47 



gin to rise, it injures most of them and is nothing else than a very sharp and 

 biting dew, originating in the earthy vapors and conducted from them .... 

 In the third place a disease occurs among trees, which is called sunblight, or 

 blight, urcdo, which, however,_may be of two kinds. First, when a fine rain 

 or dew falls or settles on the leaves while the sun shines, the ducts or tubes, 

 becoming flabby and distended, are contracted at once by the heat of the sun. 

 Thus the leaves are scorched, begin to turn brown and black and fall. In 

 the second case, the urcdo or blight is found in the inner parts of the trees, 

 in the pith .... The true cause, however, for the blighted pith, when 

 the tree is transplanted, may well be, that the common gardeners have the 

 habit, in transplanting, of pruning all the roots and do not understand how 

 much they are injuring the tree. For the smallest roots draw the most sap 

 from the earth, and these are the ones they cut off .... Now because 

 the root, together with the pith, is open and exposed, moisture can penetrate 

 and injure the pith . . . ." 



In regard to canker, we find the "ascending sap" emphasized as its 

 cause in the horticultural lexicon by Riedel published in 175 1". "Can- 

 ker, tree-cancer, canker, devourer," thus is listed the injurious attack 

 on the trees which appears in the bark, — since it forms hummocks here and 

 there and springs up. — And therefore, if the devouring evil is not overcome 

 in time, one branch after another, and eventually the whole tree, is ruined 

 . . . . The real cause, however, of this injurious attack on the trees is 

 cither the evil peculiarity of the earth and the evil juices produced or arising 

 from it which become so inflamed within the bark that this looks black when 

 removed, or the ascending superfluous rank juice, which, finding no escape, 

 must clog and spoil, thus becoming the cause of the out-pushing and bursting 

 of the bark." 



Instead of the ascending sap, the expression — "congestion of the sap," 

 is used at present. 



As a remedy for canker, this author recommends cutting out the dis- 

 eased places and coating with grafting wax. If the cause lies in the soil, this 

 should be removed up to the roots and replaced by new soil. When the sap 

 is excessive, the base of the tree trunk should be bored in February, and the 

 hole wedged open for i to 2 days with a firm wooden peg or a strong root 

 should be split, " since the superfluous sap will then be drawn downward." 



Philipp Miller- traces phenomena of disease directly back to frost, 

 and calls them "blight." Miller's decisions are essentially a repetition 

 of Hale's theories that by blight (blast) not only frost but also sun scorch 

 etc. are understood. Hale's'' statements are important because he men- 

 tions the transmissabiHty of canker in budding and of its occasional heal- 

 ing by being cut out. The observation of this English experimentor on the 



1 Riedel, Kurz abgefafstes Gartenlexiron usw. Nordhausen 1751. p. 420. 



2 The English Garden Book or Philipp Miller's "Gardener's Lexicon etc. 

 From the Fifth Edition translated into the German by Huth. Nurnberg 1750. p. 136. 



3 Statical Essays containing- Vegetable Statics etc. by Steph. Hales. 2nd edition. 

 London 1731. L 35ff., 147, 369; II, 265. 



