> 1 THE UNIVERSITY OF ILLINOIS LIBRARY 630.7 I16b cop-Z A6RICULTURAL ING I UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN NO. 242 FLAG SMUT OF WHEAT, WITH SPECIAL REFERENCE TO VARIETAL RESISTANCE IN COOPERATION WITH OFFICE OF CEREAL INVESTIGATIONS BUREAU OF PLANT INDUSTRY, U. S. DEPARTMENT OF AGRICULTURE BY W. H. TISDALE, G. H. DUNGAN, AND C. E. LEIGHTY URBANA, ILLINOIS, APRIL, 1923 ACKNOWLEDGMENT The writers wish to acknowledge their indebtedness to the following persons: Dr. George M. Reed, who super- vised the work for the Office of Cereal Investigations, U. S. Department of Agriculture, during its earlier stages ; Drs. W. L. Burlison and H. B. Humphrey, for advice and helpful criticisms of the manuscript; Professor J. C. Hackleman, for advice regarding varieties; the Board of Education of the Granite City Community High School, Madison county, Illinois, who kindly furnished land for the experiment plats; Mr. Louis Soechtig, who prepared the land for planting and who has cooperated cheerfully by increasing certain varieties that show resistance to flag smut; and Miss M. A. Griffiths and Mr. F. S. Wolpert, for assistance in the work as it was in progress. CONTENTS OP BULLETIN No. 242 PAGE SUMMARY 510 INTRODUCTION 511 HISTORY AND PURPOSE OF INVESTIGATIONS .512 OCCURRENCE OF FLAG SMUT 512 LOSSES DUE TO FLAG SMUT 513 SYMPTOMS 514 THE CAUSAL FUNGUS ( Urocystis tritici Kcke.) 515 DISSEMINATION 516 CONTROL MEASURES 519 Experiments in Control by Seed Treatment 519 Control by Crop Rotation 521 Experiments in Control by Date of Seeding 522 VARIETAL RESISTANCE 523 Experimental Work to Determine Varieties Completely Resistant 524 Varieties Apparently Highly Resistant 526 Wheat Varieties Generally Grown in the Flag Smut Area 530 INDEX OF ALL WHEAT VARIETIES TESTED, SHOWING RESIST- ANCE AND SUSCEPTIBILITY TO FLAG SMUT 531 CONCLUSIONS 537 LITERATURE CITED . ..538 SUMMARY Flag smut has caused severe damage to wheat in Australia and local damage in Japan and South Africa. It is known to occur in India and China but the extent of the loss caused is not known. The disease was found first in the United States in 1919, near Granite City, Madison county, Illinois, and is thought to have been introduced from Australia. It has now spread over an area in Illinois about fifty miles long and five to fifteen miles wide. An infested area in Missouri adjacent to that in Illinois includes only four fields. The disease is spreading at a rather steady rate. As yet severe losses by the disease have not been extensive in the infested area in this country. However, rare cases of an infection up to 30 percent in parts of fields indicates that the disease may cause severe loss if no precautions are taken to hold it in check. In Australia the effects are said to be cumulative. One of the chief sources of infection is the spores that cling to the seed, which contaminate threshing machines, wagon beds, grain bins, etc. A second source is the spores in the soil, which may come from infested straw and manure, or be carried by wind or streams, or by animals or vehicles passing thru the in- fested area. It is not known how long the spores will live in the soil, but it is known that some of them survive the winter months. Because of the fact that the spores easily survive the summer and are present to infect fall-sown wheat, it is especially important that fields growing smutty wheat be sown to other crops the following year. Any other crop may be used, as flag smut affects only wheat. In experiments in which seed was first smutted and then treated with fungi- cides, it was found that the disease was practically controlled in the plots where copper sulfate and lime, and where copper carbonate had been used. The treat- ments, however, failed to control the disease when the seed was sown in furrows in which spores of flag smut had been previously dusted. In a three-year experiment to determine the effect of the time of sowing on the development of flag smut, it was found that the wheat sown after the first of November or in the spring was much less subject to flag smut than the wheat sown in the early fall. This was doubtless owing to the fact that tempera- tures at that time are too low for spore germination. Sowings made after the middle of November were smut free, but the yields were very low. In the course of three years' experiments nearly two hundred varieties or strains of wheat were tested for susceptibility to flag smut. The seed was thoroly smutted with the spores of the fungus and sown in the infested area. Some fourteen varieties or strains were found to be immune and forty-one others were highly resistant. Some of these are adapted to the conditions ex- isting in the infested area, while others are not. Several of the adapted varieties are being increased for wider sowing and for further testing in this locality. Immune varieties that are adapted to the infested area include Beechwood, Ful caster (Marvelous and Stoner), Imperial Amber, Bed May (Early Harvest), Bed Bock, and Shepherd. Of the varieties commonly grown in the infested area, Harvest Queen (Bed Cross or Salzer's Prizetaker) was found to be the most susceptible varietj'. Flint (May), Gipsy (Niagara), Bed Wave, Jones Fife, and Fultz also showed a high percentage of infection. FLAG SMUT OF WHEAT, WITH SPECIAL REFERENCE TO VARIETAL RESISTANCE BY W. H. TISDALE, G. H. DUNCAN, AND C. E. LEIGHTY" INTRODUCTION The discovery of flag smut (Urocystis tritici Kcke.) in May, 1919, in some of the wheat fields of Madison county, Illinois, added another pest to the already rather long list of troubles known to affect wheat in the United States. Knowing the importance of flag smut as a destruc- tive parasitic fungus in Australia, American plant pathologists and agronomists, on learning of its occurrence in this country, at once became interested in what might be its capacity for crop destruction under changed conditions of environment, in its epidemiology, and in methods for its control. Fortunately, flag smut thus far has been found in but a limited area in southwestern Illinois and on four farms in St. Louis county, Missouri. To be sure, it has never, even under the most favorable conditions, proved so destructive as bunt or stinking smut of wheat, but its effects are none the less worthy of serious consideration. Losses amounting to as much as 10 to 20 percent are not uncommon ; and these losses, added to those caused by rusts and by other smuts, by scab, and other diseases peculiar to the wheat crop, form no incon- siderable part in an aggregate reduction of yield that on the whole is enormous. The research herein reported has contributed materially to the existing knowledge of the habits and life history of the flag smut organism, the etiology of the disease, and methods for its con- trol. Quite the most important result of these studies has been the discovery of a number of important varieties of wheat that are either immune from, or highly resistant to, flag smut. These varieties offer the most promising means of controlling this destructive disease. W. H. Tisdale, Pathologist in Charge of Cereal Smut Investigations, Office of Cereal Investigations, Bureau of Plant Industry, U. S. Department of Agri- culture ; G. H. Dungan, Associate in Crop Production, University of Illinois Agri- cultural Experiment Station; C. E. Leighty, Agronomist in Charge of Eastern Wheat Investigations, Bureau of Plant Industry, U. S. Department of Agriculture. 