INJURIES BY INSECTS DISTINGUISHED FROM ORGANIC DISEASE. 3 



between the fingers, coming oft" with the scales, and showing no close 

 attachment to the surface of the leaf. 



The fungus feeds upon the substance of the dead or vacated scales, 

 and is not directly parasitic upon the plant. It is extremely injurious, 

 however, by reason of the closely-felted coating which is formed, causing 

 the bark to harden and the tree to become "hidebound." 



Foot-rot. — This disease appears only upon sweet seedling orange 

 trees, most frequently between the ages of nine and twelve years, and 

 ofteu bears a deceptive resemblance to the work of insects. It takes the 

 form of cancerous sores, which destroy the cambium layer of the bark. 

 The sores are confined, except in rare instances, to the foot or collar 

 of the tree, and begin as little cavities filled with fermenting sap and 

 having an oflensive, soar odor. These cavities extend their boundaries, 

 the outer bark dries and cracks, allowing the sap to exude and run 

 down ui)on the outside. Sometimes winding channels are formed in the 

 inner bark by the burrowing of the pus, and when these are laid bare 

 by the knife the resemblance to the track of a " Sawyer," or coleopter- 

 ous borer, is very striking. When the sores become extensive the dead 

 outer bark above them sloughs away, exposing the dry wood beneath. 

 At this stage the disease is liable to be mistaken for the work of "■ Wood- 

 lice" or White-ants (Termites), which will, moreover, very likely have 

 made their appearance. The characteristic mark by which the galleries 

 of termites may most readily be distinguished from sores of footrot con- 

 sists of a lining of comminuted wood with which these insects always 

 smooth the walls of their tunnels and chambers. If this is wanting in 

 any of the wounds, even though termites be seen in the immediate vi- 

 cinity, they cannot be the authors of the mischief. 



Foot-rot usually ends by girdling and killing the tree. Like cancer 

 in animals, it is sometimes successfully treated by a free use of the 

 knife, although this frequently serves only to aggravate the ditiiculty 

 and increase the area of the disease. 



Antiseptic treatment with lotions and poultices containing carbolic 

 acid might prove beneficial, but seems never to have been tried. A 

 remedy that has been found practicable, if taken in time, is to plant at 

 the foot of the diseased tree young stocks of the Sour v range, which is 

 never aflected by the disease, and as soon as they have established 

 themselves, tograftthem into the trunk two feetormoreabovethe ground. 

 These supplementary stocks will in time replace the original roots and 

 form a new crown, while supporting and preserving the life of"the tree. 



Many insects, attracted by the fermenting sap, resort to these sores. 

 They are all scavengers, feeding only u[K)u the lifeless bark and sap, 

 or else innocuous and predatory species, such as lurk in dark, cool 

 places everywhere. 



Smut. — A deposit resembling soot is found upon the leaves and bark 

 of trees which have been infested with certain kinds of bark-lice. It 

 is not confined to the Orange, but is found upon the Oleander, the Olive, 



