55^ 



drew attention to the fact that this fungus, which Frank at first liad de- 

 scribed as Cytospora rnhesccns, was not able to produce the disease but 

 should be considered as a secondary phenomenon, just like the simultaneous 

 occurrence of bacteria. Aderholt' first cited the experimental proof that 

 Valsa is not able to penetrate at once into healthy tissue. This investi- 

 gator found, in his artificial freezing experiments, that the co-operation of 

 late frosts w^as unmistakable in the growth of fungus. 



In regard to the abo\e named fungus, Aderholt is of the opinion that 

 if the fungus reciuires, for its infection, the injury produced b\- frost or 

 some other good cause, it still is able to strengthen itself later so much that 

 it can spread parasitically. This theory agrees perfectly with that of 

 Vuillemin- in regard to the cherry disease observed in Lorraine in 1887, 

 which bears great similarity to the one here discussed; Coryneum Beijer- 

 inckii is named as the cause, and the author associates with it /Iscospora 

 Reijcrinckii as the ascospore stage. It would thus seem to be the theory 

 of the above investigator that climatic causes have produced the condition 

 for the disease but the fungus produced the disease itself. Accordingly, 

 in combatting this disease, all wood infested with Valsa or its conidial 

 form, the Cytospora, must be carefully destroyed. 



However, we obtain an insight into the real relation of this fungus to 

 the disease only from the very recent inoculation experiments which 

 Liistner" has carried out. Among others, he took two small cherry trees 

 of different varieties and broke back their crowns. The end broken and 

 the piece of the trunk left standing were inoculated with the conidia of the 

 fungus and also later painted with water containing them. Since the crown 

 did not die back as a result of the breaking, it was later cut oiY and tied on 

 to the trunk. \\\ the end of October the fungus, as shown in Fig. 120 at 

 the places marked with an X , had spread over the broken and dead end of 

 the tip, while the remaining part of the trunk, although inoculated in the 

 same way, remained perfectly healthy and continued to grow. The wound 

 due to inoculation had healed normally. 



Liistner quotes similar results from I'eijerinck and I\ant\ who could 

 not produce a gummy exudation on peaches and cherries with Cytospora. 

 and report nothing as to the death of the inoculated branches. 



Suj)ported by these experiments and my personal observations, I con- 

 sidered not only the disease under discussion but also the others produced 

 by varieties of Valsa, or their pycnidial forms, as occurring with the 

 co-operation of parasites of weakness, in which only the appearance of 

 disease was determined bv the fungus. Tlie fungi are able to infest the 



1 Adcrhold, R., f)ber das Kirschbaumsterben am Rhein. seine Ursachen un«l 

 seine Bekampfung. Arb. d. Biolog. Abt. f. l^and- u. Forstw. um Kais. Gesundheit- 

 samte. Berlin 1903, P. Parey u. .1. Springer, v. Ill, Part 4. 



2 Vuillemin, Paul, Titres et travaux scientifiques. Paris, Typographie, A. Davy 

 1890, 4o. 



3 Liistner G., Beobachtungen iiber das rheinische Kirschbaumsterben. Bericht 

 d. Kgl. Lehranstalt, fiir Wein-, Obst- und Gartenbau zu Geisenheim a. Rh. f. d. 

 Jahr 1905, von Prof. Wortmann. Berlin, I'aul l-'arey 1906, p. 122. 



4 Centrallilatt fiir Bakteriologie und I'arasitenkunde, I'art II, v. lii, p. 374. 