511 512 BULLETIN No. 242 [April, HISTORY AND PURPOSE OF INVESTIGATIONS Immediately after the discovery of flag smut of wheat in Madison county, Illinois, in 1919, arrangements were made for a cooperative investigation of the disease by the Office of Cereal Investigations, Bureau of Plant Industry, U. S. Department of Agriculture, and the University of Illinois Agricultural Experiment Station. The pur- pose of this bulletin is to discuss the results of these investigations: namely, the history of the occurrence of flag smut, the losses caused, a description of the disease and the causal organism, the dissemination of the smut fungus, and finally, but most important, the results obtained thru experiments conducted in the infested area, near Granite City, Illinois, for the purpose of controlling the disease. It is very desirable that the wheat farmers of the United States be informed as to the nature of flag smut and the available means of holding it in check. OCCURRENCE OF FLAG SMUT Flag smut of wheat is now known to occur in a number of coun- tries thruout the world. The first reports of its occurrence came from Australia, where it was reported by the South Australian Commission on Diseases of Cereals in 1868. 16 Since that time it has been found to be widely distributed in South Australia and to occur in Northern Victoria, New South Wales, and Queensland. 16 It was found by Hori 11 in Japan in 1895, and by Sydow and Butler 23 in India in 1906. In 1920 Putterill 21 reported the occurrence of the disease in South Africa, where it is commonly known as "Tulp brand" or "Stoel brand." He thinks that it has been present in South Africa for a number of years.* Flag smut was first found in the United States in Madison county, Illinois, on May 5, 1919. 12 In that year it was found in a number of fields in the vicinity of Granite City, where it was first noted. 22 - 24 In 1920, in an extensive survey made by the Office of Plant-Disease Survey, Bureau of Plant Industry, U. S. Department of Agriculture, in cooperation with the Illinois State Department of Agriculture, flag smut was found in 111 fields in the county in an area comprizing about 47 square miles. 22 ' 24 In 1921 the disease was^ found to be spread over an area of 65 square miles in Madison county and 15 square miles in St. Clair county, Illinois. 8 The survey of 1922 8 showed flag smut to be present in two additional counties in Illinois : viz., Jersey, north of Madison county, and Monroe, south of St. Clair county, and also in St. Louis county, Missouri. The infested area in "This and similar reference numbers refer to "Literature Cited," page 538. 'Since the preparation of this manuscript the authors have had access to a translation of a Japanese paper written by Miyake, in 1912, in which he notes the occurrence of flag smut in China. 38 19183] FLAG SMUT OP WHEAT 513 Illinois is about fifty miles long and five to fifteen miles wide. The infested area in Missouri is adjacent to that in Illinois and includes only four fields. The enlargement of the area from year to year probably has not been due entirely to spread of the disease but to wider and more thoro search. The survey has been limited because of lack of funds and men available for the work. The indications are that some of the recently discovered infestations have existed for a number of years. The records do indicate, however, that the disease is spreading at a rather steady rate. According to Brittlebank, 2 it is probable that flag smut was intro- duced into this country from Australia. He states that during the year 1918, 51/2 million bushels of wheat were exported to the United States from Australia. This wheat was supposed to be used for milling purposes only, but some of the contaminated by-products such as bran, or even the grain itself, might have escaped into the fields thru some of the numerous possible agencies. The fact that flag smut was found the next season following the importation of Australian wheat seems to furnish considerable evidence for Brittlebank 's theory that the disease was introduced into this country from Australia. LOSSES DUE TO FLAG SMUT It is possible for the damage caused by flag smut to be heavier than might be suspected from looking at the mature wheat crop. Diseased plants generally are much dwarfed and the smutty plants seldom produce heads, but die before the wheat is ripe. Thus the diseased plants may easily be overlooked and the thin stand and light harvest not be attributed to the smut. According to Brittlebank, 1 the disease may cause unsuspected damage thruout the growing season. In 1905 Me Alpine 15 stated that in some seasons in Australia severe losses had been caused by the disease. In 1910 the same writer 16 made the following statement : "In Victoria as much as half the crop may be lost thru it and in New South Wales, Cobb has shown it 'to be equally bad. Where wheat is grown year after year and no precautions taken against this disease, the effects are cumulative. This will account for the widespread and injurious effects of this disease in many wheat growing districts." Later reports made by Australian writers seem to bear out the state- ments made by McAlpine that the effects are cumulative. Brittle- bank, 1 in 1920, says, "Considering that rust epidemics are few and far between, while flag smut is annually taking toll of from 5 percent to nearly 70 percent, the total loss caused by rust sinks into insignifi- cance when compared with that resulting from flag smut." Rust is regarded by some as being the most destructive disease of wheat in Australia. 1 514 BULLETIN No. 242 [April, Hori 11 reports considerable local damage to the wheat crop from flag smut in Japan as early as 1895. No recent reports have been received from that country. The disease is known to occur in India 23 but there are no available reports of the losses caused by it. Putterill 21 makes the following statement regarding the losses due to flag smut in South Africa: "During the last two or three years, wheat farmers at Zeerust, in the Marico District of the Transvaal, have been con- siderably alarmed at the loss in their wheat crops sustained thru the ravages of this smut. While the total loss up to now may not be considered very great in that district, yet in some wheat fields lately visited almost half the crop was found to be affected." Flag smut has not yet caused any very serious losses in the United States. In most fields, infections have been scattered and difficult to find. In some cases, however, fields have been found showing as many as 5 percent of the plants infected. In extremely rare cases, from 5 to 30 percent of infected plants in parts of fields has been reported, and in one field of thirty-five acres an average infection of 17 percent was found. 8 The fact that seed treatment and other measures, such as the use of resistant varieties, have been adopted for holding the disease in check no doubt accounts, to a marked extent, for the low percentages. Furthermore, the facts concerning the cumulative effects of the disease in Australia may be significant in this country. It is not known how long the spores of the flag smut fungus will live in the fields in the infested area, but it is known that some of them will live over winter in the soil and still be capable of germinating and infecting wheat plants.* If the fungus is able to live in the soil in this country, as it does in Australia, its effects no doubt will be cumu- lative, as they are there, provided effective control measures are not employed. SYMPTOMS Flag smut of wheat occurs in the leaf blades and sheaths, forming black stripes running lengthwise. (Figs. 1 and 2.) In the early stages these stripes are somewhat lighter than the green color of the normal leaf; later they become lead-colored and finally black because of the presence of the dark-colored spores produced by the fungus. They are commonly more noticeable in the upper leaves, and may be seen even before jointing is apparent in the plants. The stems (culms) often show these black stripes also. Infected plants usually are more or less dwarfed. The leaves and sheaths become twisted in some cases, and the infected culms rarely head out or produce seed. Where heads do appear on infected culms, the black stripes may be present on the glumes at the base of the head and usually are present on the culms just below the head. One or more sound culms with normal Unpublished data furnished by Miss M. A. Griffiths, Office of Cereal In- vestigations, U; S. Department of Agriculture. 