L3 



the practice of packing is now making headway. Only the common 

 sorts are packed in barrels, the better kinds being packed in specially 

 constructed crates, steadily assuming a smaller size so thai all the 

 fruits contained can be inspected at a glance by I li<- purchaser in 

 London, Liverpool, or Manchester. It is by following in this direction 

 that a better and more reliable market can be obtained and kept. — 

 From Journal Jamaica Agricultural Society. 



.). N. 



584. COLLAR ROT, OR MAL DI GOMMA, OF 



CITRUS TREES- 



Tins is. unfortunately, one of the best known of citrus diseases, 

 for it occurs wherever oranges or lemons are grown, often causing 

 Serious loss. The first mention of it was in connection with the 

 orange-groves of the Azores, where it seems to have originated, and 

 was noticed as early as 1832. Like many other diseases, it attained 

 its maximum, then began to decline, and about forty years afterwards 

 its force was spent, and it ceased to be regarded as serious. 



Meanwhile it spread to Southern Europe, and afterwards appeared 

 in Florida and California. It has now obtained a footing in Australia, 

 and annually causes considerable loss. From the very nature of the 

 disease, which attacks young and old trees alike, and may sometimes 

 •• ringbark" them in the course of a few months, entire groves are 

 either destroyed or rendered almost worthless. It is generally spoken 

 of as a mysterious disease, but the discovery of the parasitic fungus 

 causing it has brought it within the domain of rational treatment. 



Symptoms. — The disease has often made considerable progress 

 before the grower is aware of its presence, because it begins so low 

 down that it is overlooked. One of the first indications is the exuda- 

 tion of drops of gum at the neck of the tree, and this is so constant, 

 that where there is no gumming some other disease is at work. It 

 would appear that the fungus parasite excites the flow of gum for its 

 own convenience, for I found numerous conidia actively germinating in 

 it. and producing filaments at either end or laterally. The gumming 

 may occur at one or more spots, and the bark at the same time becomes 

 discoloured. The browning of the bark is the sign of rotting, which 

 gives rise to a decidedly disagreeable odour, and the bark gradually 

 rots away and is thrown off. If the tree is able to renew the bark and 

 arrest the progress of the disease, further mischief is prevented, but 

 usually the disease runs the following course : — The cambium layer, 

 which lies between the wood and bark, is the formative portion of the 

 stem, giving rise to new wood on the inside and fresh bark on the out- 

 side, and containing the necessary elements for building up. The 

 object of the parasite seems to be to reach this treasure-house, and 

 accordingly the decay reaches the cambium layer, and even extends to 

 the wood. When this happens there is no possibility of the renewal 

 of the bark, and that portion is dead. Then the disease spreads 

 further in all directions, principally around the base of the stem and 

 down to the main roots. Gradually the diseased area is extended, the 

 ree is completely girdled, and death ensues. While this is taking 



