879 



Injury to the Foliage. 



The results of partial or entire defoliation must naturally become 

 apparent in the amount of dry substance produced. The effect varies 

 according to the amount and age of the leaves removed and also the possi- 

 bility of compensation for the lack of foliage by the existing buds and the 

 amount of reserve substances necessary for their unfolding stored in the 

 axis. 



The annual reports on forestry give sufficient examples for forest 

 trees. It is not necessary to go further into this subject he;-e since each 

 separate case must be judged for itself. In the numerous injuries due to 

 caterpillars, for example, the amount of injury depends upon the time and 

 duration of the eating. Reference should be made, in this connection, to 

 Ratzeburg\ He describes, in detail, the influence of defoliation on the 

 annual ring formation of spruces and pines and treats later of deciduous 

 trees". Cieslar's'' experiments show that the anatomical structure of a 

 wood ring, produced after extensive defoliation, was changed (it became 

 much more tender). Under certain circumstances the vessels can be entirely 

 lacking* in wood produced after defoliation. Hartig^' had already proved 

 that a decrease in number of the vessels goes hand injiand with the decrease 

 of foliage. Kny" had already touched on the subject that under certain cir- 

 cumstances double annual rings can be produced. Wieler' showed by 

 experiments that the boundaries between spring and summer wood can be 

 entirely efifaced by changes in nourishment. 



Such effects can also occur in fruit trees and often manifest themselves 

 in the yield. In only a few cases can a partial defoliation prove to be advis- 

 able agriculturally as, for example, in grapevines, if they constantly produce 

 new foliage shoots which use up the supply of nutrition necessary for the 

 maturing of the grapes. 



Among annual and biennial cultivated plants, beets come especially 

 under consideration because, in years when fodder is scarce, the older leaves 

 are broken off in the course of the summer and used to feed the cattle. An 

 example from Bohemia- proves that the root body is thereby forced to form 

 more new foliage than it would otherwise and that the storage of reserve 

 substances suffers from this. It was found here that, after defoliation, not 

 only did the beet root remain smaller but the sugar content was about lO 



1 Ratzeburg, Waldverderbni.s, I, p. 160, 234, etc. 



2 Loc. cit. II, p. 154, 190, 233. 



3 Cieslar, A., tjber den Einfluss verschiedenartig-er Entnadelung- auf Grnsse und 

 Form des Zuwachses der Schwarzfohre. Cit. Just's Jahresber. 1900, II, p. 278. 



4 Lutz, K. G., Beitrage zur Physiologie der Holzgewachse. Ber. D. Bot. Ges. 

 1S95, p. 185. 



c Hartig, R., tJber Dickenwachstum und Jahrringbildung. Cit. Zeitschr. f. 

 Pflanzenkr. 1892, p. 292. 



« Verhandl. d. Bot. V. d. Prov. Brandenburg 1879. 



7 Wieler, A., Tiber Beziehungen zwisclien dem sekundaren Diclvenwachstum und 

 den Ernahrungsverhaltni.ssen der Baume. Tliarander forstl. Jalirb. 1892, V. 42. 



s Blatter f. Zuckerrubenbau. 1905, No. 20. 