19SS] FLAG SMUT OF WHEAT 515 heads often may be found on smutty plants, but it is not uncommon to find infected plants without a single sound culm. The degree of culm infection seems to vary with the variety. Stem smut of rye, with which flag smut was formerly thought to be identical, differs from it in that the rye disease is most noticeable on the culms, which it more or less distorts, while the leaves show prac- tically no distortion and the culms generally produce heads even tho they are not well filled. It is caused by a different tho related or- ganism, as is shown below, and will not pass from rye to wheat. THE CAUSAL FUNGUS (Urocystis tritici Kcke.) Flag smut of wheat is caused by a minute parasitic plant, or fungus, belonging to the group of fungi which produces the disease of plants commonly known as smut. More familiar examples of dis- eases caused by this type of fungus are loose smut and bunt of wheat and the loose and covered smuts of oats. More closely related, how- ever, are the smut of onions, which causes considerable damage to the onion crop of the United States, and the stem smut of rye, which is less destructive. Wolff, 25 in 1873, thought that the fungus causing flag smut of wheat was identical with the one causing stem smut of rye and called it Urocystis occulta Rabh., which is the rye form. Kornicke, 13 in 1877, after making a careful morphological study of the forms from wheat and rye, decided that there was sufficient differ- ence to justify making the wheat form a distinct species, so he called it Urocystis tritici Kcke. McAlpine, 10 after repeated cross inocula- tions of wheat and rye with their respective Urocystis forms, agreed with Kornicke in concluding that they were different. Previous to these studies by McAlpine the disease was reported on wheat in Japan 1 1 and India 23 as being caused by Urocystis occulta Rabh. Since McAlpine 's 16 report it has been agreed generally that the Urocystis species on wheat and on rye are different. The black stripes appearing on infected wheat plants are filled with numerous minute, dark colored spores of the fungus (Fig. 3, A), which, in mass, appear black and produce the black color of the stripes. The spores contain from one to five large cells, which are capable of germinating. These large cells are incased in an outer layer of smaller, bladder-like, sterile cells, making what is commonly termed a spore ball. These spore balls are 15 to 35 microns, or an average of 24 microns (.001 inch), in diameter. The outer protective envelop of sterile cells serves, no doubt, as an aid to dissemination by wind and water by causing the spores to float. Germination of the spores takes place by small germ tubes, or promycelia, arising from the larger, inner cells (Fig. 3, B). Gen- erally one to two, and occasionally all, of the cells in the spore ball 516 BULLETIN No. 242 [April, germinate. The promycelium, which may or may not be septate, bears at its apex two to six, more commonly three, thread-like append- ages, or secondary spores, known as sporidia. These sporidia, usually of unequal length, are at first unicellular, but may divide later into two or three cells. In some cases they grow out into variously curved filaments. These sporidia in turn germinate, producing minute, thread-like tubes, or hyphae, which, if in contact with the young wheat seedling as the seed germinates, penetrate its tender tissue. These hyphae, which scarcely can be seen with the aid of the microscope, grow up thru the tissues of the young wheat plant, from which they obtain food. In the spring, the smut fungus, after it has spread thru the tissues of the wheat and after its food supply has become some- what exhausted, begins to produce the dark colored spores, which, in mass, appear as long black stripes, so typical of the disease. With the ripening of spores, the epidermis of the leaf along the stripes breaks open, thus setting free the spores for a further contamination of seed and soil. 27 Wheat plants are attacked by flag smut chiefly from two sources. One source is thru smut spores that cling to the seed. In threshing grain from infested fields a large proportion of the spores are knocked out of the diseased plants and scattered over the grain. They also lodge in the threshing machine and later become mixed with seed threshed from clean fields. Contaminated wagon beds, grain bins, bags, or other objects with which grain comes in contact may serve as disseminating agents for the fungus. When contaminated grain is sown and germinates, the adhering spores also germinate. The germ tube penetrates the young wheat seedling, grows up thru its tissues, and appears in the spring as smut stripes in the wheat plant. The other source of infection is thru spores in the soil. McAlpine 16 proved that infested straw and manure from horses fed on diseased straw, when placed on wheat land, were sources of infection. Hamblin 9 also says: "It is known that horses and cattle fed on dis- eased hay have passed the spores uninjured and capable of germina- tion. " Putterill 21 states that the spores may be blown about by wind, carried on the hoofs of animals, or transported by irrigation water. While the latter agent would not be a factor in the present infested area and surrounding territory in this country, flood water from streams may serve the same purpose. There is no particular reason why spores may not be carried from field to field or from one locality to another on the clothes of man and by animals, including birds, and on any vehicle or exposed product leaving or passing thru the infested area, especially during and near harvest time, when abundant FIG. 1. PORTIONS OF WHEAT PLANTS SHOWING THE BLACK STRIPES CAUSED BY FLAG SMUT FIG. 2. PORTION OF WHEAT LEAF, GREATLY ENLARGED, SHOWING THE BLACK STRIPES CAUSED BY FLAG SMUT. NOTE THAT SOME OF THESE STRIPES HAVE RUPTURED 1923] FLAG SMUT OP WHEAT 519 spore material is being liberated from the diseased plants. The spores carried by these agencies may fall on land where wheat is to be sown and thus spread the disease. In fields where a diseased crop has been harvested the spores live over on the stubble and in the soil until fall. A small percentage of spores is known to overwinter in the soil at Granite City, Illinois, as previously mentioned, but it is not -known whether these spores which have overwintered will live until time for sowing wheat the next autumn. In Australia, Brittlebank 1 says, "Contamination of the soil is the most difficult problem in dealing with the control of flag smut. ' ' The climatic conditions in the infested area in this country may or may not permit the organism to live in the soil in abundance and for long periods of time, as it does in Australia. These questions remain to be answered. CONTROL MEASURES Flag smut may be held in check and reduced to a minimum by employing judicious quarantine, crop rotation, seed treatment, and other sanitary measures, and by growing resistant varieties of wheat. The soil and weather conditions under which the wheat is sown also influence the development of the disease. Certain quarantine and farm sanitation measures have been employed in the infested area in this country in cooperation with the Illinois State Department of Agri- culture. They consist in the regulation of shipments of infested grain and straw, the disinfection of farm machinery leaving the infested area, etc. The burning of infested straw and stubble, which is recom- mended in Australia, 9 - 1G would be of value in reducing the spore ma- terial present. These measures are discussed in detail in Circular No. 4 of the Illinois State Department of Agriculture, "Flag Smut of Wheat." 