404 Journal of Agriculture, \ktoria. [10 July, 1912. 



siliceous sandstone, this is broken down and is tlien washed from the higher 

 levels a.nd deposited on the lower slopes at the f(X>t of the hills. From 

 the nature of its source and depositioir ii: is, as would be expected, of a 

 light porous nature. As this soil was being formed, more or less vegetable 

 matter was brought down adid mixed through it, but this would be, com- 

 paratively speaking, quickly removed, more especially if the surface soil 

 be kept free from plant growth. 



Several of the orange groxes are on this type of soil, some of these were 

 planted many years ago, and as a consequence they have withdrawn a large 

 qua^ntity of the available plant food within their reach. 



Even in the area of a single plantation the deficiencies of plant food in 

 the soil \ary to a considerable extent, affecting both the growth and yield 

 of the trees. Generally speaking this is perhaps one of the most fertile 

 sources of trouble as the weakened vitality and starved condition of the 

 trees lay them open to attack from various citrus diseases. So far as I 

 could ascertaija no manure, with the exception of bone-dust, had been used 

 in the affected area. That this disease is more prevalent in those areas 

 which are of a dry porous nature and in which there is a lack of organic 

 matter is easily seen. Trees growing in a more retentive soil are in this 

 case not affected with " Exanthema," although they may be, and often 

 are, attacked by collar-rot and other diseases. All the evidence collected 

 in the field points to the lack of organic miatter a'nd an open porous sandy 

 soil bei'io- the chief factors in causing this trouble. 



Methods Suggested for the Control of the Disease. 



Such being the case methods must be adopted which will render the 

 soil more retentive of moisture and at the same time supply food for the 

 trees. Ploughing in green crops of oats, barley, rye, or wheat, which have 

 been previously manured with superphosphates would be the easiest and 

 best method to adopt. Nitrogenous manures should be used sparingly, if 

 at all, on the diseased areas, as they appear to have a deleterious effect 

 upon the trees. Discretion must be left to the growers as to the best method 

 of cultivation and crop suited to the district. 



Care shoulrl also be taken that no bud wood be taken from trees which 

 havi_ i)een affected, as they might possibly l:)e more susceptible if placed 

 under fa\orable conditions for the development of the trouble. 



The conditions favouring the development of the disease are — i. Porous 

 light deep, coarse or sandy soil, lacking organic matter, and which quickly 

 dries out after rain. 1. Continued drought followed by heavy rain. 3. 

 Large amounts of nitrogenous manures. 



THE OLIVE. 



Z. MacdoiialiL Horticulturist, Doohic Agricultural College. 

 (Continued from page 217.) 



Pests. 



The Olive in the older European countries is subject to the attack of 

 a number of enemies; fortunately, however, it is endowed with a constitu- 

 tion specially fitted for the resistance of such attacks, otherwise it would 

 not to-day be in its proud position in the forefront of economic trees. 



