47 to the other diseases of fine turf. Work of this type would be dore by artificial inoculation, not only wit}- 232591;": spp., but also with. -‘usariurn spp., wlzici- are also known to cause slow mold. Still anotlzer approach is to test for varietally resistant strains among the pathogens. An.ot.':-er aspect that could be tested would be applications of various fungicides to tie plots atvarying times, beg—inning several weeks before "permanent" snowfall is expected, or at intervals during the gradual establishment of the snow cover. There is the possibility that the snow mold organisms may begin to grow actively witl the advent of cold weather; thus the mycelium would be much more susceptible to fungicidal action than would dormant sclerotia. Precise-timing may allow considerable eradication without reducingr the amount of fungicide left available for residual preventative action in the spring. In contrast, fungicidal applications to melting snow could be expected to be efficient if rapidly growing mycelium was present at such a time. A limiting factor in spring applications would be the depth of Snow cover resulting in possible excessive di— lutions of the fungicide. Since it is not knOWn whether the fungus was completely killed, or only severely inhibited, in the Petri plates used in the 4?.“ laboratory experiments, a testirg prOgram could be set up to determine the extent and rapidity of such fur--gicidal action. This would be ac- complished by transplanting; disks of seemingly inLiLited mycelium to pure nutrient agar. If t1..is were set Lp as a time study, tire exact number of hours for complete killing to take place coxld be dete rmired . SUMMARY The effects of "winter—kill" oz- bent grass golf greens on- many golf courses in the upper peninsula of Michigan-were ob- served during the summer and early autumn of 1950. This con- dition was suspected to be pathogenic in origin. Turee representative sites were selected for study, and the worst green, on the basis of past Listory, was cliosen at each. of the three golf courses. These courses were located in the vi— cinity of Blaney Park, Sault Ste. Marie, and Houghton. Because of extreme climatic COnditions, a course near Cedarville was substi— tuted for the one at Houghton after the first year of experimental work. Three, and later five, commercial f1=ngiicides were selected for study of experimental control of the "winter-kill," which was determined to be equivalent to Snow Mold disease in which one path— ogen is a species of Typhula. The principal fungicide under con- sideration was Acti-dione, on whicl'; considerable experimentation was underway; the other fungicides were chosen for comparative studies of relative effectiveness of control of the disease. These other fungicides were Cadminate, Tersan, C&C 1025, and Calo-clor. 49 50 TV: selected greens were divided into 6 equal plots each of approxi- mately 1,000 square feet area; ore of these was assigned as a cor— trol plot and each of tie other plots was sprayed witl‘: a double— strength solution of a particrlar frrngicide. Spraying was done in the late autumn just prior to development of "permanent" winter snow cover. Observations on effectivex'xess of control were made early in the following spring at snow—melt time; these Observations were in t1.