the; potato. 4.45 



untreated vines are dead, thereby developing larger potatoes and con- 

 sequently a greater yield. 



At the experimental station in Rhode Island two rows in the center of 

 a field were not treated with the Bordeaux mixture and the leaves 

 blighted and dried up soon after August ist., leaving only the bare, 

 dead stems, while the plants in the rows that were treated remained 

 with their leaves green and healthy. When the potatoes were dug in 

 the fall the untreated rows j'ielded marketable tubers at the rate of 

 thirty-three barrels per acre, while the others averaged ninety-seven 

 barrels per acre. 



The first application of Bordeaux mixture should be made when the 

 vines are one-third grown or earlier if the disease appears. If it is 

 washed off by rain repeat after two weeks. If the Colorado beetle is 

 present add half a pound of London purple or Paris green to each forty 

 gallons of Bordeaux mixture. 



Potato Scab. Nearly every farmer is more or less familiar with 

 the disease of potatoes called ' 'scab. " It is scientifically named Oospora 

 scabies. Farmers have noticed that this disease is most prevalent in 

 fields that have been heavily fertilized by barnyard manure. This is 

 supposed to be caused by the stock being fed with potatoes that have 

 been affected by the scab. The spores of this disease do not seem to 

 lose their fertility during digestion and passes out into the compost to 

 be spread over the field and attack the developing tubes. It can often 

 be seen on partially developed scabby potatoes in the shape of fine white 

 threads running over the surface. Repeated experiments show that if 

 scabby potatoes are planted, scabby potatoes will be dug in the fall. 



Treatment. Dr. Roland Thatcher after many years of study and 

 experiment describes the preventive measures as follows : 



1. The seed must be freed from scabs. 



2. Land that has produced scabby potatoes must not be planted with 

 potatoes in less than three years. 



3. Land planted with potatoes must not be fertilized with manure from 

 stock that have been fed scabby potatoes or beets. 



4. Scabby potatoes should not be fed stock raw, but should always be 

 thoroughly cooked, even if the land on which the manure is to be placed 

 is not to be immediately planted with potatoes. 



5. Any other fertilizer is to be preferred to barnyard manure, even if 

 free from droppings of animals fed on diseased potatoes. 



6. If the potatoes show evidence of "scab" dig as soon as mature, be- 



