THE MONTHLY BULLETIN. 421 



Intercalary Crops. — While the trees are young, intercalary crops 

 may be grown to assist in bearing the expense of caretaking, as well as 

 to pay interest on the investment. In most instances beans will prove a 

 satisfactory revenue crop. In places exposed to high winds during the 

 summer time it may be Avell to grow one of the non-saccharine sorghums 

 or some other crop that grow-s to considerable height, as such crops will 

 serve as effective windbreaks, thus protecting the young trees as well as 

 giving some return for the extra investment necessary in the planting 

 and care of the crop. In no case is it advisable to interplant with 

 another variety of trees, as the extra income seldom pays for the addi- 



FiG. 90. — The PentUilina olive. (State 

 Hort. Com.) 



tional cost of the planting and care of the trees. On level ground 

 alfalfa may be interplanted to advantage, provided sufficient space is 

 left for the separate cultivation of the young trees. 



INSECTS AND DISEASES. 



The olive tree is fairly free from any insect enemies. The only insect 

 of any serious importance is the black scale. This pest becomes most 

 serious along the coast. The olive twig borer does some injury to young 

 trees, causing the breaking off of some of the small twigs. This, how- 

 ever, has never been a serious difficulty in California. Among the 

 diseases the olive knot is the only one that may be considered seriously. 

 The only complete remedy for this is to avoid infected stock. Some 

 varieties, however, as the Mission and Ascolano, seem fairly resistant to 

 this disease. Eipe rot of the fruit has in some years proven rather 

 serious. This, however, is confined for the most part to two or three 

 varieties. 