8 EXPERIMENTS IN CONTROL BY SEED TREATMENT The following experiments were undertaken to learn whether spores of flag smut carried on seed wheat can be destroyed by treating the seed with certain fungicides. For this purpose a lot of seed of the Harvest Queen (Red Cross) variety was thoroly smutted with viable spores of Urocystis tritici. After treating this infested seed with the different fungicides in the manner described below, it was sown in the soil in the infested area at Granite City, Illinois. The various treatments and the results obtained are shown in Table 1. A number of different strengths of copper-sulfate solution and formaldehyde were used and also a number of methods of application, but none of them proved to be more satisfactory than the strengths and methods of application commonly employed and only these latter are reported in the table. Copper sulfate was used at the rate of 1 pound to 5 gallons of water. The seed was submerged for ten min- 520 BULLETIN No. 242 [April, TABLE 1. EFFECTS OF SEED TREATMENT ON THE CONTROL OF FLAG SMUT IN HARVEST QUEEN (BED CROSS) WHEAT WHEN THE SEED WAS THOROLY SMUTTED Seed sown in soil where flag smut had occurred the previous year. Experiment plots, Granite City, Illinois. Treatment Percentage of infected plants 1920 1921 1922 3-year average Untreated 27.0 17.2 6!6 0.0 25.6 1.9 .4 .8 1.8 21.7 17.6 23.26 .26 .60 Chlorophol (.3 percent solution). Copper carbonate (dust) Copper sulfate-lime (dip) trace trace Formaldehyde (1 :320 dip) Sterilac (1:500) Sterilac (1:1000) "This name is now applied to the flag smut susceptible variety, with white glabrous chaff, red kernels, and beardless heads, which was largely grown in southern Illinois, at the time flag smut was discovered, under the name "Salzer's Prizetaker." The true Salzer's Prizetaker is beardless, with glabrous red chaff and white kernels. This white-chaffed variety is sometimes known also as "Red Cross," but this name is objectionable as there is a red-chaffed variety known by the same name. utes in this solution and then for five minutes in lime water contain- ing 1 pound of lime to 10 gallons of water. Formaldehyde was used at the rate of 1 part in 320 parts of water (1 pint in 40 gallons of water). The seed was soaked for ten minutes in this solution and then covered for four hours, after which it was spread out to dry before sowing. From the table it will be noted that, in 1922, seed from all treat- ments produced some infected plants. These infections, however, except in the case of the treatment with Sterilac, where the percentage of infection was very high, may reasonably be accounted for by the presence of spores in the soil, since the treated seed was sown in soil where flag smut had occurred in wheat the previous year. From these results it may be said, in general, that nearly all the spores carried on the seed can be destroyed by seed treatment. Copper carbonate dust, which has been used successfully in Aus- tralia 6 and in the Pacific coast states 10 - 18 for controlling bunt in wheat, gave good results in the single season it was tried. (It was used at the rate of 2 ounces per bushel of seed.) Chlorophol, an organic mercury compound of recent development, was fairly effective in destroying seed-borne spores. (The seed was soaked in a .3-percent solution of Chlorophol for one hour and dried before sowing.) Sterilac, another newly developed compound, was used without success. Of the treatments used, copper carbonate is the easiest to apply and does not cause seed injury ; rather, it sometimes appears actually to stimulate the seedlings. The grain is more easily handled during and after this dust treatment than it is when treated with copper sulfate or by other wet methods. Heald and Smith 10 have devised a W2S] FLAG SMUT OF WHEAT 521 TABLE 2. EFFECTS OF SEED TREATMENT ON THE CONTROL OF FLAG SMUT IN HARVEST QUEEN (RED CROSS) WHEAT WHEN THE SEED WAS SOWN IN SOIL HEAVILY INOCULATED WITH SPORES OF FLAG SMUT Seed treated and sown in experiment plots, Granite City, Illinois, October 4, 1921. Treatment Percentage of infected plants Percentage of smutty culms on infected plants Untreated. . 19 3 36 7 Copper sulfate-lime 13.0 38.6 Copper carbonate 16.0 32.4 machine for dusting grain which consists of a wooden drum so mounted that by revolving it the dust and grain are thoroly mixed. A re- volving barrel churn or any device which will insure a thoro mixing will serve the purpose if no special machine is available. It is very important to have the dust so thoroly applied that each kernel of wheat will be covered with a thin film over its entire surface. 1 Altho treatments with copper sulfate and lime and with copper carbonate were very successful when the seed was sown in soil where infected wheat had grown the preceding year, they failed to prevent the disease when the treated seed was sown in furrows in which spores of flag smut had been previously dusted and mixed with the soil by means of a small hand plow. To be effective under these conditions the fungicide necessarily would have to remain active until after the time the seed had germinated, when infection would take place. However, even tho the disinfectant should remain active until that time, there might be infection from the spores in the soil that were near enough the young plant to infect it but too far from the seed to be destroyed by the disinfectant. The results of this one- year study of the duration of protection by these fungicides are shown in Table 2. The amount of inoculum present in the furrows in which the grain was sown was larger than ordinarily would be expected under natural conditions; still, it shows that control by seed treatment cannot be assured where the soil becomes infested with viable spores. In accordance with quarantine regulations, commercial seed wheat sown by wheat grower's in the infested area was treated with copper sulfate and lime, yet traces of Tsmut were found in some of these fields. This, in all probability, was due to the presence of spores in the soil. Australian writers are agreed that seed treatment kills seed- borne spores but that it is less effective in controlling smut where the soil is infested. CONTROL BY CROP ROTATION Wheat sown in the infested area but in fields in which flag smut has not occurred for one or more years previously is less subject to smut 'Care should be taken in handling copper carbonate dust to prevent inhaling it, as it may cause irritation of the nose and throat. 522 BULLETIN No. 242 [April, than if sown in fields known to have been infested the preceding year. Because of the fact that the spores easily survive the summer and are present to infect fall-sown wheat, it is especially important that fields growing smutty wheat be sown to other crops the following year. McAlpine, 16 Brittlebank, 1 and Hamblin 9 of Australia, and Putterill 21 of South Africa all recommend crop rotation as a means of reducing the amount of flag smut to a minimum. There are some indications from survey records 8 that rotation will be of some value in this country, as fields in the infested area which previously had grown crops other than wheat were found to have less flag smut than fields which had been cropped to wheat for a number of years and in which flag smut was known to occur. These records indicate that the effects of flag smut in this country, as in Australia, may be cumulative when susceptible wheat is grown continuously on infested land. Whether or not smut spores can survive in the soil thru the second year and infect a wheat crop when the land has not grown wheat for one year remains to be determined. Final advice concerning rota- tions, therefore, cannot be given at this time. However, it is evident that at least one year should intervene between wheat crops on the same land, and it is probable that two or more years must pass before the land is entirely free of viable spores. Inasmuch as this disease does not affect other crops than wheat, no limitation is imposed, so far as the disease is concerned, as to what crops should be grown in the rotation. However, straw, manure, or other material that may contain smut spores should not be returned to the soil in the mean- time, as infection may come from these sources. A straw mulch on potatoes, for example, may add the smut spores to the soil. If manure or other material that possibly may contain the smut spores is to be applied, the safest place in the rotation to apply it is on the wheat stubble. EXPERIMENTS IN CONTROL BY DATE OF SEEDING Wheat sown early in the fall is more subject to infection by flag smut than