Conclusion of the List of Pests 361 



infested patches by dipping the crowns and roots in kerosene 

 emulsion, or tobacco extract. Fumigation. 



SAW-FLY (Emphytus maculatus) . Larva nearly % in long, 

 greenish, feeding upon the leaves; two broods. 



Hellebore; arsenicals for second brood. 



Walnut. BLIGHT (Pseudomonas juglandis). Appears as a black 

 spotting of the fruit and as black cankers on the stems. The 

 twigs and fruit-spurs are killed. 



Control. None, except those ways mentioned under pear- 

 blight (page 357) ; grow immune varieties. 



ANTHRACNOSE or LEAF-BLIGHT (Marsonia juglandis). The 

 same disease that attacks hickory (see page 356). 



ARSENICAL POISONING OF FRUIT TREES 



In the first edition of this work, the question was 

 asked as to what becomes of the arsenic that finally 

 reaches the soil from the sprays. From the few studies 

 that had then been made of the subject (Cornell Bull. No. 

 101) it was concluded that the arsenites do not leach 

 from the soil, but "remain where they fall, the same as 

 sand does, and are carried down only when there are 

 crevices or other openings in the soil, and they go down as 

 insoluble compounds, and, to a slight extent, by the mere 

 mechanical action of the water." In the early days of 

 spraying, the question of the effect of the materials on the 

 soil and on live-stock feeding on the grass beneath the 

 sprayed trees (as also on persons eating sprayed fruit) 

 was much discussed. The subject of soil injury was gone 

 over carefully by Lodeman in his "Spraying of Plants," 

 1896, and the experiments at that time had shown no 

 danger following the customary use of the arsenic and the 

 copper salts in spraying. "The only conclusion to be drawn 

 from these extracts," he says, "is that proper applications 

 of insecticides and fungicides will apparently never cause 



