k 



31 



grown, becomes stained by the characteristic reddish exudations 

 like that occuring on the branches, and prematurely falls. 

 Fruit which hangs on the tree till nearly ripe is large and 

 coarse and is frequently stained. It usually splits and falls 

 before thoroughly ripe. The fruit on a slightly affected tree 

 is very large and coarse, with a very thick, rough rind. Much 

 of it is rendered unsaleable by the reddish Die-back stain. 

 It is very prone to split and fall before mature. Frenching, or 

 variegation of the foliage, frequently accompanies die-back and 

 seems to be a sympton of the disease. The very dark green 

 colouration which some growers believe to be an indication of a 

 healthy grove, may, on the contrary, denote a condition verging 

 on die-back. A lighter green would probably indicate better 

 general health. 



Die-back a disease of indigestion. 



Die-back appears to be a form of indigestion, due to an over- 

 fed condition of the plant. It occurs apparently wherever 

 excessive quantities of nitrogenous manures from organic 

 sources are applied or become available to the plant. Trees 

 near closets or barns or in barnyards almost invariably have 

 die-back. When chickens roost on a tree for any length of time, 

 ■ so that the dropping fall on the soil beneath, the disease 

 usually results. Many cases are known to the writer where it 

 has apparently been caused by excessive applications of cotton 

 seed meal, blood and bone, barn manure, etc. Indeed all 

 organic fertilisers in excessive quantities appear to give rise to 

 it. If organic fertilisers are used they must therefore be ap- 

 plied with considerable caution to avoid an excess. No safe 

 rule can be given as to the amount of manure that can be used 

 with safety ; this depends upon the size and condition of the 

 tree, previous treatment, and soil conditions. 



Whether the chemical manures, nitrate of soda and sulphate 

 of ammonia, will produce the disease if used in excessive 

 quantities, is questionable. We have not been able to learn of 

 any instance where this has ocurred. Several cases are known 

 where nitrate of soda was used of sufficient strength to cause 

 the leaves to fall without producing any sign of this disease. 

 Frequently the method of cultivation has considerable to do in 

 causing die-back, excessive cultivation appearing to aggravate 

 it very greatly. 



Mal-di-gomma. 



The much dreaded disease of foot rot, or mal-di-gomma, is 

 probably not produced primarily by improper methods of 

 fertilisation, but seems to be considerably affected by the use of 

 fertilisers and methods of cultivation. Groves in which cow- 



