20 
BULLETIN 70. 
EXPLANATION OF PLATES. 
PLATE I. Fig. 1. Sack of potatoes examined June 3. Large pile 
contains badly diseased potatoes, slightly diseased in the center, while 
the smallest pile contains the clean potatoes. 
Fig. 2. Sclerotia of Rhizoctonici on potato. Very common on seed 
potatoes. 
Fig. 3. Surface of potato covered by net work of fine cracks 
caused by attacks of Rhizoctonici. Figs. 2 and 3 natural size. 
PLATE II. Fig. 1. Potato badly scarred by Rhizoctonici. Much 
of the so-called scab is undoubtedly due to this disease. 
Fig. 2. Potato sprouts killed in the sack by the fungus. From 
the sack shown in Plate I. Both figures natural size. 
PLATE III. Showing how Rhizoctonici attacks young plants in 
the field. Two on the right were killed before reaching the surface of 
the ground. The others badly injured. Natural size. 
PLATE IV. Potato sprouts from sack. Some killed by and 
others showing sclerotia of Rhizoctonia. Enlarged. 
PLATE V. Plant from which potatoes were all cut off by Rhi¬ 
zoctonia, producing an abnormally large top. 
PLATE VI. Large vine from which all but a few small potatoes 
were cut off by the fungus. 
PLATE VII. Potato plant infected from diseased seed; the root 
system badly injured. 
PLATE VIII. Potato plant from which the tuber stems were all 
cut off by the fungus. As a result a large top was produced and tubers 
formed in the axils of the leaves. 
PLATE IX. “Little Potatoes” and “Aerial Potatoes” produced 
by ringing the main stem. August 24. 
PLATE X. “ Little Potatoes ” and “Aerial Potatoes” produced 
by removing all potatoes twice during the season. August 24 anti Sep¬ 
tember 2. 
PLATE XI. Fig. 1. Three green potato stems inoculated with 
cultures of Rhizoctonici. One completely cut off, the others nearly girdled. 
Fig. 2. Two tuber stems inoculated as above. Both cut off by 
the fungus at the discolored point. All natural size. 
PLATE XII. Green stems inoculated with cultures of Rhizoc¬ 
tonia. One cut in two, the others badly injured. Natural size. 
EXPRESS BOOK PRINT 
FORT COLLINS, COLO 
