35 



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 questionable, but all 

 evidence indicates that they will 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 com- 

 mon 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 produce the disease. Trees 

 set out on such soil 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 

 considerable loss is incurred by planting and fertilising groves 

 on the die -back soils. The symptoms of die-back are the same 

 whether due to excessive fertilisation or to improper soil con- 

 ditions, and it is probable that the real cause will be found to 

 be the same in both cases. Both forms of the disease appear to 

 be greatly aggravated by excessive cultivation, which 

 apparently destroys the surface roots and forces the tree to 

 feed lower down. 



Treatment. — When the die-back is due to the excessive use 

 of highly nitrogenous organic fertilisers, an effective remedy 

 consists in simply ceasing to cultivate and allowing all weeds 

 to grow. In fertilising omit entirely all highly nitrogenous 

 organic manures, but use about the normal quantity of potash 

 and phospheric acid. As the tree recovers, a small amount of 

 nitrogen should be given preferably in the form of nitrate of 

 soda or sulphate of ammonia until the tree is brought up to its 

 normal condition. If the disease is produced by the close 

 proximity of privies, chicken houses, barns, &c , removing 

 these will usually result in the recovery of the affected trees. 

 In the case of barns which cannot be removed it has been 

 found effective in some cases to dig trenches between the trees 

 and the barn to prevent the feeding roots from running under 

 the former Of course the caution in regard to the use of 

 organic nitrogenous fertilisers given above is applicable in this 

 case also When the malady is caused by planting on die-back 

 lands, treatments vary according to the character of the soil. 

 If the grove is on low wet soil, through drainage will usually 

 be found an effective remedy without other treatment. If the 

 soil is underlaid with hardpan, mulching the trees with pine 

 straw, oak leaves, or something of this nature, and stopping 

 cultivation will allow the feeding roots to develop near the 



