132 SEVENTEENTH REPORT. 



sudden withering and blighting of the tops is commonly construed 

 to mean that the trees are dying. 



The Phyllosticta Disease of Horse-cJusstnut. Of similar nature to 

 the above diseases is the disease of horse-chestnut caused by Phyl- 

 losticta paviae Desm. (PL X.) No doubt the great vitality of the 

 tree can stand the occasional defoliation, but the effect v-pon the 

 householder is verj'^ much more severe! The accompanying cut 

 shows the striking effect upon the leaves. In the usual attack upon 

 the shade tree aside from the litter and the unsightly appearance 

 little damage is done to the full-grown tree. The writer has ob- 

 served complete defoliation and great stunting of growth of young 

 horse-chestnut trees in a row in the nursery. 



On the ])oint of seriousness, these three diseases are very insig- 

 nificant in comparison with the great loss of trees which occurs 

 each year because of the gradual encroachment of heart rots upon 

 the sound wood of the maples. It is very difficult to find trees 

 which do not show more or less stag-head appearance. It seems 

 safe to predict that at the present rate of deterioration the present 

 mature trees which line the lawns -mW be rendered worthless for 

 shade in from 15 to 25 years. 



SUMMARY 



In this preliminary article, the present extent of Curly Dwarf 

 and Leaf Roll of potato has been outlined. The cucumber disease 

 situation is seen to be a serious once. A new disease of unknown 

 cause, is described tor the first time and the name "white pickle'' 

 given b}' the growers is retained because of its descriptive value. 

 A celery disease which has already done great damage is described. 

 This disease has been found to be caused by a bacterial organism 

 which produces its effects by plugging the vascular system. For 

 this disease the name Stunting Disease of Celery is proposed. 

 Attention is called to Sclerotmia Uhertiana Fckl. as a trench rot 

 of celen' and as a disease of greenhouse lettuce. Each of these 

 cases were of interest because of the more or less definite history 

 of the introduction of the parasite which could be traced. The 

 Black Rot of Lettuce has been found associated with Rhizoctonia. 

 An undescribed disease of lettuce which gives indication of being a 

 bacterial disease of similar nature to the Stunting Disease of Celery 

 is given a similar name, Stunting Disease of I>ettuce. This disease 

 although presenting the symptoms of I^ettuce Rosette shows no 

 connection with Rhizoctonia. 



