54 THE DATE PALM. 



During- July and August more than three times as much rain falls at 

 Phoenix as at Biskra, although the annual rainfull is nearly one-third 

 greater at the latter station. 



Unfortunately records are not available for the Salton Basin, but 

 the very low rainfall in spring, summer, and autumn, and the exces- 

 sively high temperatures which prevail there render it certain that the 

 humidity is very slight probably somewhat lower than at Gharclai'a. 

 There is, however, as in Arizona, a well-defined rainy reason in July 

 and August, which tends to raise the humidity for those months. 



RAINY WEATHER DISASTROUS TO THE FLOWERS AND RIPENING FRUITS 



OF THE DATE PALM. 



Besides its indirect harmful action in decreasing the amount of sun- 

 shine and heat and in increasing the amount of humidity in the air, 

 cloudy or rainy weather is directly injurious to the date in preventing 

 the fertilization of the flowers in spring, and also in bringing about 

 the decay or dropping of the fruit when it is ripening in autumn. 

 When the flowers are being pollinated a spell of wet, cloudy weather, 

 by spoiling the pollen may hinder the setting of the fruit, though 

 usually the harm can be remedied by repollinating with a fresh spray 

 of male flowers when the weather becomes dry. In autumn the effects 

 of rainy, humid weather are much more disastrous and may entail the 

 loss of the entire crop by causing the dates to ferment and spoil just 

 when they are ripening. No misfortune is more feared by the date 

 growers in the Sahara than wet weather at this time. 



Most varieties of date palms flower in April and May in Arizona, as 

 in the Algerian Sahara, and the best sorts begin to ripen in October 

 and November. The following table shows the amount of rain for the 

 months of April and Ma} r , in spring, and October and November, in 

 autumn, for a number of points in the Southwest, and also for Biskra 

 and Ayata in the Sahara. 



