FIELD AND LABORATORY EXERCISES 237 



perhaps not until spring when roots are being selected for bedding 

 purposes. 



Stem-rot is often a serious disease of the plants. This causes 

 the plants to die, beginning near the surface of the ground. As 

 the disease works itself along the stems it may cause the death of 

 the plant and also a rotting of the potatoes. The disease is very 

 injurious and much damage is caused in any field where it becomes 

 well established. 



The best remedy for both of these diseases is rotation of crops. 

 When a disease has been found to exist in the soil sweet potatoes 

 should not be grown again until several other crops have intervened. 



FIELD AND LABORATORY EXERCISES 



1. Potato Growing Competition. A good home project is to grow potatoes 

 by the hill-row method as described in chapter IV. A competition may be 

 started to see who can obtain the largest yield by this method or who can 

 make the greatest increase in yield per hill. 



2. Preventing Potato Scab. Before planting time, methods of treating 

 the seed for scab should be practiced, using potatoes which are evidently af- 

 fected with the disease. Let some be planted without the treatment and some 

 with. Then compare the yields on these plots as to freedom from scab. 



3. Prepare seed potatoes in three different ways for planting: (a) Cut 

 each piece to have only two eyes, (b) Cut each piece to have four eyes, or 

 this plot may have whole potatoes if small, (c) Use whole potatoes of about 

 four ounces each. Plant each lot of potatoes separately, and at the end of the 

 season calculate the differences in yield, and compare the yields with the weight 

 of potatoes used for seed in each case. 



4. Compare the different methods of planting as used in your region. 

 Which methods are best suited for gardens? Which for large fields? 



5. The depth of planting should be tested by starting the crop at different 

 depths, as two inches, four inches and six inches. What advantages do you 

 find of one method over another? 



6. Methods of Tillage. In a field or garden where the conditions are 

 uniform, cultivate'a few rows by very deep tillage, and the remainder by fre- 

 quent shallow tillage. Compare the results and give your conclusions. 



7. Irrigation for Potatoes. Plot experiments may be conducted to show 

 the benefits of irrigation. Does the potato crop need a large supply of water? 



8. Methods of spraying as practiced by growers should be studied if pos- 

 sible during the spraying season. What size of machine would you choose 

 for a five-acre field? What size for a small home garden? 



9. Different varieties of sweet potatoes and of Irish potatoes should be 

 collected and studied in the laboratory. The advantages claimed by growers 

 for each variety may be considered in this connection. 



10. Fertilizer Tests. Grow both sweet potatoes and Irish potatoes in 

 plots, using different fertilizers in each case. The value of different fertilizers 

 for ea,qh kind of potatoes may thus be learned. 



11. Starting Sweet Potato Plants. Make a bed for starting sweet potato 

 plants. Care for it by the best methods until the plants are grown, pulled and 

 set in the field. Study among growers the different methods of setting plants, 

 and the different methods of preparing the ground for the plants. Give argu- 

 ments for the different degrees of enriching and explain the suitability of these 

 different degrees to different soils. 



