22 BULLETIN 636, IT. S. DEPARTMENT OF AGRICULTURE. 



The rilling for the irrigation is done either by shovel cultivators, 

 single plows, corrugators, or homemade rillers. In irrigating the 

 mulch-crop orchards the system of flooding is used to a great extent. 

 In flooding the time is considerably reduced, for this method aims 

 to cover the whole orchard by allowing the water to follow its own 

 course. The topography of the land and type of soil will determine 

 the method of applying the water. 



Where mulch-crop orchards are rilled, a common tool used is a 

 "corrugator," consisting of two metal shovellike attachments with 

 a substantial iron frame. Six rills usually are made per tree row. 

 As a rule, the date for the first irrigation is earlier on mulch crop 

 than on the clean-cultivated orchards, the first watering usually 

 being made during the first two weeks in May and seldom later 

 than the last of this month. In a few cases men flood their orchards 

 in the fall. 



The average time for irrigating the mulch-crop orchards is 1.72 

 man-hours, with an acre cost of $0,345, or for the 5.18 irrigations 

 there is a charge of 8.94 man-hours and a cost of $1.79 per acre, or 

 $0.0053 per box for labor. 



Considering all records, irrigation costs $1.87 per acre or $0.0055 

 per box. The average annual water tax is $1.28 per acre, or $0.0038 

 per box, and the total for labor and water tax is $3.15 per acre, or 

 $0.0093 per box. 



SPRAYING. 



The spraying program of the Payette district is comparatively 

 uniform. All growers from whom records were taken make one dor- 

 mant lime-sulphur spray and one calyx arsenate-of-lead spray. They 

 average 2.09 other arsenate-of-lead sprays, making an average of 

 4.09 sprays for the season. 



All the growers except three own their own spray rigs, which gen- 

 erally are of standard make, although there are a few assembled rigs. 

 When the spray outfit is hired, the usual price is $1 per hour for man, 

 team, and outfit. The grower's average investment in the spray 

 outfit for those owning them is $360. The spray-rig engine varies 

 from 2 to 3| horsepower, the majority being 2\. The 200-gallon 

 tank is the one most commonly used. There are very few men who 

 use spray towers on their rigs, though in the older orchards spray 

 towers are an advantage. 



It is found that the life of the average spray rig is approximately 

 9^ years, and that the depreciation amounts to $37.80 annually. 

 This, added to an annual upkeep of $16 and an annual interest 

 charge of $28.80 on the original investment, makes an annual charge 

 of $82.60 per spray rig. 



Approximately 20 acres of fruit are sprayed annually by each spray 

 rig. This would then give an acre charge of $4.13 for depreciation, 