-e form of perce.,:.tage of control (_i_._e_., percentage of un~ infected or undamaged green area), in comparison to that of the control plot at each site. Spraying and subsequent observations were made over a three—year period ir-cli...ding t}..e seasons 1950—1951, 1951-1952, and 1952-1953. Laboratory studies were made during the summer of 1952. with cultures developed from inoculurn from the Sault Ste. Marie site. These studies consisted of five-day observations of radial growth on seeded plates with the observations beginning 48 hours after seeding. The plates were prepared from 2 per cent malt ex— tract agar to which the individual fungicides were added; four serial dilutions of 50, 100, 250, and 500 ppm. were used in this phase of the study. Radial growth was determined in millimeters of mycelial expansion from the focal center of seedi:::;;. CON CLUSION S 1. The relative ranking of the five fungicides, in order of decreasing effectiveness of control in the field experiments is as follows: (1) Acti-dione; (2) C&C 1025; (3) Calo-clor; (4) Tersa-w; (5) Cadminate. 2.. In the laboratory experiments the ranking, in order of decreasing effectiveness is: (l) Acti-dione; (2.) Calosclor; (3) Ter— san; (4) Cadminate; (5) C&C 1025. 3. In“ the laboratory experiments the C&C 1025 appeared to act as a stimulant to growth, rather than a retarda:,.t, at concen- trations of 100 and 250 ppm. At a concentration of 500 ppm. there was inhibition of fungal growth, but at a concentration of 50 ppm. the growth was equal to that of the control. 4. On the basis of the experimental work the recommendatiors for control of snow mold disease, with respect to the five fungicides, are as follows: (a) Acti-dione is the most effective of the five, and, if available, should be used in preference to the others; (b) All five of the fungicides, since they gave 74 per cent or better control of the disease, can. be effectively used i‘J. protectizxj 51 ((1) beat grass golf greens in... the area studies; further experimental work, utilizing time of fungicide application and increased dosages (beyond the double-stremth used in these experiments) should be carried out; -.‘urtl':er experimental work should be undertaken to determine the nature of infection. and the longevity of tie organism in soil surface. lO. LITERATURE CITED Anonymous. Climatological data. Michigan. U. S. Dept. Com—- merce, Weath. Bur. 55(10—12); 56(1-4, lO—lZ); 57(1-4, lO-—12); 523(1-4). No pagination, USDA Bur. Comm., Kansas City, M0. 1950-1953. Blodgett, E. C. Winter injury of fall seeded wheat in Idaho. Rev. Appl. Mycol. 25: 551—552. 1946. Bowen, C. C. A comparative study of the effects of several antimitotics. Unpublished Ph.D. thesis. iv, 99 pp. Mich. State Coll. Dept. Botany and P1. Path., East Lansing, Michigan. 1953. Brundze, K. Calonectria graminicola (rye snow fungus). Rev. Appl. Mycol. 25: 63-64. 1946. Davis, 8. H., Engel, R. E., and Silber, G. Control of brown patch of turf in New Jersey. (Abstr.) Phytopath. 41: 657. 1950. Davis, W. H. Snow mold and brown patch caused by Sclerotium rhizodeg. Phytopath. 23: 8. 1933. Ekstrand, H. Overwintering of autumnesown cereals and meadow grasses. Rev. Appl. Mycol. 18: 298-299. 1939. .. Some economically important diseases of autumn—sown grains and grasses. Rev. Appl. Mycol. 18: 23—24. 1939. Fernald, M. L. Gramineae (grass family). 1.9.3 Gray's manual of botany. ed. 8. pp. 94-236. American Book Company, New York, New York. 1950. Gleason, H. A. Gramineae, the grass family. E: The new Erit— ton and Brown illustrated flora of the northeastern United States and adjacent Canada. L: 96-246. New York Botanical Gar- den, New York, New York. 1952. 53 11. 12. 13. 14. 16. 1'7. 18. 19. 20. 21. 22. 54 Gottlieb, D., Hassan, H. H., and Linn, M. 13. Acti-dione as a plant protectant. (Abstr.) Phytopath. 40: 21%". 1950. Hawthorne, Mary E. The cytological effects of the antibiotic Acti—dione. Unpublished Ph.D. thesis. vi, 184 pp. Mich. State Coll. Dept. Bot. and P1. Path., East Lansing, Michigan. 1951. Hawthorne, Mary E., and Wilson, G. B. The cytological effects of the antibiotic Acti-dione. Cytologia 17:71-85. 