TABLE OF CONTENTS. 
PAGE 
Introduction 5 
History and distribution 6 
Economic importance 9 
Symptoms 11 
Morphology of the causal organism 11 
Occurrence of the orgauism 15 
Technique 16 
Macroscopic characters 18 
The mycelium 19 
Spore septation 20 
Influence of temperature 39 
Humidity 42 
Color 42 
Conidiophores 45 
Chlamydospores 45 
Spore measurement 45 
Summary 47 
Fusarium tuberivorum sp. n. Wilcox and Link 48 
Etiology — 
Tuber infections 49 
Contact inoculation 50 
Eye punctures of Early Ohio 50 
Surface punctures of Early Ohio 50 
Surface inoculations of Early Ohio tubers after removal of the skin 51 
Smear inoculations on eye, lenticel, or surface of Early Ohio 52 
Inoculation of "new" tubers of Early Ohio 58 
Natural field inoculations . . . 59 
Natural infection with dry rot 64 
Artificial infection 65 
Comparative studies of Fusarium oxysporum and Fusarium tuberi- 
vorum 68 
Morphogenic and chromogenic influence of acidity of the medium 
upon Fusarium oxysporum and Fusarium tuberivorum 68 
Chromogenic influence of light upon Fusarium oxysporum and 
Fusarium tuberivorum 77 
Resistance and susceptibility 79 
Other inoculations 80 
Methods of control 82 
Summary and conclusions 84 
Bibliography 85 
28 plates. 
15 text figures. 
T graphs. 
1 map. 
