THE AVOCADO 27 



ably not great either in California or Florida, and has been 

 over-estimated in the past. In Florida, the West Indian race 

 usually blooms late enough to escape the coldest weather, while 

 in California the Mexican race, though it blooms in winter, is 

 sufficiently hardy to withstand ordinary frosts, and the Guate- 

 malan race does not bloom until April or May. The latter 

 race is, therefore, the safest in this respect. 



In California, avocado culture is not dependent on rainfall, 

 since irrigation is commonly practiced. In Florida, on the 

 other hand, very few crops are irrigated, and up to the present 

 it has been the general custom not to irrigate avocado trees, / 

 except during the first two or three summers. It is coming 

 to be recognized, however, that a wet spring is followed 

 by a good avocado crop and a dry one by a poor crop (a 

 condition exactly reversed with the mango). As a result of 

 this observation, irrigation is beginning to be practiced in 

 southern Florida, especially in seasons when the rainfall is 

 below normal. 



The necessary soil-moisture can be supplied easily and 

 satisfactorily, but the relative humidity of the atmosphere 

 cannot be altered artificially; hence in regions wfiere the 

 humidity is exceedingly low the avocado suffers in the dry 

 portion of the year. In Florida no attention need be paid to 

 this subject, since the humidity closely approaches that of the 

 West Indies and other regions where the avocado is at home. 

 Humidity may prove, however, to be the limiting factor in 

 parts of California. Tests in the Imperial and Coachella 

 Valleys indicate that the trees are seriously injured by the dry- 

 ness of the atmosphere. Experience shows that the Mexican - 

 race is less susceptible than the West Indian. None of the 

 varieties so far tested, however, has proved to be so resistant 

 to atmospheric dryness as the orange or grapefruit. Shading 

 may help to limit the injury from this source. It has been 

 found very beneficial in 4 the coastal belt of California, where 



