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18 THE BRITISH SMUT FUNGI and the infection of new leaves in the current season. That spores of the same species can also overwinter is shown by the infection of healthy shoots which occurs if old leaves carrying chlamydospores are Spread over the soil in spring. Setchell (1892) found that in D. alismatis most spores, from a mature sorus would germinate while still in the leaf, but dry leaves kept for nearly a year in the laboratory still contained some spores capable) of growth. In D. sagittariae and in D. occulta germination only occurs in spring, while in D. obscura it takes place in nature during October. Germination in situ is not the normal process for srhuts with dusty sori, which permit dissemination of spores, but in many species immediate germination is possible and spores are viable over a long period of time. In some species, notably the loose smut of wheat and barley which infects at flowering time, germination reaches a maximum during the summer, falls rapidly in the autumn, and is often negligible in collections only a year old. Stakman (1913), however, found no loss in viability after ten months' storage. Viability could perhaps be maintained even in this species over a longer period by controlled methods of harvesting and storage. Collections of spores of the loose smut of oats, which were allowed to mature in parchment bags, gave good germination results and remained viable for several years, while others harvested in the field soon after the emergence of the diseased panicle quickly lost their viability. In a certain collection of the covered smut of oats a maximum figure for germination was not obtained until some weeks after harvest, but once reached no falling off occurred for at least 2| years (Sampson, 1928). Davis (1924), working with Ustilago striiformis on Agroatis palustris, Phkum pratense, Poa pratensis, and Dactylis glomerata found that the spores required an after-ripening period of 240 days when stored in the laboratory, or 265 days in. the field, before giving satisfactory germination. A similar result was obtained by Kreitlow (1943 a) working with the same smut on Poa, but one collection on Agrostis gave a germination of 50 to 75 per cent, without any period of storage. Fischer (1940) also obtained good germination of fresh spores in a closely related smut collected on Agropyron pauciflorum and Elymus glaucus. Kreitlow (1943 b) reduced the need for an after-ripening period by growing the host at 32° C. and by storing smutted leaves in a moist chamber at 35° C, but results by these methods may be erratic (Leach, Lowther, & Ryan, 1946). Exposure to chloroform fumes for one minute or to a 10 per cent, citric acid solution for five minutes shortened the after-ripening period by about one month (Davis, 1924). Forms of Urocystis anemones also differ in time of germination, since Kniep (1921) found that those collected from the creeping buttercup would grow at once and infect the young leaves, while spores taken from the wood anemone, a plant that quickly dies down, germinated only in spring, when the new growth was breaking through the soil. In view of such facts it is not surprising that collections from herbaria have given variable results. Fischer (1936 b) tested for germination material from the Plant Pathology Herbarium in the State College of Washington. Among 387 specimens examined, 80 had viable spores. The most noteworthy examples of longevity were Tilletia foetida (25 years), T. caries (18 years), Ustilago hordei (23 years), U. bullata (10 years), U. avenae (13 years), Sphacelotheca sorghi (13 years), and Entyloma calendulae f. dahliae (10 years). Sobel (1933) recorded
