468 CITRUS FRUITS AND THEIR CULTURE. 



Cattle-penning; deep-setting; a wet, soggy soil con- 

 dition; the use of rank, organic nitrogenous fertilizers; 

 planting in localities underlaid with hard-pan; faulty 

 drainage ; a shaded condition of the soil, and many similar 

 circumstances and practices have been given as the cause 

 of foot-rot. While it is not probable that the disorder 

 is due to any of these, there is no doubt that they have 

 a deleterious effect on the general health of the tree, and 

 so act as a predisposing cause. A healthy, vigorous tree 

 has all the chances in its favor for withstanding the in- 

 roads of disease, and any decrease in its vitality simply 

 gives its enemies an opportunity to gain a foot-hold. 



The specific cause of the disease is still in doubt, but 

 it is probably due to some form of vegetable parasite. 

 Prof. Giovanni Brioze,* in 1878, found a fungus, Fusis- 

 porium limonii, constantly associated with the disorder, 

 but was not certain as to whether it was the specific 

 cause or not. Regarding it he states: "But that its 

 presence ought to accelerate the disorganization of the 

 tissue and contribute to extend the evil, I think I see 

 without any doubt." 



As pointed out above, there are man} 7 conditions 

 which bear an important relation to foot-rot, and a brief 

 discussion of some of these will not be out of place, (a) 

 Cattle-penning and pasturing, so often resorted to for 

 the purpose of fertilizing the groves, is, to say the least, 

 a questionable practice. The sharp hoofs of the animals 

 cut and bruise the bark on the crown roots, and thus, 

 through their agency, this possibly parasitic disease may 

 be more rapidly carried from affected to unaffected trees. 



* Intorno al Mai Goma Delgi Agrumi, Stations Chimico-Agraia 

 _ erimentale Di Roma. pp. 1-16, pi. I. 1878. 

 Series 3a Atta della R. Academia del Lincei.) 



Sperimentale Di Roma. pp. 1-16, pi. I. 1878. (Estrata dal Vol. 11, 



de 



