REPORT OF THE SOCIETY 45 



Control 



A lead arsenate spray of the usual strength of \}/2 lbs. of powder to 40 gal- 

 lons of water will hold the larvae in check, and should be applied in earl}' summer 

 for the best results. 



Raking the leaves and rubbish into piles away from the trees and burning 

 same, where this can be feasibly done, will act as a good control. Some farmers 

 object to this method on the ground that their trees are often injured by the fire. 

 However, if carefully carried out, burning should not damage the trees and it 

 certainly will kill off enormous numbers of the pupae. This work can be done 

 best late in the fall, or sometime in spring during the last of April or very early in 

 May. Two factors enter into leaf-burning operations, viz. , humidity and wind. 

 If the weather is damp it is a waste of time to attempt burning; on the other 

 hand if too dry burning becomes dangerous. Morning hours are not good for 

 starting a fire because the wind is apt to rise after the sun gets well up. 

 whereas in the afternoon the maximum temperature of the day has been 

 reached by 2 p. m. and the tendenc}^ then will be for the wind to fall again, 

 making it easier to extinguish fires at night fall. The question of burning for 

 the control of the Maple Leaf Cutter is to be taken up more thoroughly 

 this coming summer; the results of which will be pubHshed in due course of 

 time. 



PHYSIOLOGICAL SPECIALIZATION OF COLLETOTRICHUM LINDE- 

 MUTHIANUM IN EASTERN CANADA. 



By K. A. Harrison, B.S.A., M. Sc. 



Introduction. 



A general study was made during the past winter in the laboratory and 

 greenhouses of the Dept. of Botany at Macdonald College of the organism cau- 

 sing a very common disease of beans, and the following article reports on the 

 most interesting phase of the work. While beans cannot be classed as a major 

 crop in Canada still they are important enough to be considered as a staple one 

 and of greater proportional importance to Quebec than the rest of Canada. 

 The acreage and yield of field beans, the only ones of which it has been possible 

 to secure statistics, has been decreasing since the war. The following table 

 illustrates certain of these facts clearly and was compiled from the ^Monthly 

 Bulletin of Agricultural Statistics (4). 



