774 EXPERIMENT STATION RECORD. 



A disease of nursery stock, G. Massee {Gard. Chron., 3. ser., 32 {1902), No. 

 822, p. 235, fig. 1). — The author reports having observed in widely separated parts 

 of England a disease of young apple and plum trees which is due to the attack of the 

 fungus Euti/pe/la jfmnastri. In instances cited more than 50 per cent of the entire 

 stock was destroyed. Peach trees are subject to attacks of the same fungus, the dis- 

 ease on all showing well-marked characters which are easily recognized. The stem 

 is the pait attacked, and the first outward indication of disease is a slight browning 

 of tlie Imrk wliich soon becomes hard, dry, and inseparable from the wood. There 

 is no cracking or wrinkling of the surface and as a rule no further symptoms are evi- 

 dent during the first season of the attack. The mycelium, however, continues to 

 grow inward, killing the cambium and young wood, thus preventing the upward 

 flow of sap. The second season the leaf buds either do not expand at all or only 

 imi^erfectly, and during the summer the branches die through a lack of food. The 

 fungus does not appear to pass from the stem to the branches, the latter dying simply 

 from starvation. The second year after the plant is attacked the tree is usually 

 completely destroyed. At this time the infection of the fungus is indicated by the 

 appearance in the dead bark of groups of minute transverse cracks which contain 

 small clusters of the fruiting organs of the fungus. There is no aj^pearance of any- 

 thing like canker, and as the l>ark is not broken or disturl)ed in any way the super- 

 ficial observer usually l)elieves that the tree is killed l)y drought or some attack on 

 the roots. 



This fungus is common upon many species of rosaceous plants, and the spores pro- 

 duced on the wild plants usually start an epidemic of the disease in the nurseries. 

 Although the infection sometimes takes place through punctures caused by insects, 

 the epidemic occurrence of the disease can only be traced to infection taking place 

 through the cut ends of twigs. The spores of the fungus mature fi-om February to 

 April, and it is recommended that no pruning should be done during this time. In 

 the case of the young stem it is important that every wound made by ])runing should 

 be coated with tar or some substance that would prevent the germination of spores 

 on the surface. Insects, especially aphids, should be held in check by means of 

 insecticides, and wild trees in the neighborhood should be examined for the occur- 

 rence of the fungus. 



Two unusual troubles of apple foliage, F. C. Stewart and H. J. Eustace 

 {New York State Sla. Bui. 220, pp. 217-233, pJx. 5). — During the sunnner of 1902 the 

 attention of the authors was directed to a condition of apple trees over the greater 

 portion of the State, the leaves being much wrinkled and distorted. Different varie- 

 ties of apples seemed to be variously affected, the leaves being more or less covered 

 with irregular blisters of various sizes caused by the separation of the lower epider- 

 mis from the mesophyll. It soon became evident that the blisters were in some way 

 related to frost injury, and a review of the weather conditions showed that the spring 

 of 1902 in New York was unusually wet and cool and there were a number of severe 

 frosts occurring as late as May 10 and 11. Only the early leaves at the base of the 

 shoots were affected and the most injury was observed where frosts were most severe. 



The authors advance a theory for tlie injury which differs somewhat from that 

 lately described by Sorauer. They claim that the leaves were frozen when only 

 partially unfolded. The formation of ice crystals between the lower epidermis and 

 the mesophyll caused these tissues to separate, and being removed from the source of 

 nourishment the epidermis ceased growing while the parenchyma cells contmued to 

 expand. Not having an opportunity to spread laterally the leaf took the form of an 

 arch, bringing about the wrinkled condition. In some cases the epidermis became 

 ruptured and the parenchyma cells of the leaf exposed to the air died fnmi excessive 

 transpirati(jn. This theory differs somewhat from that of Sorauer, who claims that 

 the rupturing of the epidermis and death of the cells is due to the direct action of 

 the frost. 



