THE IRKIGA.TIOS AVE 3JJ 



The mean minimum annual temperature for the same places is as 

 follows: El Golea, 56 degrees F. : Phoenix, 50 degrees F.: Gardaia. 



Degrees F.; Yurna, 5^-3 degrees F.; Laghouat, 49 degrees F. ; 

 Tucson. 52.9 degrees F. The mean annual temperature at Cairo, 

 Egypt is 71 degrees F. : at Yuma. Arizona 72.6 degrees F.. at Phoenix, 

 Arizona 69 degrees F. 



Dates are successfully grown in regions where the winter tem- 

 perature falls as low as 20 degrees F., and their growth is still 

 possible where the temperature occasionally falls 14 to 16 degrees 

 F. below freezing. They are grown in regions where the orange is 

 unable to exist for a single winter. 



On the tableland of Baluchistan, and a few other regions of the 

 Old World, dates are profitably grown where the sum total of slimmer 

 heat is far less than in favorable localities in Southern Arizona. 



Experience has taught that the Northern limit of successful date 

 culture, so far as dependent on temperature, is marked by the lower- 

 ing of the average temperature for the year below 69 degrees F. 

 This, however, is only an approximate guide, as it is not so much the 

 warmth of the entire year or the absence of winter's cold that the 

 date palm requires, as it is a high temperature for eight or nine 

 months of the year, during which the tree makes its growth, blossoms 

 and ripens its fruit. A high temperature for this period is important. 



Aside from the value of the date as a desert plant its influence on 

 the cultivation of other plants is considerable. Many economic 

 plants unable to withstand the almost vertical rays of the sun, 

 receive from the crown of the palm enough shade to enable them to 

 be grown with success. 



Putting away the above evidence, proof in regard to the success- 

 ful production of dates, in Southern Arizona lies in the actual 

 growing of them. 



The date palm has been grown in portions of the United States 

 and adjacent Mexico for many years. Within the borders of the 

 United States, however, until recent years it has been planted in 

 more or less humid regions where it matured little if any fruit, 

 although in many instances the trees grew luxuriantly and to large 

 size. 



The date as a fruit producer being indigenous to a desert environ- 

 ment does not take kindly to humid regions. In the more arid 

 portions of Lower California and Sonora the early plantings have 

 been more or less successful and dates of fair quality have been grown 

 for some years. 



In the vicinity of Yuma date seeds planted in 1*75 have grown to 

 trees which are now from thirty to fifty feet in height and which have 

 fruited without interruption for the past nineteen years. These trees 

 produce yearly from six to nineteen bunches of fruit, the bunches 

 weighing from -fifteen to forty pounds. 