that sown later. According to Australian writers 1 - 9 > 16 early and self-sown (volunteer) wheat suffers most from flag smut. They also state that wheat sown in dry soil is more subject to the disease than wheat sown following a rain. This, they claim, is be- cause of the fact that during a dry season the spores remain unger- minated in the soil and when the rains come both spores and seed germinate and infection of the seedlings takes place, while, on the other hand, if the wheat is sown after the rain the spores in the soil have had time to germinate and become exhausted before the wheat germinates. In order to determine the effect of the time of sowing on the development of flag smut in wheat at Granite City, Illinois, seed of a WSS] FLAG SMTTT OF WHEAT 523 large number of varieties was smutted with spores of flag smut and sown on different dates. During the first two years of the experiment all these varieties behaved relatively in about the same way so that in the third and last year only the most susceptible variety, Harvest Queen (Red Cross), was used. The effect of the date of sowing on this variety is shown in Table 3. TABLE 3. EFFECT OF DATE OF SOWING ON THE SMUT INFECTION OF HARVEST QUEEN (RED CROSS) WHEAT, A HIGHLY SUSCEPTIBLE VARIETY Seed inoculated and sown in experiment plots at Granite City, Illinois. Date of sowing Percentage of infected plants 1920 1921 1922 Average for 2 or 3 years October, 4 to 12 32.73 15.50 24.70 27.20 6.25 5.29 .55 0.00 0.00 28.21 10.87 4.99 . .27 0.00- October 15 to 20 November 1 to 10 4.70 November 15 to 20 0.00 November 23 to 30 0.00 April 4 Wheat sown early in October smutted more than wheat sown later in the fall. There was little difference, however, in the amount of smut in sowings made sufficiently early to insure a good crop of grain. Sowings made after the first of November showed much less smut than earlier sowings. Sowings made after the middle of No- vember were smut-free, but the yields were very low. Spring-sown smutty seed produced a smut-free crop. This failure of wheat sown in late fall or in spring to become infected doubtless is due largely to the fact that soil temperatures at that time are too low for spore germination and infection. Fields of spring wheat in the infested area, other than the experimental plots, were examined but no flag smut was found. These results indicate rather decisively that tem- perature is one of the important factors in spore germination and infection. VARIETAL RESISTANCE The discovery of varieties of wheat which are desirable com- mercially and at the same time are resistant to flag smut offers the most promising means of controlling the disease. McAlpine 16 dis- cusses the possibility and desirability of producing resistant varieties in Australia. Pridham 20 found considerable varietal differences in the field infection of some of the Australian wheats. He did not smut the seed before sowing, however, so these varieties might not have been equally exposed to infection. Brittlebank, 1 in 1920, sug- gested breeding wheat for resistance to the disease. 524 BULLETIN No. 242 [April, EXPERIMENTAL WORK TO DETERMINE VARIETIES COMPLETELY RESISTANT In the fall of 1919, seed of several varieties of wheat was thoroly smutted with spores of the flag smut fungus and sown in the infested area at Granite City, Illinois. In the fall of 1920 several other varie- ties were added to the list. In 1921 those varieties which had shown more than 3 percent of smut were dropped from the list and only the more resistant wheats were sown. Among these varieties which were grown two or three years several remained free from flag smut even tho the seed was heavily smutted before sowing. A still larger number of varieties developed less than 1 percent of smut, while the remaining varieties were more or less susceptible. The seed was sown between October 4 and 12 each year. Table 4 contains a list of varieties which showed no infection dur- ing two or three years' experiments. For the present purpose, the varietal names under which the various samples were collected have been retained, but they are grouped in the following tables under varie- ties to which, upon careful examination, they were found properly to belong. Hard Red Winter Wheats. Considering first the hard red winter wheats listed in Table 4, it should be stated that all those listed are probably about equal in adaptation for growing in the area where flag smut is found in Illinois, altho Kanred probably should have preference on account of its good performance in Kansas and the availability of certified seed. From the farmer's standpoint, however, the hard red wheats are not fully desirable. This class of wheat is not so well adapted to this section of Illinois as are the soft red wheats. A considerable acreage of hard red winter wheat was sown by farmers in the fall of 1921 and some good yields were reported in 1922. The season favored these wheats to some extent, as it was favorable to severe leaf rust development, and these wheats are resistant to this rust. It is reported, however, that very little was sown in the fall of 1922. The lack of interest in these wheats probably is due to the presence of beards and to their weak straw, which, in wet seasons, causes lodging on low land. The quality of grain, also, from this class of wheat is not of the best, when grown on wet lowlands, as there is a tendency toward ' ' yellow berry, ' ' which is undesirable from the market standpoint. For the reasons stated these hard red wheats are considered undesirable for the present flag smut area in Illinois and Missouri. Soft Red Winter Wheats. Varieties of soft red winter wheats have been grown almost exclusively by farmers in the flag smut sec- tion. All those listed in Table 4 probably would be adapted for growing there, with the certain exception of Squarehead Master and 10 23] FLAG SMUT OF WHEAT 525 TABLE 4. VARIETIES OF WHEAT WHICH REMAINED FREE FROM FLAG SMUT WHEN GROWN FROM SMUTTED SEED FOR Two OR THREE YEARS AT GRANITE CITY, ILLINOIS Seed sown between October 4 and 12. Variety Source or C. I. No.' Years tested Hard Red Winter Kanred Kanred Kansas 2 Kanred Illinois 2 P-1068 5880 2 Turkey Illinois 12-41 Illinois 2 Soft Red Winter Beech wood Missouri 2 Fulcaster Eversole 3011 2 Marvelous Indiana 2 Stoner Virginia 2 Grandprize (St. Louis Grandprize) Imperial Amber 5627 3447 3 3 Penquite (Velvet Chaff) 3068 2 Red May Early Harvest 4852 2 Red Rock 5597 3 Shepherd 6163 3 Squarehead Master 3283 3 Ulta No. 834" 5747 2 Seed of varieties with C. I. Nos. was furnished by the Office of Cereal In- vestigations. Where a state is given as the source, the seed was obtained from the experiment station of that state, with the exception of Marvelous, the seed of which was obtained from a farmer in Indiana. b The variety recorded here as Ulta No. 834 is beardless with red glabrous chaff and red kernels. The name Ulta is usually applied to a variety of the Turkey type. the possible exception of a strain known as Ulta No. 834. The most desirable varieties from the local farmer's standpoint are Beechwood, Early Harvest, and Shepherd, as they are beardless and produce a good quality of soft red grain. They also yield well in this section of the country. Unfortunately, there is no commercial supply of seed of the three varieties last named. * Shepherd is being increased as rapidly as possible, however, from nursery stocks. At least 8 bushels were grown in 1922 on a farm near Granite City, Illinois, and this seed was sown on the same farm in the fall of 1922. A small plot of this wheat was sown also on another farm near Edwardsville, Illi- nois, and an increase plot was sown on Arlington Farm, Rosslyn, Virginia, from nursery supplies available. Shepherd is known also to be immune from rosette disease." Up to the present time the seed The information given here and in the following pages concerning the be- havior of varieties toward the rosette disease is derived from unpublished data furnished by H. H. McKinney and R. W. Webb of the Office of Cereal Investiga- tions, U. S. Department of Agriculture. 