1952. Hitchcock, A. S., and Chase, Agnes. Manual of the grasses of the United States. USDA Misc. Publ. 200; ed. 2, rev. pp. 1051. Washington, D. C.; U. S. Government Printing Office. 1951. Hclton, C. S. Observations and experiments on snow mold of winter wheat in Washington State. U. S. Dept. Agr. Plant Dis. Rptr. 37: 354-358. 1953. Howard, F. L. 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APPENDIX The two tables which follow co itain all of the "raw" measurement and observation-estimate data obtained during the experimental work on this problem. These data are here i;-c1uded for reference in future work, either by the author or some other person, on this problem. 56 TAB? .,E IV SUMMATIOI‘I OF ALL DATA OBTAINED BY FIELD OBSERVATIONS ON THE EFFECT OF FIVE FUNGICIDES IN CONTROL OF SNOW MOLD DISEASE AT FOUR LOCALITIES IN MICHIGAN (see text for exact locations of experimental sites) ‘9 Vfi P . Per Cent of Control (undamaged area) Ct Cf . . . . J Undam— Localities, by Fungicides aged Dates, and Ar a in Averages Acti- Cad— ,, c-zzc Calo- e , lersan , _ Control dione minate 102:;- clor Plots Blaney Park a a 1950 ...... 93.0 -- —- 90.0 66 7 1951 ...... 93.0 99.0 99.0 95.0 85.0 85 0 1952 ...... 95.0 65.0 70.0 75.0 80.0 0.0 3-year avg. . . . 88.3 82.0b 84.5b 86.7 85 o 50 7 Cedarville 19:1 ...... 80.0 60.0 60.0 75.0 75.0 35 0 1952 ...... 75.0 40.0 50 0 70.0 85 0 10 0 2—year avg. . . . 77.5b 50.0b 62 5b 72 5b 80.0b 22 5b Sault Ste. Marie a a 1950 ...... 60 0 -— —- 80.0 80 0 25 O 1951 ...... 90 0 90.0 95.0 95 0 6S 0 50 0 1952 ...... 95 0 80.0 80.0 75 0 85.0 25.0 3-year avg. . . . 81.7 85.0b 87.5b 83 3 76.7 33 3 Houghton 1950d. . . . . . 95.0C -—a "3 85.0C 85.00 65.0C Fungicide- avg. . 85.7 74.0b 78.0b 82.3 81.0 39.7 a Not used (see text). 2 years only. 1 year only. (1 "Average . ' ' TABLE V SUMIVIATION OF ALL DATA OBTAINED BY LABORATORY OBSERVATIONS ON THE II‘JE-JBITION OF RADIAL GROWTH OF THE SHOW MOLD PATHOGEN BY TEIE FIVE FUIIO‘ICIDES fl V v iW—v Fungicides Used AA...— Concentration Time Ac ti—dione Cadminate 132 3412 34 50 pan 48 hours 0 0 0 0 0 0 0 0 72 hours 0 0 0 0 14 12 15 15 96 hours 0 O 0 0 18 19 20 20 120 hours 0 0 O 0 19 20 25 24 144 hours _0 0 0 _9_ 21 22 28 25 4—plate average 9__(_)_0_ 22.75 100 pan 48 hours 0 0 0 O 0 0 0 0 72 hours 0 0 0 0 14 13 14 14 96 hours 0 0 0 0 18 18 18 16 120 hours 0 0 0 0 19 19 19 17 144 hours ,0 0 9 0 21 19 20 19 4-p1ate ave rage 9_._0_Q 19.7.r 250 pan 48 hours 0 0 0 O 0 0 0 0 72 hours 0 0 0 0 10 11 10 9 96 hours 0 0 0 0 11 14 11 10 120 hours 0 0 0 O 14 15 13 11 144 hours _0 0 0 0 16 5 13 11 4-p1ate average 0_09_ 13.75 500 pan 48 hours 0 0 0 0 0 O 0 0 72 hours 0 0 0 0 5 8 5 5 96 hours 0 0 0 0 8 10 7 7 120 hours 0 O 0 0 9 10 7 7 144 hours ,0 0 0 0 10 11 8 8 4-plate average 0 00 _9___._2_5 . t l v—v V—v v—vvv 7* V v r w—v v f Numbers 1, 2, 3, and 4 are plate numbers. TABLE '." (Continue (1) Fungicides Used Control Tersan C&C 1025 Calo—clor 0 0 o 0 0 0 0 0 0 0 0 0 0 o 0 0 0 o 0 20 19 18 18 12 14 17 14 20 15 21 0 0 7 7 28 28 29 29 16 18 21 17 28 20 30 0 0 9 9 32 29 32 32 17 22 24 17 32 22 35 0 0 10 10 38 29 33 3: 18 23 26 19 37 25 37 ;:99_ 33.75 21 50 33xu. 0 0 0 o 0 o 0 o 0 0 o 0 o 0 0 5 19 19 18 24 12 12 14 10 0 7 7 7 25 27 28 30 17 14 18 14 7 10 9 7 33 33 33 38 19 17 20 15 ,0 12 10 7 37 40 39 45 20 17 21 16 9.75 40.25 18.50 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 18 19 18 17 0 0 0 o 3 4 4 4 2 7 2 7 2 6 2 3 0 6 6 5 6 7 9 9 35 36 36 32 0 9 8 8 9 10 12 43 41 44 38 0 10 10 9 10.2; 44.50 3;;5. 0 0 0 0 0 0 0 - 0 0 0 o 0 0 o 0 15 15 13 14 0 0 0 0 0 0 0 0 3 22 18 20 0 0 0 0 6 7 10 6 30 28 22 25 0 0 0 0 6 11 11 6 35 31 26 28 0 0 0 0 8.50 30 00 9,99_ ,\.,1- - __.._._. ::_*:a.;;aa_..,’aa.a £> . S x' :7: ?> 2.}, <:‘ \ ..\ II. ‘t‘ .1 ‘ 3 Cu R A P . B t 1. IV 7| .5 R V N U E Tl A TI 5 1 r-HGAN M f