122 



THE OLIVE 



ditions having no part in its decline. The propagation of this dis- 

 ease through the creeper, can be effected by the contact of healthy 

 with infected plants. Infection through the spores commences in 

 the trunk, and is transmissible by the wind. 



Where this malady is suspected, if it exists, an examination will 

 show the fungoid growth of the Agaricus melleus. The only rad- 

 ical treatment for this parasite is to uproot the infected trees at 

 once, and burn at least the affected parts. The extirpation of the 

 mushroom will prevent propagation by spores. Other trees should 

 not be planted immediately in ground from which diseased ones 

 have been removed. 



FUMAGO OLELE, BLACK SMUT OR RUST. 



{See Plate XV.) 



This is an epiphyte fungus which attacks the branches and foliage 

 of the olive more especialty on the under parts. (Fig. 1.) It consists 

 of black sooty blotches which form an incrustation more or less 

 dense, which is smooth on the adhering side and scaly on the outer 

 side. The black powder, greatly magnified, is seen in (Fig. 2.) 

 The trees attacked by this black smut, languish as it impedes the 

 exhalation of the leaves. It manifests itself mostly on plants that 

 have not sufficient light, or which are situated in soil that is poor, 

 or low and humid. Sometimes it follows immediately the invasion 

 of the scale which have enfeebled the branches or where the Honey 

 dew prevails. These are conditions favorable to this fungus. 



Some entomologists claim that the scale is the cause of this fungus. 

 This is a question in olive culture that has been widely discussed 

 and has occupied the attention of European experts for the last 

 hundred years with the result that it may now be stated positively 

 that this fungus can be propagated without the aid of the scale insect. 

 The black scale and the black fungus are two separate and distinct 

 pests to which the olive tree is subject and though they are often 

 seen together, have origins entirely distinct. 



