LESSONS ON POTATOES FOR RURAL SCHOOLS. 13 
various parts of its structure noted. What distinguishes the potato 
from the other members of the nightshade family? A study of the 
characteristics of the various types of potatoes should be made with 
a view of aiding the student to identify the different groups. 
Correlations. — Drawings of a tuber, showing parts, and of sections 
showing structure should be made. In studying the entire plant 
the student may sketch the plant or make a copy from a chart. 
Language: Look up the nightshade family of plants in a good 
reference book, and bring to class a written report on same. Make 
a written or oral report on the differences between the potato and 
tomato or other members of that family. Write an account of the 
usefulness of the nightshade family. 
LESSON VII. 
Subject. — Place of potatoes in the rotation. 
Problem. — To study the place of potatoes in a rotation in order 
that the greatest yields may be made and soil fertility maintained. 
Sources of information. — Farmers' Bulletin 365 ; a good reference 
text ; bulletins from the State college of agriculture. 
Illustrative material. — Comparative charts showing yields of po- 
tatoes grown in a rotation and those grown continuously on the same 
field; field diagram showing suggested 3-year, 4-year, and 5-year 
rotations; diagram of crop rotation with potatoes actually being 
carried out in the district. All these will make helpful illustrative 
material. 
Class exercise. — Discuss with the class the following topics show- 
ing the advantage of growing potatoes in a rotation with other 
crops : 
1. Plant diseases often become rapidly worse in the continuous 
cropping system, which has often been the case with potatoes. The 
class may be shown how modern scientific methods of care of seed 
selection, disinfection, spraying, and other details of culture some- 
what reduce this danger. 
2. In the business management of the farm rotation reduces the 
danger of excessive losses in seasons of low prices or of poor yields 
and arranges the work of the farmer through the season to better 
advantage. 
3. Weeds are more easily controlled under a system of rotation. 
The high value of the potato crop pays for thorough tillage and care 
which cleans the soil of weeds for the rest of the rotation. 
4. Insect pests are kept down more easily under rotation. 
5. The high cash value of the potato justifies considerable expendi- 
ture for fertilizers, and justifies the use of more of the time of 
the rotation in producing organic matter to be returned later to the 
