Page:The Olive Its Culture in Theory and Practice.djvu/150

122 having no part in its decline. The propagation of this disease 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 radical 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 OLEÆ, 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.