526 BULLETIN No. 242 [April, supplies of Early Harvest and Beechwood have not been increased, altho these varieties are likely to be satisfactory. Early Harvest has been immune from rosette disease in experiments in this locality; Beechwood has not been tested in the experiments with rosette. Ulta No. 834 represents a selection concerning which little is known. Among the bearded wheats listed in Table 4, Fulcaster (Stoner or Marvelous, C. I. No. 2980) should probably be given preference. Seed of this variety is available in commercial quantities from seedsmen and farmers. The seed of Eed Rock also is available. Large stocks are in the hands of farmers in Michigan and to a lesser extent of farmers in other states and it is also handled by seedsmen. Eversole and Imperial Amber probably are desirable varieties but the value of Penquite (Velvet Chaff) is doubtful, altho none of these three have been tested for yield in this section. All the above-named bearded varieties have been found to be immune from the rosette disease with the exception of Imperial Amber and Penquite (Velvet Chaff), which have not been tested. VARIETIES APPARENTLY HIGHLY RESISTANT In Table 5 are listed the varieties of wheat which showed less than 1 percent of smut when grown from smutted seed in the two and three years' experiments. Apparently they are highly resistant to flag smut. The small percentage of infection shown may represent, in some cases, accidental mixtures in the stocks used. Several excellent wheats appear in this list and of some of them commercial seed sup- plies are available. One group of bearded wheats with glabrous white chaff, purple straw, and red kernels embraces a number of varieties. Bearded Purplestraw, Dietz, Fulcaster, Lancaster, Mammoth Red, Nigger, and Stoner are practically synonymous names. They are of the Fulcaster type. The high resistance of these strains, coupled with the fact that Eversole and Stoner (Marvelous) are found in Table 4, among the varieties which showed no infection, indicates that this variety group is at least highly resistant to flag smut. Most of them are also immune from rosette disease, the only possible exceptions being Nigger (C. I. No. 5689) and Bearded Purplestraw, which have not been tested for rosette resistance. A pure-line strain of Nigger (C.I. No. 5366), however, descended from a single plant selection, is very susceptible to rosette. The Fulcaster variety is widely grown under one or another of its names, and there are available in Illinois and Missouri stocks of pure seed practically sufficient to sow the entire flag smut area, if such a course were necessary. Some of these commercial stocks are FIG. 3. SPORES OF Urocystis tritici Kcke. A, Photomicrograph showing the spore balls as they appear under the microscope. Magnified approximately 230 diameters. B, Drawing showing germinating spores of Urocystis tritici, Kcke. Note the promycelium bearing two or three secondary spores, or sporidia, at the apex. Magnified approximately 460 diameters. 19 25] FLAG SMUT OF WHEAT 529 TABLE 5. VARIETIES OP WHEAT SHOWING A TRACE OF FLAG SMUT BUT AVERAGING LESS THAN 1 PERCENT WHEN GROWN FROM SMUTTY SEED FOR Two OR THREE YEARS IN THE EXPERIMENT PLOTS AT GRANITE CITY, ILLINOIS Variety Source or C. I. No.' Years tested Arcadian (Early Arcadian) 3390 3 Beloglina . 5786 2 Brown Fife 1933 2 Flint Little Red 6349 2 Fulcaster Bearded Purplestraw 1911 3 Dietz . . ' Missouri 2 Dietz 1981 3 Dietz 3387 2 Fulcaster Tennessee 2 Fulcaster 2 Lancaster-Fulcaster 1945 3 Stoner" 2980 3 Genesee Giant 1744 3 Gipsy Gipsy 5579 3 Gipsy 3440 2 Reliable 3508 2 Goens Miller's Pride 4865 2 Jones Paris Prize 3568 2 Mammoth Red 2008 3 Mediterranean Mediterranean 1395 2 Mediterranean 3467 2 Missouri Bluestem 1912 3 Missouri Bluestem 1912-2 3 Nebraska No. 28 5147 3 New Amber Longberry 1973 3 Nigger 5689 2 P-1066 5879 2 Penquite (Velvet Chaff) 2 Pesterboden Budapest 5789 3 Poole 3489 3 Red May Michigan Wonder 5589 3 Red Cross 3579 2 Red May 5596 2 Red Rock b 5976 3 Rural New Yorker No. 6. . . .- 3515 3 Turkey Malakof 5-460 Illinois 2 Turkey 10-110 Illinois 2 World's Champion Illinois 2 Valley Valley... 5658 2 Indiana Swamp 5969 2 Windsor (Extra Early Windsor) 3345 3 "Seed of varieties with C. I. Nos. was furnished by the Office of Cereal In- vestigations. Where a state is given as the source, the seed was obtained from the experiment station of that state. b The slight infection of this lot of Stoner and of Red Rock may be due to accidental mixture, as other lots of these varieties and of Marvelous, a synonym of Stoner, are found in the immune list (Table 4). 530 BULLETIN No. 242 [April, being tested in the plots sown in the fall of 1922, and data will be available on them before the next harvest. Furthermore, field tests of Fulcaster wheat made in southern Illinois show it to be one of the varieties best adapted for that section. It is also an excellent milling wheat for bread flour. The bearded heads probably are the principal obstacle to its adoption by farmers in this section. Mammoth Red wheat is "grown in Maryland, where it has been distributed by the Maryland Agricultural Experiment Station to farmers of that state. It has become considerably mixed, however, and the pure seed stock, so far as known, can be found only in small quantities. About 8 bushels of Mammoth Red were produced in the flag smut area this year from seed furnished from nursery stocks by the U. S. Department of Agriculture, and this, and an additional 6 bushels furnished by the Maryland Station, was sown in the fall of 1922 in this area. Another small plot also was sown in this area from nursery stocks. With proper handling there should be sufficient seed of this variety for extensive sowings in a few years. This variety, like others in this group, is immune from rosette disease. The varieties Gipsy, Reliable, and Valley, which appear in Table 5, probably are well adapted to the area in question. They are much like the Fulcaster group in appearance, but do not have purple straw. They are important wheats in some sections of Ohio, Illinois, and Indiana. Reliable has proved immune from rosette, but the other two varieties have not been tested. A group of bearded wheats having glabrous red chaff and red kernels, of which Mediterranean is the principal variety, probably would be found to be adapted to this area. Red Rock and Miller's Pride belong to this group. Miller's Pride is highly susceptible to rosette disease, however, while Mediterranean is slightly susceptible. Red Rock appears to be immune. The Red May group of beardless wheats with glabrous red chaff and red kernels shown in Table 5 includes Michigan Wonder, Red Cross (C. I. No. 3579), and Red May. They are similar in appear- ance to Shepherd and other varieties listed in Table 1. They would be adapted to the flag smut section and appear to be immune from rosette disease. Poole (C. I. No. 3489) is similar in appearance and adaptation to this group but it has not been tested in rosette experiments. Other varieties appearing in Table 5 are either hard red winter wheats or are of other types not considered desirable for growing in this area. WHEAT VARIETIES GENERALLY GROWN IN THE FLAG SMUT AREA Wheat is grown very intensively in Madison and St. Clair coun- ties. In 1919 (Census data) wheat occupied 38.2 percent of the im- 19*3] FLAG SMUT OP WHEAT 531 proved land on the farms of Madison county and 41.7 percent in St. Clair county. Of the acreage of all land in crops, wheat occupied 45 and 47 percent, respectively, in these two counties. This must mean that wheat frequently follows wheat in the rotation and that wheat fields are practically contiguous or only slightly separated one from another over almost the entire area. Both these conditions favor the development and spread of flag smut and other diseases and also lead to their accumulation in the soil. Inasmuch as wheat is such an important crop in this area, it is not practicable to discontinue growing it in order to combat the disease. In Table 6 are given the results of an experiment to determine the susceptibility of the principal soft red winter varieties now grown by farmers in the flag smut area. All of them were found to be more or less susceptible to the disease. Harvest Queen (Red Cross or Salzer's Prizetaker), which is most suspectible, fortunately has al- TABLE 6. WHEAT VARIETIES GROWN COMMERCIALLY IN THE INFESTED AREA, ALL OP WHICH ARE SUSCEPTIBLE TO FLAG SMUT AND SHOULD NOT BE SOWN IN THIS AREA Variety Number of selections Average percentage of smut Number of years tested Flint (May) Average of two selections. . . . 