HORTICULTURE. 43 



sonthorn Tunis, in which re}j;ion the averase yeaii.v rainfall is only 9.3 in. The 

 drought-resistant variety of the olive that is grown in Tunis has been introduced 

 with a view to establishing dry-land olive culture in the United States, and it 

 is believetl that the present work will be useful not only in directing attention to 

 the type of tree and methods of culture that ai"e likely to give the best results 

 in the olive zone, ))ut also in stimulating as well the cultivation of trees in gen- 

 eral in arid and semiarid regions. 



A discussion is given of the importance of dry-land arboriculture in ancient 

 Africa, the climate, topography, and soils of the Sfax region, and the cultural 

 methods employed, including propagation, clearing the land, planting, tillage, 

 manuring, pruning, harvesting, and yields. The relation of rainfall to yields, 

 the question of labor, and the utilizati(m of the run-oft" water in olive culture 

 in otlier parts of Tunis are also discussed. Only one variety of olive, the 

 Chemlaly, a small-fruited, oil-producing variety, is extensively grown in the 

 Sfax region. It is very productive and the fruit yields an unusually high per- 

 centage of oil. Wide ])lanting and thorough cultivation are the most important 

 principles of olive culture at Sfax, the trees being planted G5 to SO ft. apart in 

 each direction. There appears to be a relation between the yield of the olive 

 and the rainfall of the previous year, but none between the yield and the rain- 

 fall of the year in which tlie crop is made. 



The decay of oranges while in transit from California, G. H. Powell et al. 

 iU. S. Dcpt. Agr., Bur. Plant Indus. Bui. J23, pp. 79, pis. 9, figs. 26).— This is 

 the lirst comprehensive report on the investigations which are being conducted 

 by tlie Bureau of Plant Industry of this Department in cooperation with the 

 California orange growers relative to the causes and control of the decay in 

 citrus fruits while in transit to eastern markets. The investigations in general 

 liave been conducted under commercial conditions with a view to rendering 

 the data secured of practical value in the various pliases of the industry. In 

 the experimental investigations it was souglit to determine the comparative 

 susceirtibility to decay of oranges handled in difterent ways for shipment, in- 

 cluding holding them in the packing houses in California for about 2 weeks, 

 forwarding to New Yorlv at short intervals after packing under ventilation, 

 icing, and precooling, and handling in different ways and shipping under difter- 

 ent conditions when stored in a common storage room in eastern markets. Tech- 

 nical investigations in refrigeration were also conducted, including the develop- 

 ment and testing of various methods of cooling the oranges for shipment and 

 the determination of changes in tlie temperatures of cars when shipped under 

 difterent methods. For a proper understanding of the work under discussion, 

 a general account is given of the California citrus fruit business relative to 

 its extent, location, cultural conditions, and methods of picking, packing, and 

 shipping. 



The preliminary survey of the winter of 1003-4 showed that the decay varied 

 in extent in difterent regions and in difterent packing houses in the same region 

 and that it usually increased in severity as the season advanced. As has been 

 l)revious]y noted in a preliminai-y account of the work (E. S. R., 17, p. 663), it 

 was found that the decay was caused by a blue mold fungus, which enters the 

 orange through mechanical abrasions in the skin. A systematic series of ob- 

 servations and inspections was started in 1905 to determine the amount and 

 severity of mechanical injuries of oranges when delivered to the jiacking 

 houses and the relations of the methods of handling the fruit to these injuries, 

 and a variation commonly miming from 1 to .50 per cent was found in the 

 amount of injury in the fruit of different pickers, growers, and i»acking houses. 

 Largely as a result of this investigation the relation between mechanical injury 

 to the orange and the chance of decay during shipment is now generally under- 



