54 



PHOSPHORIC ACID, 



Phosphoric acid, which is a very necessary element of fertilisation on 

 Florida orange lands, is mostly used in the form of dissolved bone- 

 black, acidulated bone or phosphate rock, soft phosphate, raw bone, 

 guano, etc. The immediate effect of phosphoric acid on the orange tree 

 and fruit is little understood. Several intelligent growers claim to be 

 able to recognize the effect of phosphorous starvation by the appear- 

 ance of the new growth of leaves. If these, when they first push out 

 or while they are still young and tender, present a slightly variegated 

 appearance, mottled with light and dark green, it is claimed that they 

 are suffering from lack of phosphorus, and that if a liberal application 

 of some soluble phosphate is applied this appearance may be checked 

 If this can be shown to be true it will prove a valuable index to the 

 available quantity of phosphoric acid in the soil. A similar appear- 

 ance, may however, appear In light cases of the so-called " frenching," 

 a disease, or probably more properly a symptom of disease, which is 

 not uncommon. Phosphorous starvation, it is true, may have soma 

 effect in inducting this disease. 



LIME. 



Lime, it is usually supposed, is present in sufficient quantities in most 

 of our soils. It may be questioned, however, whether the common high 

 pine land and sciub land, and indeed much of the flat woods and ham- 

 mock of the interior of Florida, might not be benefited by dressings of 

 lime. From the superiority of oranges grown on soils which are known 

 to be rich in lime it would seem that this is probably a very desirable 

 and necessary element for the production of superior fruit. The fine, 

 smooth-skinned, and deliciously flavoured Indian and Halifax River 

 oranges, with their characteristic aroma, are grown largely on soils rich 

 in lime from shell mounds and coralline and coquina rock. The oranges 

 produced in the noted Orange Bend Hammock, which are of distinctive 

 quality, with delicate, rich aroma, and thin, smooth rind, are produced 

 on a soil underlaid by a marl rich in lime. Lime soils are in many orange 

 countries considered superior for orange growing. Dr. A. Stutzer, in 

 his work on the Fertilisation of Tropical Cultivated Plants, writes : 

 " The orange and citron fruits desire a deep, porous, dry soil, rich in lime. 

 If sufficient lime is not present the fruit will be thick-skinned and not 

 have a fine aroma." It appears also that the effect of abundant lime 

 is to hasten to some extent the time of ripening. Fruits grown on soils 

 rich in lime appear to colour and become suitable for shipping some- 

 what earlier than those grown on soils containing but little lime. To 

 secure a good quality of fruit the regular application of lime may be 

 found very desirable in many groves 



FERTILISATION AS AFFECTING DISEASE. 



Probably the most common cause of injury to orange trees is a lack 

 of fertilisation, yet it is not frequent for disease to be induced or 

 aggravated by excessive or improper fertilisation. This may, indeed, 

 be of much more importance than we are at present inclined to believe. 

 One of the forms of die-back, a common and destructive disease of the 

 orange, is quite evidently due to errors in fertilisation. In other cases 

 he disease appears to be caused by planting in improper soil. 



