564 THE MONTHLY BULLETIN. 



shall be known as California Certified Seed Potatoes. The matter of 

 inspection is in charge of the State Commissioner of Horticulture, and 

 the cost of inspection is to be borne by the grower. 



By means of this system it will be possible for any one to know 

 whether he has really good seed potatoes. It is to be hoped that many 

 erowers in the State will take up this matter of growing certified seed 

 potatoes, and that other growers who need good seed stock will take 

 advantage of this opportunity of securing stock of the highest quality. 



HOW SHALL SEED POTATOES BE HANDLED BEFORE PLANTING? 



Inasmuch as most seed potato stock is more or less afi'ected with scab 

 or Rhizoetonia, or both, it is advisable to soak the seed, as before stated, 

 in a solution of corrosive sublimate. When wooden tanks or barrels are 

 conveniently arranged for this purpose the treatment is inexpensive 

 and should "not be neglected. This treatment may be given immediately 

 before cutting the seed, or it may be given and the seed left to germ- 

 inate before planting ; but the treated potatoes should be spread out so 

 that they will dry very quickly after treatment. 



There is much confusion in the minds of potato growers regarding 

 the way seed potatoes should be handled with reference to cutting, 

 germinating, and size of seed piece. Much has also been said regarding 

 the use of small whole potatoes for seed purposes. Some cut off and 

 throw away the stem end and other cut off and throw away the bud 

 ends, while others pare the potatoes and plant the parings. Some 

 germinate the seed before planting, others prefer ungerminated seed. 

 More judgment is required to handle this problem in potato growing 

 than any other phase of the industry. In order to decide intelligently 

 how to deal with any individual case, we must understand something 

 of the structure and physiology of the potato tuber. The tuber of the 

 potato is not a root but a much swollen underground stem, made up 

 very largely of starch and water. The parent plant during its growth 

 stores up this starch in the tubers in order to carry the life of the plant 

 over the winter season and furnish material for the early stages of 

 growth of the new plants, which develop from it. The tuber repre- 

 sents the dormant stage in the life cycle of the potato plant Like most 

 plants adapted to a climate with a season for growth and a season dur- 

 ing which the plant must be dormant, the potato plant has developed 

 the tuber system for this compulsory dormant period. This dormant 

 or resting period of the tuber may be hastened or lengthened, depend- 

 ing upon the conditions in which it is placed. Under a temperature 

 of, say 33 to 38 degrees, the tubers will remain dormant for many 

 months. Or, if they are placed in a temperature of 33 degrees for a 

 few weeks and then placed in a temperature of 70 or 80 degrees, they 

 will germinate quickly. A certain period of rest, however, is necessary, 

 as every one knows who has tried to grow second-crop potatoes from 

 first-crop seed. Physiologically considered, it represents a period dur- 

 ing which there is little or no change from starch to sugar within the 

 tuber ; and this change is necessary before growth begins. When this 

 change from starch to sugar takes place it is most active at the bud end 

 of the tuber, which is the reason that the eyes at the bud end develop 



