34 
LABORATORY EXERCISES 
II. The Black Rust Stage. Study wheat plants showing the 
black rust stage. What part of the plant is affected by this stage? 
With a lens determine what causes the color of the black areas. 
Compare the age of the wheat plant affected by black rust with 
that of the wheat affected by red rust. (See Waggoner, Figs. 113 
and 114.) Make drawings as directed by the instructor. 
III. The Cluster Cup Stage on the Barberry. Study leaves of 
the common barberry which are affected by the cluster cup stage. 
What is the appearance of the spots upon these leaves? On which 
side of a leaf do you find these spots? Study under a lens. What 
is the relation of this stage to the other stages? Why is the com¬ 
plete eradication of the common barberry advised by the United 
States Department of Agriculture? (See Waggoner, Fig. 115.) 
Make drawings as directed by the instructor. 
IV. The Distinction between the Common and the Japanese 
Barberry. Compare specimens of the common barberry with the 
Japanese barberry as to size and form of leaves, character of 
thorns, and arrangement of fruits. (See The Black Stem Rust and 
the Barberry, E. C. Stakman, Pub. of U. .S. Dept, of Agriculture, 
No. 796, Page 18, or the Yearbook of the U. S. Dept, of Agriculture, 
1918, Page 77 ff.) Draw specimens of each. The common bar¬ 
berry is the one which acts as a host to wheat rust. The Japanese 
barberry is a useful shrub which has no relation to this disease of 
wheat and which should never be confused with the common 
barberry. (See Waggoner, Fig. 116.) 
V. Find out if possible what has been done in your state towards 
the eradication of the common barberry. Inquire of your county 
agricultural advisor or of others interested in the growing of wheat 
and oats. 
VI. Design a poster which may be effective in calling attention 
to the need of the eradication of the common barberry. 
(Note — Prepare the yeast mixture for Exercise 40 the day 
preceding that on which it is to be used.) 
