144 DISEASES OF TROPICAL PLANTS 



CH. 



GUAVA 



Fruit Rot. This disease is due to Glomerella psidii 

 (G-. Del.) Sheldon, and is more or less common in the 

 West Indies, Florida, and California. The disease first 

 appears as brown decaying spots which are finally 

 covered with mass of salmon-coloured spores. The 

 fruit gradually rots, becomes wrinkled and shrunken. 



OLIVE l 



The olive tree grows well within the tropics, but 

 appears to be productive only in rather dry countries. 

 It has attained its principal commercial importance in 

 regions having a marked winter season. About 16 F. 

 is its limit of endurance of cold. Within its proper 

 climate it is a very rugged and resistant tree, enduring 

 extremes of heat, drought, soil poverty, and neglect. It 

 will not bear abundant crops, however, without fairly 

 good soil, good cultivation, regular pruning, and, 

 except in the most favoured spots, some irrigation. 



Olive Knot (Bacterium savastanoi, E. F. Smith). 

 Olive knot is also known as tuberculosis of the olive, 

 rogna in Italy, gale in France, and by several other 

 names. It probably occurs throughout the Mediter- 

 ranean olive-growing districts, and has been observed 

 at several points in California. It is said to be of little 

 importance in the more extremely hot and arid regions 

 where olives are grown. 



So far as is known, no variety is immune. In 

 California the San Diego Mission is considered to be 

 somewhat resistant. This and the Manzanillo are 

 among the most popular for making ripe pickles, which 

 are regarded as the most profitable product of the olive 

 in the United States. Some of the smaller varieties, 

 which are used almost exclusively for making olive oil, 

 are very susceptible. The Nevadillo appears to be one 

 of the worst in this respect. 



1 Prepared by Prof. Wm. T. Home of the University of California. 