BIOLOGY 19 eermination in a collection of U. hordei from oats 13| years old and Noble (1934) germinated Urocystis tnitici after storage at low humidity for 10 years. Fischer suggests that, on the whole, members of the Tilletiaceae survive longer than the tJstUaginaceae, but the record for viabihty is that quoted by C. S. Wang (1936) for Ustilago crameri from Setaria italica which gave 1 per cent, germination 64 years after harvest. Fischer's data from exsiccati confirm the importance of maturity as a factor in the potential life of a collection of spores. Environmental conditions, {a) Temperature. From experiments on the germination of chlamydospores of the more important economic species, it appears that growth will take place over a wide range of temperatures. In the species of Ustilago that attack the temperate cereals, the cardinal temperature points for germination fluctuate round the following values: minimum, 5° C.; optimum, 22° C.; maximum, 30° C. (Herzberg, 1895; Bartholomew & Jones, 1923; Jones, 1923 a; Novopokrovsky & Skaskin, 1925; Rump, 1926; Yen, 1937). Somewhat similar figures are given for U. striiformis (Davis, 1924). The corresponding points for certain smuts on maize and mUlet are about five or even ten degrees higher (Jones, 1923 b; Novopokrovsky & Skaskin, 1925; Lobik & Dahlstrem, 1936; Yen, 1937). Christensen (1926) found that a high temperature (28° C.) favoured the infection of sorghum by head smut. Hahne (1926) gives these figures for the two bunts of wheat; minimum 4° C.; optimum, 18°-20° C.; maximum, 36° C. Speaking generally, a low temperature (about 15° C.) favours both germination of bunt spores and infection of the host (Lobik & Dahlstrem, 1936; Hungerford, 1922; Faris, 1924 c), but the optimum temperature for infection varies with the variety (Feucht, 1932). See also Tapke (1948). Walker & Wellman (1926) found the optimum temperature for germination of chlamydospores of Urocystis cepulae to lie between 13° and 22° C. Infection of the host occurred when the soil temperature was as low as 10° C. a point near the lower Umit for the germination of onion seed, but early sowing in the state of New York helped to control the disease by reason of the relatively low (8°-13° C.) temperature of the soil (Felix, 1939). Noble (1923) obtained germination of U. agropyri from wheat over a wide range of temperature, 5°-32° C, with an optimum at 18° to 24° C. Ling (1940 a) obtained similar results with U. occulta from rye, giving the optimum as 15° C, (For the effect of temperature on the mode of germination, see pp. 56, 66.) (6) Light. For most germination tests spores are placed in dark incubators and receive light only when examined. In general, Hght has not been regarded as a critical factor for the germination of chlamydospores. Tests in hght and darkness have often given similar results (Stakman, 1913; Lobik & Dahlstrem, 1936; Ling, 1940a; Hulea, 1947). Hahne (1925) workmg with Tilletia and Kaiser (1936) with Entyloma obtained bett^er results in light. In the absence of daylight Kaiser (1936) stimulated germination by means of a fluorescent dye. Ultra-violet Hght retarded both germination and subsequent growth in Ustilago nmydis (Landen, 1939). (c) Media. See pages 24 and 40. The promycelium. The distinctive methods of germination in Ustilago and Tilletia were first recognized by Prevost in 1807. Tulasne (1847,1854) described and figured the process in several species of Ustilago, demonstrated the fusion of
Page 1 and 2: THE BRITISH SMUT FUNGI ^ (USTILAGIN
Page 3: FOREWORD THIS volume was started wh
Page 6 and 7: 6 PBEFACE We also acknowledge the b
Page 9 and 10: INTRODUCTION THE smut fungi, which
Page 11 and 12: INTRODUCTION H of bushels of wheat
Page 14 and 15: FIG. 1. Vstilago avenae on Arrhenat
Page 16: ^^ THE BBITISH SMUT FUNGI Young hea
Page 19 and 20: BIOLOGY 15 less than the normal, in
Page 21: BIOLOGy 17 and united with it, fina
Page 25 and 26: BIOLOGY 21 genus, and the manner of
Page 27 and 28: BIOLOGY 23 species of Entyloma, and
Page 29 and 30: 3036^ BIOLOGY 25 in others. Dickins
Page 31 and 32: CYTOLOGY THE discovery of nuclei in
Page 33 and 34: GENETICS INCOMPATIBILITY KNIEP'S di
Page 35 and 36: GENETICS • 31 direction of growth
Page 37 and 38: GENETICS 35 when a few sporidia fro
Page 39 and 40: GENETICS 37 lines retained their di
Page 41 and 42: TECHNIQUE COLLECTION AND EXAMINATIO
Page 43 and 44: TECHNIQUE 41 be undesirable. Weak a
Page 45 and 46: TECHNIQUE 43 in one season (see p.
