10 CIRCULAR NO. 109, BUREAU OP PLANT INDUSTRY. 



the planting. If the crop does not grow rapidly after planting, irrigation should be 

 provided from time to time as the appearance of the crop and the condition of the soil 

 would indicate ; a dark-green or blackish color shows a lack of moisture on the part of 

 the plants, while light-green or yellowish tints indicate the presence of too much 

 moisture. The plant should be kept growing at the maximum rate from the time it 

 appears above the ground until it has completed its season's work, and cultivation 

 supplemented by irrigation must be relied upon to keep the plant working. 



METHOD OF IRRIGATION. 



The water for irrigating potatoes is best applied in every other furrow, the furrows 

 being narrow and deep and the water so applied that the ground will not be saturated 

 above the point where the tubers are formed. This will induce the formation of a 

 deep instead of a superficial root system. In order to accomplish this the rows must 

 be sufficiently wide apart to admit of throwing up broad high ridges, with narrow deep 

 furrows between, in which the water can be led in a small stream for a long period 

 rather than by means of a large stream flowing only for a short time. The successive 

 irrigations should be carried on hi alternate rows; the second irrigation should be in 

 the rows not used by the first, and the third in the rows used during the first. Culti- 

 vation should follow irrigation as quickly as the condition of the soil will permit, but 

 as soon as the tubers have made then growth, usually about September 1, water should 

 be withheld, so that the soil will dry and the crop ripen in proper condition for 

 harvesting. 



[Cir. 109] 



