Apr. 3-sept. 35. 1916 Illustrations XI 



Page 



Plate XXXVII. Fig. i, 2, 3. — Stem-end and lenticel blackrot produced by 

 spraying the growing tubers with a spore suspension of Fusarium radicicola. 

 Idaho Rural potato tubers. Fig. 4. — Eye infection produced by spraying 

 the growing tuber with a spore suspension of F. radicicola. Netted Gem 

 tuber. Fig. 5, 6, 7. — Stem-end blackrot produced by the inoculation of 

 the stolons of growing Idaho Rural tubers. Fig. 8. — Stem-end rotof Netted 

 Gem tuber produced by inoculating the stolon of the growing tuber 310 



Comparative Study of the Root Systems and Leaf Areas of Corn and 



THE Sorghums 



Plate XXXVIII. Fig. i. — Method used in isolating root systems in the field. 

 View of two soil prisms ready for washing. Fig. 2. — Method used in isolat- 

 ing root systems. Fig. 3. — Method of washing used in the isolation of the 

 root systems 332 



Plate XXXIX. Fig. i. — Root sj^stem of a com plant that had reached a 

 height of 3 feet 6 inches. Fig. 2. — Root systems of two com plants with a 

 height of I foot 6 inches. Fig. 3. — Root system of a Dwarf milo plant at 

 the age of 4 weeks. Fig. 4. — Root systems of two BlackhuU kafir plants 

 I foot in height 332 



Plate XL. Fig. i. — Root systems of two mature com plants. Fig. 2. — Root 



system of a com plant at the time of " shooting " 332 



Plate XLI. Fig. i.— Root systems of two BlackhuU kafir plants at the time 

 they had reached a height of 6 feet and were blooming. Fig. 2. — Root 

 system of two Dwarf milo plants at the time the seed was in the milk stage. 332 



Plate XLII. Fig. i. — Portion of a primary root of Pride of Saline com, show- 

 ing the number and relative size of the secondary roots. Fig. 2. — Portions 

 of the primar)' roots of BlackhuU kafir, showing the number and relative 

 size of the secondary' roots '. 332 



Plate XLIII. Fig. i. — Pride of Saline com. Dwarf milo, and BlackhuU kafir 

 plants, showing their relative leaf and sheath areas at 4 weeks of age. 

 Fig. 2. — Pride of Saline com, Dwarf milo, and BlackhuU kafir plants, 

 showing their relative leaf and sheath areas at 6 weeks of age 332 



Plate XLIV. Fig. i. — Pride of Saline com, Dwarf milo, and BlackhuU kafir 

 plants, showing their relative leaf and sheath areas at 8 weeks of age. 

 Fig. 2. — Pride of Saline com, Dwarf milo, and BlackhuU kafir plants, 

 showing their relative leaf and sheath areas at 10 weeks of age 332 



Silver-Scurf of the Irish Potato Caused by Spondylocladium atrovirens 



Plate XLV. Fig. i. — Potato tubers showing shriveling and a silvery appear- 

 ance caused by Spondylocladium atrovirens. Fig. 2. — Tuber naturally 

 infected by 5. atrovirens, showing the segregated area type of infection. 

 Fig. 3. — Immatiu-e potato tuber artificially inoculated with conidia of 5. 

 atrovirens, July, 1913, at Houlton, Me 350 



Plate XLVI. Fig. i. — Photomicrograph of Spondylocladium atrovirens on 

 corn-meal agar, showing method of development of conidiophores and 

 conidia in the early stages. Fig. 2. — Photomicrograph of 5. atrovirens in 

 hanging-drop culture, showing development of conidiophore and conidia 

 in mature stages. Fig. 3. — Negative heliotropism of S. atrovirens on corn- 

 meal agar exposed on one side to daylight from April 8 to April 24, 1915, 

 in laboratory at room temperature 350 



Plate XLVII. Effect of temperature upon mycelial development of Spon- 

 dylocladium atrovirens in pure culture on corn-meal agar at end of four 

 weeks 350 



