THE MONTHLY BULLETIN. 197 



THE NEXT STEP IN THE SEED POTATO PROBLEM. 



By W. "V. Shear, Assistant Horticulturist, United States Department of Agriculture. 



In previous articles the important features of good seed potato pro- 

 duciion have been considered, viz. : that of growing disease free seed 

 and, at the same time, productive seed or seed that has been so handled 

 that it will produce large crops. The people, however, who are inter- 

 ested in growing such seed stock, and who are willing to devote th'3 

 proper attention to the production of such seed potatoes, are naturally 

 anxious to know something more tlian how to produce them. If they 

 grow them in larger quantities than are sufficient for their own needs 

 the following year, they want to know how they can dispose of them. 

 On the other hand, the potato growers in the delta of California and 

 other sections as well, are inquiring where such good seed can be 

 obtained. How can the producer of good seed potatoes find a market 

 for his stock and how can the consumer be sure of getting such stock 

 when he bu.ys seed potatoes? 



In order to meet this difficulty several states have put into practice 

 what is called seed potato inspection and certification. The West 

 Coast Potato Association now proposes to adopt some such method for 

 the certification of seed potatoes in California. Briefly, the plan is as 

 follows : All parties desiring to grow certified seed potatoes shall adopt 

 the following methods for their production. The seed stock shall be 

 treated with corrosive sublimate by soaking it for one and one-half 

 hours in a solution made by dissolving four ounces of bichloride of 

 mercury in thirty gallons of water. As this substance is difficult to 

 dissolve in cold water, it is advisable to add an ounce of sal ammoniac 

 to the corrosive sublimate and dissolve this in a small amount of hot 

 water before adding to the thirty gallons of cold water. 



The seed shall be planted on land Avhich has not produced potatoes 

 for at least four years preceding the present crop. Great care should 

 be used to secure seed stock free from mixture with other varieties. 

 When the plants are in full })loom the field shall be inspected by a 

 competent person and diseased and weak hills removed, as well as 

 mixtures of varieties. If more than 250 mixed hills or 500 weak hills are 

 found per acre, the field will be disqualified for certification. A second 

 inspection shall be made before digging, preferably just before the 

 flants are ripened, and an estimate made of the number of low yielding 

 hills and also of the amount of disease present. A third inspection 

 shall be made after the potatoes are harvested and sorted. The tubers 

 shall run not under two ounces nor over sixteen ounces in weight, 

 shall be practically free from mixture with other varieties, shall not 

 be knobby or badly damaged, shall not contain over 6 per cent of wilt 

 infection, and shall be practically free from scab and Rhizoctonia. A 

 small amount of the two latter diseases may be admitted. 



All seed stock coming up to these specifications shall be certified as 

 good seed potatoes, and the owner will be given a certificate to this effect. 

 Inasmuch as there is likely to be but a small amount of seed stock 

 which will measure up to the above specifications the coming year, 

 it is proposed that the inspector give growers of seed potatoes, where the 

 stock falls somewhat short of the above requirements, a certificate 



