336 MONTHLY BULLETIN. 



mulch directly under the trees, but cultivating and raising summer 

 cover crops between the rows. One of the most interesting cover crops 

 seen was the pigeon pea (Cajamis indicus), which grows very tall and 

 woody. This crop appeared to give excellent results when grown 

 between the rows of young trees so as to both shade them and serve as 

 a partial windbreak. 



Fertilization. 



In Cuba as in Florida there is a great diversity of fertilizer practice. 

 A considerable amount of commercial fertilizer was being used on the 

 poorer soils with apparently excellent results. 



The effect of the addition of organic nitrogenous fertilizer at Her- 

 radura on a clay loam soil was also of much interest. It is well known 

 that in Florida on most citrus soils the addition of large quantities of 

 such fertilizer is likely to bring on Exanthema or dieback. On this 

 place there were certain grapefruit trees where chickens had been roost- 

 ing and large amounts of droppings had gone on to the soil. These 

 trees, contrary to what one would expect from Florida experience, were 

 much healthier and more vigorous than those not receiving these 

 droppings, and not the slightest indication of Exanthema was apparent. 

 The fruit w^as more abundant and brighter than that in the other part 

 of the orchard. Another set of trees had been growing inside of a pen 

 where hogs had been kept for some time. Some months had elapsed 

 since the pen had been discontinued. The trees showed a distinct 

 evidence of benefit also from this treatment. On most soils in Florida, 

 either the constant droppings from the chickens or the hog penning 

 would have been almost certain to have brought on Exanthema and 

 caused a large amount of injury to the trees. In this connection, it 

 may be of interest to note that not a single case of Exanthema (dieback) 

 was seen on the Island of Cuba, and Professor F. S. Earle tells me he 

 has never seen it there. Only one case of Exanthema was seen on the 

 Isle of Pines and that was where the subsoil was stiff clay and where 

 the drainage was very poor. In several places in Cuba where the 

 drainage was also poor and where one would expect to find Exanthema, 



none could be found. 



SUMMARY. 



To sum up briefly some of the principal differences between citrus 

 conditions and practices in Florida and California : 



1. Florida's citrus regions lie between about 25 to 30 degrees north 

 latitude with 40 to 60 inches of rainfall during late spring, summer 

 and early fall. California's citrus regions lie between 32^ and 39^ 

 degrees with 10 to 20 inches of rainfall during late fall, winter and early 

 spring. 



2. Florida, therefore, has a moist, humid atmosphere during most 

 of the growing season, making it possible to grow citrus fruits without 

 irrigation, while California, during this same season, has a dry atmos- 

 phere without rains, making it necessary to practice irrigation. 



3. In Florida, cultivation is usually discontinued throughout the 

 rainy season of summer, and in California is usually kept up during 

 the summer because of the necessity of frequent irrigations and the 

 conservation of moisture in the soil. 



