ARIZONA 



sentative localities of southern Arizona, having the 

 greatest horticultural possibilities, the average yearly 

 rainfall is only 7 inches for the former and 3 for the 

 latter. In general, the precipitation is during two dis- 

 tinct seasons. The heaviest, or summer rains, begin 

 about the first of July and increase in frequency until 

 August, the month of greatest precipitation during the 

 year. The winter rains are at their maximum in Decem- 

 ber. With the exception of infrequent intervals during 

 the rainy season, dews are unknown and fogs are of rare 

 occurrence. On the other hand, from experiments con- 

 ducted at Tucson, the evaporation is about 78 inches per 

 year, reaching the maximum of II to nearly 13 inches 

 during the month of June. 



At Phoenix the mean temperature may range from 32.2° 

 to 66°F. in Jan. It steadily increases till July, when it may 

 range from 72° to 107°. It then steadily declines until 

 the next Jan. The corresponding ranges at Yuma are 

 42°-65° for Jan., and 77° to 106° for July. The variation 



ARIZONA 



97 



•^-^ I- 



142. Arizi 



The shaded parts show horticultural sections. 

 There is also a horticultural seetiou about Yuma. 



in temperature from day to night is frequently, in sum- 

 mer, from 25° to40°F.. while in winter it is even greater. 

 The annual range, however, is not so great as it is in the 

 northern states. 



The intense heat and dryness of the atmosphere, with 

 continuous sunshine and frequent scorching winds, not 

 only draw the moisture in wonderful rapidity from irri- 

 gated fields, but the foliae-e of cultivated plants, save 

 those with firm leaves, protected by thick epidermis, are 

 overtaxed at times, and not infrequently the leaves 

 wither and burn, even when the roots of the plants are 

 well supplied with water. In some instances the differ- 

 ence of a few days in time of irrigating makes or loses 

 the crop. At times, flooding at midday is disastrous, 

 destroying the plants as effectually as if swept by fire. 

 The temperature of water in irrigating ditches in mid- 

 summer often ranges from 85° to 92°P. 



The rivers of Arizona draw their moisture from the 

 wooded mountains, but as these mountains are snow- 

 covered only during winter and early spring, as the sum- 

 mer advances their supply gradually becomes less and 

 less until the beginning of the rainy season. Conse- 

 quently the cultivation of all crops must lead toward 

 great economy in the use of water during the months of 

 May and June. All crops sown broadcast or in narrow 

 drills are irrigated by flooding,while orchards, vineyards 



and crops grown in rows are usually irrigated by running 

 the water through furrows. In either system it is impera- 

 tive that the land be graded and thoroughly worked, in 

 order to attain the best results in the distribution of water. 

 The desert lands of Arizona, in their virgin state, are 

 seldom suited for orchards, vineyards, gardening, etc. 

 It is expedient to grow alfalfa for a few years before at- 

 tempting to produce horticultural crops. Usually the 

 virgin soil is deficient in humus and nitrogen, constitu- 

 ents which are most economically supplied by growing 

 alfalfa. Many orchards and vineyards have failed in 

 Arizona on account of being planted on virgin soil. 



Market-gardening in Arizona is largely in the hands 

 of the Chinese, who practice high culture, and keep their 

 lands in a continual succession of crops. Cabbage and 

 cauliflower must be grown as winter crops. For years 

 it was thought that corn could not be successfully grown 

 in southern Arizona. When planted in the spring, the 

 excessive heat and dryness of June renders the pollen 

 impotent, and a well-developed cob beariiig a few scat- 

 tered kernels of corn is the result. Experience has re- 

 cently taught that most excellent, well filled corn may be 

 grown, if planted in July and poUenized at the end of 

 the rainy season. 



Artificial fertilizers are seldom used in Arizona. In 

 preparing the soil for nearly all vegetables, both in ama- 

 teur and commercial methods of culture, it is thrown 

 into high ridges and the seed sown in hills or drills on 

 either side of the ridge a few inches below the summit. 

 In irrigating, the water is runbetween the ridges, so that 

 it reaches the hills or drills without covering them, and 

 is allowed to run for a greater or less length of time, de- 

 pending upon the ability of the soil to take water. In 

 many of the heavier adobe soils it is necessary, when 

 planting melon and many other seeds, to cover them with 

 sand. If the adobe soil of the field is used as a cover, it 

 bakes so hard that the germinating seeds are unable to 

 make their way to the surface. Beets, and occasionally 

 other vegetables, when planted on an extended scale, are 

 sown in drills without ridging the soil. After planting, 

 furrows are made between the rows in which to run the 

 water, it being imperative that the water be not allowed 

 to break through the furrows and flood the crop. 



In fruit-culture, the important priuciple is practically 

 the same for all fruit, it being essential to fill tlie ground 

 with water during the winter season, when the ditches 

 are running full, and by thorough tillage during spring 

 and early summer to retain the moisture, to fortify the 

 plants against the lack of water in May and June. 

 Orchards and vineyards may be flooded several times 

 during the winter, or the same or better results may be 

 obtained by making furrows at a distance of every 4 to 

 G feet throughout the orchard, and running a subsoil plow 

 in the furrows to loosen and break up the soil to consider- 

 able depth. When so prepared, the soil will take water 

 with great avidity, and if the process be repeated two or 

 three times during the winter, water required for subse- 

 quent culture will be much lessened. 



In orchards and vineyards, frequent irrigation with 

 little water is expensive and results are unsatisfac- 

 tory. The ground should be thoroughly wet through- 

 out, even between the rows, and as soon as practicable 

 after irrigating, tilled and later leveled by using a 

 fine-toothed harrow. This process will leave a mulch of 

 loose earth a few inches in thickness over the moist soil, 

 and assist greatly in retention of moisture. When neces- 

 sary to improve the condition of the soil by adding plant 

 food, it is most economically and satisfactorily accom- 

 plished by green-manuring, growing the crop during the 

 fall and winter and turning it under in the spring. 



Great variation in temperature during February and 

 March is very disastrous to successful fruit and nut cul- 

 ture in southern Arizona. Almonds begin to bloom in 

 February, and are followed in succession by apricots and 

 peaches, all of which are likely to be injured by spring 

 frosts. 



In humid regions, methods of pruning tend toward 

 thinning out the center of the tree, so that the sun may 

 reach the fruit spurs within. In Arizona fruit trees are 

 usually headed low, in order that the trunk be shaded. 

 Deciduous trees are usually cut back annually, throwing 

 the fruit spurs toward the center of the tree, that as 

 much as possible of the developing fruit be shaded by 



