555 



sterile in the next year and only bear fruiting wood the year after. Op- 

 posed to this theory, the investigations of Miiller-Thurgau^ have shown 

 that such wood, even in August of the year of its production, can form 

 fruit buds and that the treatment of the vine is to be planned accordingly. 



The Dying of the Cherry Trees Along the Rhine. 



As a special example of the phenomenon previously described, we will 

 consider the disease of the sweet cherry in the provinces of St. Goar, St. 

 Goarshausen and Unterlahn which has been much discussed since the be- 

 ginning of this century. 



According to the material- which 1 obtained from that region, and 

 cases which I obser\ed elsewhere, the phenomenon appears as follows : 

 a turning yellow of the foliage of some branches, or of the whole crown 

 sets in rather suddenly and usually with the appearance of considerable 

 gum exudation; the branches, or even the whole trunk, die. Often the 

 tips of the branches develop further while the rest remains bare. Micro- 

 scopic investigations determine a high degree of gummosis ; gum holes 

 can be found even in the youngest shoots. In the wood and in the bark 

 body, the phenomena of browning are often found, which we will discuss 

 later when describing the action of artificial frost. Indeed these are 

 provable often in the apparently healthy shoots, leaves and fruit stems. In 

 older trees definite forms of tissue clefting are frequently found which 

 correspond with those produced by artificial frosts. Because of this dis- 

 covery, I am of the opinion that not only in the "Dying of the Rhenish 

 cherry tree," but also in similar cases which appear often but usually to a 

 lesser extent, frost action at the time of the spring growth is to be consid- 

 ered as the actual cause. 



G6the-\ who agrees with our theory, describes as follows the weather 

 conditions for the localities lying along the Rhine, in the year when the 

 disease appeared : "The cherries were already in bloom when on the 22nd 

 of March they were surprised by a drop in temperature to 9.7 degrees C. 

 below zero. In the course of the spring abnormally strong fluctuations 

 took place between great cold and great warmth. I consider such weather 

 contrasts to be the cause of the very numerous cases of subsecjuent disease 

 which, in the stone fruits, are almost always connected with strong gum- 

 mosis and are accompanied by infection with wound parasites or parasites 

 of weakness. Also, for the special case on the Rhine, such a fungus Valsa 

 leucostoma was at first made responsible'*. Soon after, however, Wehmer'' 



1 Muller-Thurgau, tJber die Fruchtbarkeit der aus den alteren Teilen der Weln- 

 stocke hervorgehenden Triehe, sowie der sog. Nebentriebe. Der Weinbau 1S82. 

 No. 28. 



- Sorauer, P., Das Kirschbaum.sterben am Rhein. D. Landwirtsch. Presse 1900, 

 p. 201. 



3 Gothe, R., Das Absterben der Kirschenbaume in den Kreisen St. Goar, St. 

 Goarshausen u. Unterlahn. D. Landwirtsch. Presse 1899, p., 1111. 



4 Frank, A. B., in D. Landwirtsch. Presse 1899, No. 83, p. 949. 



s Wehmer, Zum Kirschl^aumsterben am Rhein. D. Landwirtsch. Presse 1899, 

 No. 96. 