20 4 1 Fultz Average of several selections . 9.5 2 Harvest Queen (Salzer's Prizetaker or Red Cross) Average of several selections 23 77 3 Jones Fife Average of two selections .... 6.97 2 Red Wave Averace of several selections . 4.27 2 most disappeared from the worst infested section, since the farmers have seen how heavily it smuts. Red Wave and Fultz are still widely grown. The use of resistant varieties, especially those varieties that have shown immunity in the flag smut experiments, offers the most effective means of control. It is possible that by the use of these varieties, kept pure and free of susceptible mixtures, the disease may be en- tirely eradicated. INDEX OF ALL WHEAT VARIETIES TESTED SHOWING RESISTANCE AND SUSCEPTIBILITY TO FLAG SMUT All varieties of wheat which have been grown in these experiments on resistance to flag smut are listed in Table 7, with a record of the annual infection and the average infection for the two or the three years during which they were tested. This table contains not only all the varieties recorded in the preceding tables, but many susceptible varieties not presented before. 532 BULLETIN No. 242 [April, TABLE 7. COMPLETE LIST OP WHEAT, SPELT, AND EMMER VARIETIES GROWN FROM SEED INFESTED WITH FLAG SMUT, SHOWING HEAD AND KERNEL CHARACTERS AND SUSCEPTIBILITY TO SMUT: EXPERIMENT PLOTS AT GRANITE CITY, ILLINOIS, 1920-1922 Crop and variety Source or C. I. No.* Description Percentage of infected plants Head b Ker- nel 1920 1921 1922 Average for 2 or 3 years WHEAT Acme 3115-2 4848 3390 1942 Missouri Illinois 1933 180 180 5342 5955 2906 3326 3484 3614 6161 Illinois 3384 3396 3608 Granite City 6349 Granite City Granite City Granite City Granite City Granite City BRG ARG ARG BWV ARG BWG ARV ARG ARG ARG AWG ARG ARG ARG BRG ARG ARG BWG BRG BWG AWG AWG AWG AWG AWG AWG AWG SR SR W SW SR HR SR SR SR SR SR SR SR SR SR W W W SR SR SR SR SR SR SR SR SR 1.6 trace 14.6 1.4 0.0 9 2 '4'9 0.0 8.10 3.15 trace Ahrens Arcadian (Early Arcadian) Bearded Winter Fife .... Beech wood '".3 trace 5.0 11.1 0.0 2.2 0.0 3.2 0.0 2.0 0.00 2.10 .15 1.60 Beloglina Brown Fife China China China (Seed from Tenn.) Pennsylvania Bluestem. Climax K. B. No. 2 .9 2.5 1 4 4.7 2.80 6.80 Currell (Currell's Prolific) . Currell (Currell's Prolific) . Currell (Pearl Prolific) .... Currell X Diehl-Mediter- ranean 1.4 4.0 3 7 2.70 0.0 3.5 0.0 6.6 .4 Dawson (Dawson's Golden Chaff) 8.1 17.5 12.5 7.3 5.80 6.25 6.95 Dawson (Dawson's Golden Chaff) Democrat Diehl-Mediterranean Eclipse Diehl-Mediterranean X Jones Fife . ... Flint Indiana May 13.4 0.0 24 " .7 '!35 Little Red May May 16.8 16.5 11.9 13.7 ;::: Red May Red May Red May "Seed of varieties with C. I. Nos. was furnished by the Office of Cereal In- vestigations. Where a state is given as the source, the seed was obtained from the experiment station of that state, with the exception of ten lots from Indiana, as follows, which were obtained from farmers: Burbank Super, Harvest King (two lots), Marvelous, Michigan Amber, New York No. 10, Poole, Red Chaff, Red Wave, and Rudy. Varieties with Granite City given as a source were col- lected from farmers in the vicinity of that city in Illinois. b A = awnless B bearded W = white or yellow chaff B = red or brown chaff Bl = black chaff Q = glabrous chaff (not velvety) V = velvet or pubescent chaff c R = red W white H = hard S - soft 198S] FLAG SMUT OF WHEAT 533 TABLE 7. Continued Crop and variety Source or C. I. No. Description Percentage of infected plants Head Ker- nel 1920 1921 1922 Average for 2 or 3 years Red May Granite City 1911 1911-1 1981 Missouri 3387 1981 3011 Missouri 3013 Tennessee 6162 AWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG AWG AWG AWG AWG AWG AWG AWG AWG BRG BWG BWG BWG BWG BWG BWG BWG BWG BWG BWG BRG BRG BRG ARV AWG AWG AWG AWG SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR W SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR 14.2 Fulcaster Bearded Purplestraw. . . Bearded Purplestraw. . . Dietz . . . . trace .9 trace 0.0 1.6 2.2 2.5 1.0 1.4 1.1 0.0 0.0 0.0 0.0 .90 1.03 .83 .50 .70 Dietz Dietz Dietz (Seed from Tennessee) Eversole 0.0 2.1 8.2 0.0 1.2 0.00 1.65 Fulcaster Fulcaster Fulcaster trace 0.0 1.0 3.6 .8 3 7 '6!6 .5 .50 1.20 .65 Fulcaster Fulcaster Fulcaster 4862 1945 Indiana 2980 Virginia 1923 3598 3604 Missouri 3349 3423 3594 5643 1744 Missouri 5579 3440 Illinois 3439 Missouri 5307 3508 Illinois -5613 3428 4865 Indiana 6684 5627 Missouri 4882 5957 Granite Citv Lancaster-Fulcaster Marvelous trace ".'4 .8 3.3 0.0 0.0 .5 0.0 11.45 1.6 4 1.5 0.0 .7 0.0 .50 0.00 .53 0.00 6.12 2.45 Stoner Stoner Fultz Fultz Fultz Fultz Fultz 23 3 Fultz 7 9 Fultz 13 7 Fultz 10.0 Fultzo-Mediterranean .... Genesee Giant (Early Genesee Giant) 0.0 trace 3.7 0.0 3 4 1.0 1.85 .35 Gipsy Defiance Gipsy 1.3 0.0 0.0 4 1 .8 1.7 .70 .85 Gipsy. /-< Uipsv .... Gipsy 4 2 Lebanon 0.0 26 8 4.1 2.05 Niagara > . Reliable 0.0 8.5 .3 .15 Gladden Gluten 1 Goens Goens 1.3 3.8 1.5 13 3 6.6 2.55 .75 Miller's Pride Red Chaff Golden Wave 1 8 Grandprize (St. Louis Grandprize) 0.0 0.0 28 3 0.0 0.00 Harvest Queen Harvest Queen Harvest Queen 12 6 Red Cross 27.0 23.3 30.7 24.5 24.93 Red Cross 534 BULLETIN No. 242 [April, TABLE 7. Continued Crop and variety Source or C. I. No. Description Percentage of infected plants Head Ker- nel 1920 1921 1922 Average for 2 or 3 years Red Cross Illinois Granite City Granite City Illinois 4843 5406 Illinois 3447 4834 Indiana Granite City Granite City Granite City 5608 3610 3568 5146 5591 Illinois Kansas 2401 5592 Granite City 4823 5584 3472 5823 3355 2008 1974 Washing- ton 1092 5824 Missouri 3563 3565 5404 Missouri 1395 3467 Illinois 1912 1930 AWG AWG AWG BWG BWG ARG ARG BRG BRG AWV AWV AWV AWV AWV ARG ARG BWG BWG BWG BWG BWG AWG AWG BRG BRG BWG BWG AWG AWG AWV AWV AWV AWV AWV BRG BRG BRG BRG BRG BRG SR SR SR R R SR SR SR SR SR SR SR SR SR SR W HR HR HR HR HR SR SR SR SR W SR W W SR SR SR SR SR SR SR SR SR SR SR 24.7 14 1 27.2 25.95 Salzer's Prizetaker Salzer's Prizetaker Hussar (Red Hussar) Hussar (Red Hussar) Illini Chief Illini Chief 18.1 3.0 0.0 .3 5.7 7 2 3.00 Illini Chief Imperial Amber 0.0 0.0 3.2 0.0 0.00 Indiana Swamp Selection . Jones Fife Burbank Super 10 8 Jones Fife 7.2 Jones Fife 5 7 Jones Fife 7.6 Jones Fife 4.3 2.7 trace 5.2 4.75 Jones Fife X Dawson .... Jones Paris Prize 0.0 0.0 1 7 1.1 7.4 .55 2.46 Kanred Xanred Kanred Kanred 0.0 0.0 4.0 0.0 0.0 0.00 0.00 Kanred Kanred King Harvester 15 9 Leap (Leap's Prolific) .... Leap (Leap's Prolific) .... Link (Missing Link) .7 0.0 2.3 0.0 0.0 0.0 6.9 3.80 0.0 1.6 0.0 0.0 4.6 .8 4.6 .8 2.30 1.20 1.53 .26 Longberry No. 1 Mammoth Amber (mixed in 1922) Mammoth Red Martin (Martin Amber) . . Martin (Martin Amber) . . Mealy Mealy 7.1 7.5 6.4 7.30 Mealy Mealy 12 1 Mealy 15.8 Mealy 4 9 M editerranean Mediterranean 1.8 0.0 0.0 3 6 1.4 .7 .3 1.6 .35 .15 Mediterranean Mediterranean Mediterranean . . Missouri Bluestem 0.0 8.2 2.5 7.2 .3 .90 7.70 Rockv Mountain . . 