18 CIRCULAR XO. 113, BUREAU OF PUAXT INDUSTRY. 



water surface during the summer months is about 10 inches per 

 month exphiins the necessity for irrigating oftener than in the less 

 arid regions. 



Provision should be made to drain away the water that runs out 

 at the ends of the furrows, so that it can not back up over the hills. 

 The water must be kept in the furrows below the tubers. 



Irrigating in alternate furrows is not practiced here and probably 

 is not ad^-isable. Great care must be exercised in keeping the growth 

 of the potatoes continuous and unchecked or the result will be knotty, 

 badly shaped tubers. 



Cultivating. — It is a distinct advantage to cultivate after each 

 irrigation until the ^dnes interfere. The tool most commonly used 

 is the winged-shovel plow. This keeps the furrow open and gives 

 the land only partial cultivation. A spike-tooth cultivator with a 

 large rear shovel to open the furrows gives better results. 



Diseases. — The most serious disease affecting the potato is the 

 potato scab {Oospora scahies). Xo seed affected with this disease 

 should be planted without thorough disinfection, but it is preferable 

 to use seed that has never been infected. Potatoes may be disin- 

 fected by immersing the sacks containing them in a formalin solu- 

 tion for two hours. The solution is made by mixing 1 pint of formalin 

 with 30 gallons of water. 



Another disease that results in considerable damage is that caused 

 by the potato eelworm. Seed potatoes containing the eelworm 

 should never be planted, as they not only injure the crop but per- 

 manently infest the soil.^ 



ONIONS. 



A large acreage of onions was planted on the Truckee-Carson 

 Project in 1912, the plantings varying in size from 1 to 7 acres. 

 One of the best fields was surveyed and found to have yielded slightly 

 over 20 tons per acre. 



Cost of production. — An estimate of the cost of growing onions on 



this same field was also made and is given lierewith, figured on a 



1-acre basis. - 



Cost of seed S8. 00 



3^ days, hauling maniu'e 7. 90 



3J days, planting and ui'igating 7. 90 



I day, repah'ing ditches 1. 70 



7 days, fii'st cultivating and weeding 15. 75 



6 days, second cultivating and weeding 13. 50 



30 days, pulling, topping, and hauling 67. 50 



Total cost 122.25 



1 For more complete information in regard to potato culture, write for the following bulletins and circulars, 

 which may be secured by sending requests to the Secretary of Agriculture, Washington, D. C: Farmers' 

 Bulletins 407, The potato as a truck crop, and 386, Potato culture on irrigated farms of the West; Bureau 

 of Plant Industry Circulars 90, Suggestions to potato growers on irrigated lands, and 91, The nematode 

 gallworm on potatoes and other crop plants in Nevada. 



- All man labor is charged at the rate of S2.25 per day. 

 [Cir. 113] 



