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tainty the presence of the malady. Trees affected with the disease may 

 grow for years and show only one of these characters ; in other cases 

 ftU the symptoms may be present, but to a very slight extent, so that 

 careful search must be made to find them. As the disease progresses, 

 the brown staining of the fruit and twigs becomes more abundant 

 and the dying back of the twigs occurs all over the tree ; eruptions form 

 on the young and old twigs ; nodal swellings, due to the gum pockets, 

 become very abundant ; and the tree assumes the dense foliage and re- 

 gular outline described above. In this stage of the disease many fruits 

 Bet, but they usually turn yellow, become stained, split, and fall before 

 maturity, only a few, if any, reaching full size. Soon the gum erup- 

 tions extend to the old limbs and these die back. The rank new growth 

 becomes limited to the centre of the tree ; here branches grow luxu- 

 riantly for a time, only to become stained and die back later. The tree 

 then assumes the ragged appearance described above. In this stage 

 no fruits set, and, indeed, the tree has become so sick that no flowers 

 are formed. This disease is not accompanied by profuse blooming, as 

 is the case in blight ; on the contrary, the tendenc}' is to produce very 

 little bloom. If the disease is allowed to continue unchecked the trees 

 will ultimately cease to grow and finally die. 



Cause. — The cause of the die-back is not yet thoroughly understood. 

 For several years experiments have been under way to determine 

 whether various fertilisers may not produce the malady. Experiments 

 have also been conducted in the laboratory with water cultures. In 

 these experiments various forms of pure chemical manures were 

 employed, the amounts used being under absolute control. From the 

 results of these experiments and from extensive field observations in 

 many parts of the State it seems highly probable that the disease is 

 caused by malnutrition. In most cases it is probably induced by exces- 

 sive use of organic nitrogenous fertilisers. As before stated, trees near 

 stables, chicken houses, privies, etc., are very commonly affected by the 

 disease. Heavy applications of cotton-seed meal, dried blood, or other 

 highly nitrogenous orgarjic fertilisers are frequently followed by the 

 appearance of the trouble. Groves fertilised continuously with organic 

 fertilisers rich in nitrogen are usually more or less affected with the 

 malady, depending upon the quantity of fertiliser used. Whether the 

 chemical manures, such as nitrate of soda or sulphate of ammonia, when 

 used in excessive quantities, will finally produce the disease, is yet ques- 

 tionable, but all evidence indicates that they wiU not. In several 

 experiments the excessive quantities of chemical manures used killed 

 the trees outright, although no signs of the disease appeared. 



A form of the disease known as soil die-back is very common and is 

 very evidently independent of the action of any fertiliser. Certain 

 fields of limited area, which are low and poorly drained or underlaid 

 with hardpan'* (a ferruginous sandstone), seem predisposed to pro- 

 duce the disease. Trees set out on such soils never develop normally, 

 but contract die-back in its worst form. These frequently remain for 

 years in a stunted condition, each year's growth as formed dying back. 

 Such trees finally die if allowed to remain untreated. Often consider- 

 able loss is incurred by planting and fertilising groves on the die- 

 back soils. The symptoms of die-back are the same whether due ta 