Page 47 and 48: TECHNIQUE 45 barley with loose smut
Page 49 and 50: TECHNIQUE 47 (1939), Holton & Heald
Page 51 and 52: TECHNIQUE 49 Allen's, modification
Page 53 and 54: CLASSIFICATION THE morphological ch
Page 55 and 56: THE BRITISH SMUT FUNGI MOST of the
Page 57 and 58: FIG. 2. Spore geimination in Ustila
Page 59 and 60: THE BRITISH SMUT FUJJGI 57 from one
Page 61 and 62: THE BRITISH SMUT FUKGI 59 of exsert
Page 63 and 64: THE BRITISH SMUT FUNGI 61 noticeabl
Page 65 and 66: THE BRITISH SMUT FUNGI 63 Evidence
Page 67 and 68: THE BRITISH SMUT FUNGI 65 winter in
Page 69 and 70: THE BRITISH SMUT FUNGI 67 Ustilago
Page 71 and 72: THE BRITISH SMUT FUlJGI 69 material
Page 73 and 74:
THE BRITISH SMUT FUNGI 71 results o
Page 75 and 76:
THE BRITISH SMUT FUNGI 73 TTstilago
Page 77 and 78:
THE BRITISH SMUT FUNGI 75 Species i
Page 79 and 80:
" TJSE BRITISH SMUT FUNGI 77 Ustila
Page 81 and 82:
THE BKITISH SMUT FUNGI 79 On Carex
Page 83 and 84:
THE BRITISH SMUT FUNGI 81 Exsiccati
Page 85 and 86:
THE BRITISH SMUT FUNGI 83 Tilletia
Page 87 and 88:
THE BRITISH SMUT FUNGI 85 bunt ball
Page 89 and 90:
THE BEITISH SMUT FUNGI 87 globose t
Page 91 and 92:
THE BRITISH SMUT FUNGI 89 FIG. 13.
Page 93 and 94:
FIG. 15. Spore geimination in Taboi
Page 95 and 96:
FIG. 17. Spore germination in Urocy
Page 97 and 98:
THE BRITISH SMUT FUNGI 95 separate
Page 99 and 100:
THE BRITISH SMUT FUNGI 97 8ori in t
Page 101 and 102:
THE BRITISH SMUT FUNGI 99 Urocystis
Page 103 and 104:
30390 THE BRITISH SMUT FUNGI 101 pr
Page 105 and 106:
FIG. 20. Spore geimination in Entyl
Page 107 and 108:
THE BRITISH SMUT FUNGI 105 Sori in
Page 109 and 110:
On Ranunculus ficariae and B. scler
Page 111 and 112:
THE BRITISH SMUT FUNGI 109 Infectio
Page 113 and 114:
THE BKITISH SMUT FUNGI 111 [Sporidi
Page 115 and 116:
THE BRITISH SMUT FUNGI 113 Ustilago
Page 117 and 118:
REFEEENCES 115 BBETT, M. A. (1940).
Page 119 and 120:
REFERENCES 117 ^ DniON WESTON, W. A
Page 121 and 122:
REFERENCES 119 GRIFFITHS, MAEIOK A.
Page 123 and 124:
REFERENCES 121 HtjTTiG, W. (1933).
Page 125 and 126:
REFEBENCES 123 LiMBOtruN, E. J. (19
Page 127 and 128:
REFERENCES 125 NOBLE, E. J. (1934).
Page 129 and 130:
REFERENCES 127 RoDENHiSEE, H. A., &
Page 131 and 132:
BEFERENCES 129 STAKMAK, E. C, XCEEN
Page 133 and 134:
EEFEEENCES 131 WAXTBE, J. M. (1934)
Page 135 and 136:
INDEX to generic and specific names
Page 137 and 138:
Muscari Ustilago vaillantii, 59 Myo
Page 139 and 140:
Ustilago ficuum Reich., 113 —flps
Page 141 and 142:
2i}:y0 ANDHRA PRADESH AGRICULTURAL
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