The Rhizoctonia Damping-Off of Conifers 



47 



During the season of 1927, an extensive experiment was conducted with 

 applications of aluminum sulfate and both organic and inorganic mercury 

 materials, on beds of this species. The experimental plats were located 

 adjacent to those of the liquid treatments on spruce of that season, with 

 which they are comparable. 



The high incidence of disease in the check plats (table 15) is evidenced 

 not only by the high percentage of damping-off after emergence, but also 

 by the low percentage of emergence. With the exception of the smaller 

 applications of several materials, all of the treatments reduced the disease 

 to a negligible amount (Plate VI, 1 and 2). 



The larger applications of mercuric chloride and mercurous chloride 

 caused medium to severe stunting, similar to that described for several 

 of the liquid treatments on this species. The very slight stunting noted 

 from the smaller applications of these materials is of no practical impor- 

 tance. 



From the data on final stand, it is evident that the two largest applica- 

 tions of aluminum sulfate, the two treatments with Bayer 1 1-6, the larger 

 applications of Bayer dust, Dipdust, and Semesan Bel, and the smaller 

 applications of mercuric chloride and mercurous chloride, were practically 

 equally effective (figure 5). 



/O II 12 /3 14 15 /6 CM 



Figure 5. final stand of norway-spruce seedlings in plats treated with 



dry applications of chemicals 



The numbers below the columns refer to the Ire itment numbers given in table 15 