1923} FLAG SMUT OP WHEAT 535 TABLE 7. Continued Crop and variety Source or C. I. No. Description Percentage of infected plants Head Ker- nel 1920 1921 1922 Average for 2 or 3 years Missouri Bluestem (Selection) 1912-2 5147 1973 3361 Indiana 5689 3481 5879 5880 5629 3068 5789 Illinois Illinois Missouri Indiana Indiana Granite City Granite City 4859 1979 3489 Tennessee Indiana 1733 5370 3339 5638 4871 1915 -1957 5640 4852 Missouri 5319 3399 Indiana Illinois 5589 4868 3492 3579 5596 BWG- BWG BRG BRG BWG BWG BWG BWG BRV BRV BRV BWG BWG BWG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG AWG AWG AWG AWG AWG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG ARG SR R W W SR . W HR HR SR SR SR HR HR HR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR 0.0 .3 trace 0.0 1.2 .8 4 6 .3 .3 0.0 .10 .60 .26 Nebraska No. 28 New Amber Longberry New Amber. Longberry . New Amber Longberry . New York No. 10 5.8 Nigger '6^6 1.4 8.8 .5 0.0 8 0.0 '6!6 0.0 .70 4.40 .25 0.00 Oatka Chief P-1066 P-1068 Penquite (Velvet Chaff) Velvet Chaff Velvet Chaff 0.0 0.0 0.0 0.0 2.7 5 8 1.0 0.0 .3 3.1 .50 0.00 .10 2.90 Velvet Chaff Pesterboden Budapest Hungarian Pesterboden . . Poole 2.0 Harvest King Harvest King .... Harvest King . 4 1 Harvest King 8.8 Harvest King 17 6 Hedge Prolific. . 4 3 Poole .6 trace 0.0 1.8 0.0 2.6 3 1 2.6 0.0 5.8 1.66 trace 2.80 Poole Poole Poole Poole Type (Selection) . . Portage 2.4 4.1 6 3 3.25 Prosperity (American Bronze) 0.0 Prosperity (American Bronze) 6.5 Purdue No. 1 7.2 3.2 0.0 12.1 9.6 10 4 6.0 3.00 9.65 6.45 Purplestraw Purplestraw Purplestraw Red Clawson Early Red Clawson .... Red May Early Harvest 0.0 1 3 0.0 0.00 Early Ripe Early Ripe 2 5 Enterprise 7 1 Michigan Amber 2 9 Michigan Amber 9 Michigan Wonder 1.2 .9 2.5 7 0.0 0.0 .70 1.25 Orange Pride of Indiana . . Red Cross 'o.'o 0.0 1.9 1.8 .90 .95 Red Mav. . 536 BULLETIN No. 242 [April, TABLE 7. Continued Crop and variety Source or C. I. No. Description Percentage of infected plants Head Ker- nel 1920 1921 1922 Average for 2 or 3 years Red Rock Red Rock 5976 5597 Illinois 5582 Indiana Illinois Granite City Granite City Granite City 5693 5599 Indiana 5343 3515 5736 5737 6163 3283 Granite City 3527 Illinois Illinois Illinois Illinois 5603 Illinois Illinois Illinois Illinois Illinois 5747 5969 Illinois 5658 4846 3135 3345 4878 Tennessee 5696 2907 BRG BRG /BRG \BWG ARG ARG ARG ARG ARG ARG ARG BWG BWG ARG ARG ARG ARG ARG ARG BWG BWG BWG BWG BWG BWG BWG BWG AWG BWG BWG ARG BWG /BWG \BRG BWG ARG BWG ARG ARG AWG AWG SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR SR HR HR HR HR HR HR HR R HR HR SR SR SR SR SR SR W SR SR SR trace 0.0 0.0 0.0 3 7 .7 0.0 .23 0.00 Red Rock Red Rock (mixed) Red Wave Red Wave trace Red Wave 5.2 4.0 3 3 1.1 2.8 3.15 3.40 Red Wave : Red Wave Red Wave 4 8 Red Wave . ' 6.7 Rochester (Rochester Red) Rudy Rudy 10 1 2 3 Rudy 1.3 Rupert (Rupert's Giant) . Rural New Yorker No. 6 Rural New Yorker No. 6 Rural New Yorker No. 6 Russian 2.7 trace 4.0 0.0 8 1 2.6 3.35 0.86 1 3 Shepherd 0.0 0.0 0.0 0.0 18 0.0 0.0 0.00 0.00 Squarehead Master Texas Red Treadwell trace 0.0 .5 0.0 .4 3 5 8.2 0.0 0.0 0.0 2.75 .25 0.00 .20 Turkey Illinois 10-110 Illinois 12-41 Malakof No. 5-460. . . . Minnesota Reliable .... Turkey Turkey 0.0 2.0 2.3 2.3 2.7 1.3 0.0 1.6 5 8 .3 1.5 1.5 1.4 .4 0.0 1.15 1.90 1.90 2.05 .85 0.00 .80 Turkey Hybrid No. 402 Turkey Hybrid No. 509 Turkey Hybrid No. 514 World's Champion Ulta No. 834 Valley Indiana Swamp Indiana Swamp (mixed) Valley 1.8 .6 .30 Wheedling White Bearded 2 9 Windsor Extra Early Windsor. . . Winter Chief trace 6!6 0.0 0.0 3.4 6.6 21.2 0.0 2.9 trace 1.45 1.70 Woods Wyandotte Wyandotte Red Zimmerman . . WSS] FLAG SMUT OP WHEAT TABLE 7. Concluded 537 Crop and variety Source or C. I. No. Description Percentage of infected plants Head Ker- nel 192,1 1921 1922 Average for 2 or 3 years SPELT Alstroum 1773 1724 1772 AWG BWG ARG SR SR SR 0.0 0.0 0.0 0.0 0.0 0.0 0.00 0.00 0.00 Bearded Winter Red Winter EMMER Black Winter 2337 BB1V R .... 0.0 0.0 0.00 CONCLUSIONS Flag smut can be controlled by treatment of the seed with copper sulfate and lime or with copper carbonate, if the spores are carried only on the seed. Control by seed treatment cannot be depended on where spores are present in the soil. To be effective under these conditions the fungicide would necessarily have to remain active until the seed had germinated, for it is at the time of germination that infection from the spores in the soil takes place. However, even tho the disinfectant should remain active until that time, there might be infection from the spores in the soil that were near enough the young plant to in- fect it but too far from the seed to be destroyed by the disinfectant. The use of other crops following wheat and the careful disinfec- tion of threshing machines, wagon beds, bins, etc., which may have been contaminated tends to reduce the amount of infection. Time of planting is one of the important factors in spore germi- nation and infection. Unfortunately, however, when wheat is sown late enough in the fall to escape infection, the risk of loss in produc- tion is too great to make this a practical means of control. The discovery of varieties of wheat which are desirable commer- cially and at the same time are resistant to flag smut offers the most promising means of controlling the disease. The results of experi- ments so far conducted show fourteen varieties or strains to be immune and forty-one others to be highly resistant. If wheat grow- ing were discontinued for a number of years thruout the infested area and all volunteer wheat were destroyed the disease might be eradicated, but even this is not certain. The ultimate solution probably will be the using of resistant varieties. 538 BULLETIN No. 242 LITERATURE CITED 1. BRITTLEBANK, C. C. Flag smut. Jour. Dept. Agr. Victoria, 18, 4, 240-243. April, 1920. 2. BRITTLEBANK, C. C. Seed-borne diseases, "take-all and flag smut." Jour. Dept. Agr. Victoria, 19, 7, 447. July, 1921. 3. COBB, N. A. Smut. Agr. Gaz. N. S. Wales, 2, 672. 1891. 4. DARNELL-SMITH, G. P. Flag smut of wheat. Agr. Gaz. N. S. Wales, 25, 4, 285-287. April, 1914. 5. DAKNELL-SMITH, G. P., and Eoss, H. A dry method of treating seed wheat for bunt. Agr. Gaz. N. S. Wales, 30, 10, 685. October, 1919. 6. DARNELL-SMITH, G. P., and Eoss, H. Fungicidal dusts for the control of smut. Agr. Gaz. N. S. Wales, 32, 796-798. 1921. 7. DARNELL-SMITH^ G. P., and MACKINNON, E. Fungus diseases of wheat. Dept. Agr. N. S. Wales, Farmers' Bui. 102, 14-19. 1915. 8. GLENN, P. A., et al. Flag smut of wheat. 111. Dept. Agr. Circ. 4. 1922. 9. HAMBLIN, C. O. Flag smut and its control. Agr. Gaz. N. S. Wales, 32, 23. 1921. 10. HEALD, F. D., and SMITH, L. J. The dusting of wheat for bunt or stinking smut. Wash. Agr. Exp. Sta. Bui. 168. June, 1922. 11. HORI, S. Seed infection by smut fungi of cereals. Bui. Imp. Cent. Agr. Exp. Sta. Japan, 1, 2, 171-172. 1907. 12. HUMPHREY, HARRY B., and JOHNSON, AARON G. Take-all and flag smut, two wheat diseases new to the United States. U. S. D. A. Farmers' Bui. 1063. 1919. 13. KORNICKE, F. Mykologische Beitrage. Hedwigia, 16, 33-34. 1877. 14. KUEIIN, J. Mittheilungen iiber die Entwickelungsformen des Getreidebrandes und die art des Eindringens der Keimfaden in die Wahrpflanze. Bot. Zeit., 32, 122. 1874. 15. McALPiNE, D. Flag smut of wheat. Jour. Dept. Agr. Victoria, 3, 168-169. 1905. 16. MCALPINE, D. The smuts of Australia, 88-102. 1910. 17. M^CKIE, W. W. Quarantine against "flag smut" and "take-all." Mo. Bui. Dept. Agr. Calif., 8, 8, 456-460. 1919. 18. MACKIE, W. W., and BRIGGS, F. N. Fungicidal dusts for the control of smuts. Science, n. s., 52, 540. 1921. 19. PEACOCK, E. M. Field experiments with flag smut. Agr. Gaz. N. S. Wales, 24, 381-384. 1913. 20. PRIDHAM, J. T. Flag smut of wheat. Agr. Gaz. N. S. Wales, 24, 25-26. 1913. 21. PUTTERILL, V. A. Flag smut of wheat. Jour. Dept. Agr. Union So. Africa, 1, 252-257. 1920. 22. EEED, GEORGE M., and DUNGAN, GEORGE H. Flag smut and take-all. 111. Agr. Exp. Sta. Circ. 242. 1920. 23. SYDOW, H. et P., and BUTLER, E. J. Fungi Indiae orientalis. Ann. Mycol., 4, 427. 1906. 24. TISDALE, W. H., and GRIFFITHS, MARION A. Flag smut of wheat and its control. U. S. D. A. Farmers' Bui. 1213. 1921. 25. WOLFF, E. Der Brand des Getreides, 16-17. Halle, 1873. Papers ivhich have appeared since the preparation of this manuscript : 26. MIYAKE,' I. Studies in Chinese fungi. Bot. Mag. Tokyo, 26, 303, 51-66. 1912. Unpublished translation by W. T. Swingle, 1923. 27. NOBLE, E. J. Studies on Urocystis tritici Koern., the organism causing flag smut of wheat. Phytopath., 13, 3. March, 1923. 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