32 BULLETIN 1125, U. S. DEPAKTMENT OF AGRICULTURE. 



below all the others, only passing Heluan in July and August. 

 There is a wide zone between it and the minimum curve of Mecca 

 from flowering time to midsummer, falling below it by 7° and 8° F. 

 even when the Tempe maximum passes that of Mecca, as it does in 

 May and June. Heluan, with its moderate mean maximum of only 

 81.5° F., against 86.7° F. for Mecca and 85.7° F. for Tempe, has as 

 a compensation a mean minimum for the year 8° higher than that of 

 Tempe, 14° higher for the month of October, and nearly 17° higher 

 for November. 



Added to the cold nights, the Tempe garden has another handi- 

 cap. The water table is at all times within 3 to 4 feet of the surface, 

 so that the palm roots are in a constantly saturated subsoil, and no 

 irrigation has been needed since 1907, when the present canal system 

 of the valley was inaugurated. The sinking of the surplus water 

 from irrigation at higher levels has created an underflow which 

 has waterlogged many acres of land in the vicinity of this garden. 

 Surface evaporation brings up so much alkali, chiefly sodium 

 chlorid, that scarcely any weeds grow in the garden, a condition 

 detrimental to fruit ripening. While the night temperatures are 

 generally low in the Salt River Valley, it is believed that in localities 

 having a warm sandy loam with good drainage and relatively free 

 from alkali the Saidy date might ripen to a point where it would 

 process into a fine product, with sufficient sugar concentration to make 

 it keep without fermentation.^^ 



RESISTANCE OF THE SAIDY DATE TO HUMIDITY AND DEW-POINT 



CONDITIONS. 



A further comparison between the Saidy date and the Deglet 

 Noor lies in its relative resistance to atmospheric humidity. In 

 Deglet Noor plantations at the Tempe date garden and at Heber, 

 Calif., when cool nights have developed a dew point during the 

 latter part of August or early September, the fully grown but only 

 partly matured fruits have developed spots of brown-rot, of some 

 undetermined species, especially around the stalk, and dropped from 

 the trees in large quantities. With a change to drier air this would 

 sometimes cease at Heber and the rest of the crop mature. 



The Saidy trees at the Tempe garden have not been known to 

 suffer from these dew-point conditions. 



In Gizeh Province the relative humidity is much higher than at 

 either Tempe or Mecca. At Gizeh the average percentage is: 

 August, 68; September, 72; October, 75. There is present on the 

 leaves of the date palm growing in warm, humid stations, such as 

 the lower coast regions of California and the southern Gulf Coast, 

 a fungus of the group of smut fungi, Graphiola phoenicis. This, 

 with other species, may be found on palms cultivated in greenhouses 

 and conservatories, but seldom, if ever, occurs in the drier, more 

 desertlike stations where the date palm usually is grown. It is a 

 valuable humidity index, though seldom a serious detriment to date- 

 palm growth. 



1" This present year, 1922, under conditions of an exceptionally dry summer in the 

 Salt River Valley, some dates on the Saidy trees in the Tempe garden are ripening, thus 

 increasing the probability that this variety may be matured in the drier and warmer 

 localities of that section. 



