TRANSACTIONS OF THE SOCIETY. 25 



the bark is strong, which, if slightly opened with a knife, will yield to the 

 pressure, and the fungus soon appears. 



While this fungus is young and tender, the Curculio finds it a conveni- 

 ent receptacle for his eggs, the juice of which affords abundant nutriment 

 for the larvse. A pretty sure sign by which you may know that he has 

 used it for that purpose, is a small drop of gum oozing from its surface ; 

 and where you do not see this sign, you may not expect to find his larva 

 within. 



I have said that this disease begins in the part called the alburnum. 

 This is the texture through which the sap ascends; but it soon involves 

 every texture of the tree — wood and bark — and is malignant and surely 

 fatal to the limb on which it grows. It is as destructive to the tree as can- 

 cer is to the human flesh. These fungi always die the succeeding winter, 

 never live over winter, and remain upon the tree, unless removed, a black, 

 unsightly mass. 



I have observed two trees, both of a kind, and nearly of a size, but 

 standing apart and differently located ; one would be diseased with the ex- 

 crescences, and the other would not, while the fruit of both would be 

 nearly alike injured by the Curculio ; and this fact I consider additional 

 evidence that the Curculio is not the cause. 



It is desirable both to find a remedy when a tree is diseased, and also a 

 means of prevention. The only remedy I know of, is to cut the tumor out, 

 and this should be done as early as possible If done early, and with 

 care, the wound soon heals, and the limb is but slightly injured. 



But a means of prevention is more desirable than a remedy. 



A tree of most of the kinds of plums which may be obtained at nurse- 

 ries, if placed on a somewhat gravelly soil, whose power to retain water is 

 small, and, therefore, subject to sudden transition from a moist to a dry 

 condition of its roots every season, I will venture to say, will be diseased. 



I do not mean that there may not be an exception, and that all kinds are 

 equally subject to it ; but I know of no exception, among a number of va- 

 rieties, which have been cultivated under my observation. 



I am inclined to the opinion, that a prevention may be found in cultivat- 

 ing the plum in a loamy soil, rather moist, and in keeping that soil uni- 

 form as to moisture and richness. 



Any kind of tree is not in the condition in which nature would place it 

 and keep it, when the soil over its roots is kept naked and exposed to the 

 burning and drying suns of summer, or uncovered and unprotected from 

 the sudden and intense cold of winter. 



Neither can fruit trees prosper so well in grass land ; for, though the 

 covering of grass may serve as protection from extreme heat or cold, yet 

 it will take from the soil the nourishment which should go to the tree. 



The roots of forest trees are kept in a uniform condition by the 

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