ILLUSTRATIONS 
PLATES 
True Nature or Spinach-Blight and Relation or Insects to Its Transmission 
Plate A. i.—A typical blighted Savoy spinach plant in the fifth stage of Page 
the disease. 2.—A healthy Savoy spinach plant.. 60 
Plate I. A.—a, A spinach plant killed by blight; 6, an apparently healthy 
plant; c , d, and e, plants in progressive stages of the disease. B.—A 
spinach field near Norfolk, Va., in which scattered blighted plants occur.. 60 
Plate 2. A.— a , Upper surface of a spinach leaf affected with downy-mildew 
(cause: Peronospora effusa), showing the light areas which might be mis¬ 
taken for early symptoms of spinach-blight, b, The under surface of a 
similar leaf. B.—Spinach leaves affected with Heterosporium leafspot... 60 
Plate 3. A.—A spinach leaf affected with anthracnose. B.—A spinach field 
showing blighted spinach plants killed by extreme cold. 60 
Plate 4. A.—A spinach plant showing the first stage of the blight. B.—A 
spinach plant showing the sixth stage of the blight.... 60 
Plate 5. A.—Improved field cage for studying spinach-blight. B.— a , 
Seventh stage of spinach-blight; b, eighth stage of spinach-blight. 60 
Plate 6. A.—Detail of the door construction of the improved field cage 
shown in Plate 5, A. B.—Cloth-covered wire cages, together with a large 
lantern globe, representative of the types of cage used for greenhouse 
experiments and for individual inoculations in the field cages. 60 
Plate 7. A.—i, Spinach plant showing blotched appearance due to chlorosis. 
2, Typical fifth-stage blighted plant. 3, Healthy plant. B.—a, Healthy 
spinach seedling pricked with a flamed needle as a control, b , A pot of 
seedlings inoculated with the virus of spinach-blight 16 days prior to the 
time this photograph was taken.... 60 
Plate 8. A.—a, A pot of spinach seedlings inoculated with virus-bearing 
aphids collected from blighted plants in the field, b, A pot of healthy 
seedlings which served as controls. B.—a, Healthy spinach seedlings 
used as a control, b, Spinach seedlings of the same age as the control, 
inoculated by needle pricks with the blight virus. 60 
PLATE 9. A.—Large area of blighted spinach on farm E, eastern Virginia. 
B.—Three spinach plants inoculated with virus-bearing Macrosiphum 
solanifolii, first instar.. 60 
PLATE 10. A.—A blighted Viroflay spinach plant from Ohio. B.—Interior of 
cage 4, in which the aphids and blighted spinach plants were allowed to 
remain.... 60 
Plate ii. A.—Interior of cage 2. B.—Experimental plots. 60 
Contribution to the Knowledge or Toxoptera graminum in the South 
Plate 12. Toxoptera graminum: A.—Outdoor breeding shelter or insectary at 
Columbia, S. C., in which the cages were kept throughout the season. 
B.—An interior view of the same. no 
(V) 
