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$WI LD R LATI\IES CROP PLANTS IN INDIA$

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FIG. 1. Vstilago avenae on Arrhenatherum elatius. I I FIG. 3. Vstilago striiformis on Holcus lanatus. FIG. 2. Vstilago nuda on wheat. \ . FIG. 4. Vstilago grandis on FiG. 5. Vstilago hypodytes on Phragmites communis. Elymus arenarius. \
BIOLOGY ENTRANCE AND INVASION OF THE HOST IT seems to be generally true that smut fungi can enter the host only at points where the tissue is relatively young. Varying with the species, infection occurs through the plumule on emergence from the seed (Tilletia caries, Ustilago avenae, and others), axillary buds {U. maydis), immature leaves {Entylomaficariae), or young ovaries (Ustilago nuda). As tissues age, they become more resistant to attack and finally attain immunity, even in susceptible varieties. In oats, for example, infection by smut rarely occurs after the shoot is more than one iach in length, and onion seedlings escape attack if penetration does not occur before the first leaf emerges from the cotyledon (Walker & Jones, 1921; Anderson, 1921). Evans (1933) studied the development of Urocystis cepulae mycelium in the cotyledon, showing how its advance slowed down as the tissue approached maturity, until finally the invading hyphae failed to pass beyond the sub-cuticular layer of the outer epidermal wall. The cotyledons of onions at a critical age showed minute sub-cuticular vesicles, consisting of fungus mycelium which had pierced the cuticle and digested a portion of the cell wall but had not succeeded in. entering the cell and establishing an active infection centre. A similar response to invasion is made when highly resistant varieties of wheat, oats, and rye are attacked by certain races of smuts. Penetration of the outer wall occurs but growth does not extend beyond the epidermal cell (Woolman, 1930; Western, 1936b; Ling, 1940b). In less resistant varieties the parasite progresses for a time, even reaching the stele of the host, but fails to enter the flower primordia and does not sporulate (Sampson, 1933). This so-called 'latent infection' may aifect adversely the growth and yield of wheat varieties like Heils Dickkopf which have been regarded as immune from bunt (Zade, 1931). In susceptible varieties of our common cereals, once the smut has passed the barrier of the epidermal wall, it usually grows from cell to cell without causing necrosis or any apparent disturbance to the host. Seedlings infected by bunt can sometimes be recognized by their distorted growth and mottled foUage (Churchward, 1934; Johnston & Lefebre, 1939; Churchward, 1940), and it is not rare to find infected seedlings sensitive to winter conditions, but, normally, no external symptoms distinguish seedlings that carry the myceUum of smut fungi. The growth of the smut mycehum is, at first, both intra- and intercellular, but, after a time, more and more intercellular mycelium is found. SpeciaUzed haustoria (Fig. 20 a), common in some species, are not formed by the cereal smuts, but short hyphae can sometimes be seen penetrating the cells. Infected seedlings of susceptible varieties carry mycehum in the mesocotyl, coleoptUe, young leaves, and finally in the growing-point itself (Kolk, 1930, Sampson, 1933). Once this is reached, the fungri rarely fails to develop spores since changes in temperature, water supply, manuring, and Ught have very little restraining efi'ect (Sampson & Western, 1938; Reed, 1938). Cereal smuts, which fructify in the inflorescence, penetrate the leaves of adult plants only to a shght extent, but, where conditions especially favour the fungus, sori may develop in lines along the flag leaf. Even Tilletia caries and T. foetida wUl sometimes form ehlamydospores in wart-like galls on leaves (Plor, 1932).
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 16: ^^ THE BBITISH SMUT FUNGI Young hea
Page 19 and 20: BIOLOGY 15 less than the normal, in
Page 21 and 22: BIOLOGy 17 and united with it, fina
Page 23 and 24: BIOLOGY 19 eermination in a collect
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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