32 DATEGROWING 



United States left the palm little damaged, although 

 oflScially recorded temperatures through which it 

 passed were 15° at Indio, Cal., 133^° at Mecca, Cal., 

 12° at Tempe, Ariz., 8° and 9° in Texas, and 53^° at 

 Tucson, Ariz. In some cases it killed off many of the 

 leaves, but the fruit came on as usual — in fact the 

 only damage to flowers was in the case of male palms, 

 which seemed in many cases to have been rendered 

 sterile by the temperature. Young palms are natur- 

 ally more tender, but they can be easily protected. 

 No such low temperatures as these have previously 

 been recorded from a date-growing country, — in 

 Baghdad, for instance, the lowest on record is 17° — 

 and that the palm withstood them successfully shows 

 that frost need hardly be taken into consideration in 

 the future, in selecting a location for palms. 



For the man who wants to go into the commercial 

 production of dates in the United States at once, the 

 facts which I have quoted will have little importance; 

 he can only be advised to confine himself to the 

 Salton Basin in California or the low-lying parts of 

 Arizona. But the investigator who wants to find how 

 far he can extend the date-growing region may get 

 encouragement from the experiments of other coun- 

 tries, which show that there is at least a possibility of 

 growing eatable dates in any country where the 

 summers are hot. In deciding as to the climate for 

 dates, it has been the custom to sum up the maxima 

 of heat; but this is a misleading method, for Vinson 

 has clearly shown that the growth of the palm varies 

 not according to the heat of the day, but according to 

 the added heat of day and night: that is, the palm 

 grows best when the night temperature is nearest 

 that of the day, provided both be fairly high. There- 



