May 20, 1921] 



SCIENCE 



485 



Of particular concern, from the practical 

 viewpoint, is tiie effect of dormant lime sul- 

 fur and copper sulphate sprays upon the 

 pycnospores lodged in the pycnidia and des- 

 tined to function after petal-fall. 



Wallace^ in his official reports and Douglas* 

 have repeatedly published the statement that 

 a very strong solution of lime sulfur, applied 

 before the buds begin to swell, perfectly con- 

 trolled this disease and that the summer 

 sprays, consequently, were unnecessary. The 

 writer disagrees with their views, but has dis- 

 covered from field and laboratory experiments 

 and obervations, the scientific explanation of 

 partial control by the dormant sprays applied 

 late. 



The infectious surface of an apple blotcli 

 canker in the first season of its fimctional 

 activity consists of two distinct portions : 

 first, that portion which develops from a 

 single infection, becoming apparent in late 

 summer and ceasing its active gTowth upon 

 the appearance of cold weather; second, that 

 porton which advances from the initial canker 

 the following spring, approximately two weeks 

 after the buds burst open, and which becomes 

 dotted with pycnidia, with mature pycno- 

 spores, simultaneously with the advance of the 

 canker. The first portion is the initial canker 

 and bears pseudo-pycnidia. The contents of 

 the pseudo-pycnidia are completely or par- 

 tially differentiated into spores by the time 

 it is customary to apply the dormant spray. 

 Furthermore, the epidermal covering over the 

 pycnidia is ruptured, exposing the pycnidial 

 wall. The season's young fruits and new 

 growth are, therefore, subject to two distinct 

 sources of infection from the young blotch 

 cankers. 



A dormant spray of lime sulfur applied as 

 the buds begin to swell actually kills the 

 spores and sporidal layer within the differen- 

 tiated pseudo-pycnidia but has absolutely no 



1 Wallace, F. N., 9th Annual Eeport Indiana 

 State Entomologist, 1915-16, pp. 51, 54. 



2 Douglas, B. W., ' ' War aad the Fruit 

 Grower," Country Gentleman, Septemlier 14, 1918; 

 "Fmit Diseases of 1919," Country Gentleman, 

 April 17, 1920. 



effect upon the mycelium of the organism 

 ramifying throughout the cortical tissue be- 

 neath. The toxic effect upon the spores is 

 very striking after the first rain following 

 the dormant spray. Dilutions of lime sulfur 

 of 1-3, 1-5, 1-6, and 1-8, were given their 

 trial and all were similarly toxic to the spores 

 in the pycnidia, but it appeared that dilutions 

 somewhat stronger than 1-8 were more effi- 

 cient. A dilution of copper sulphate (1-6) 

 produces similar toxic effects. Scalecide pro- 

 duces none at all. 



As was mentioned above, a new infectious 

 area advaoces from the initial canker in the 

 spring. It follows, therefore, that the dor- 

 mant spray exercises but very little control 

 upon the season's infection of the young 

 apples and new growth. 



E. F. GuBA 



TJNivEESirT OF Illinois 



CROWS AND STARLINGS 



To THE Editor of Science: Last fall at 

 Devon, Pennsylvania, a man shooting black- 

 birds also wounded a starling, which fell on 

 the grass and which he could not find. 

 Shortly afterwards several crows were seen 

 diving at something in the grass and then 

 lighting and running through the grass after 

 it. Upon his going towards them to see what 

 they were doing, they all fiew away, one of 

 them carrying the starling in its bill, and 

 landed on the walk in a neighboring place, 

 where the crows gathered round the starling 

 and proceeded to jjeck at it. He followed 

 them and scared them, and the crows fiew 

 away, abandoning the starling, which was 

 nearly dead. 



I have never before known of crows carry- 

 ing off as large a bird as a starling, though 

 I have seen one carrying off from the nest a 

 young robin nearly ready to fly, and of course 

 they kill many young robins and other young 

 birds of smaller size. 



F. E. Welsh 



THE SYNCHRONAL FLASHING OF FIREFLIES 



During a trip in Siam, a distinct flashing of 

 fireflies in unison was observed. The observa- 



