The Rhizoctonia Damping-Off of Conifers 7 



number of tests with mercuric chloride. In a later paper, Hartley (1915) 

 points out that this material caused severe chemical injury, as was 

 evidenced by the killing of dormant seed. The writer (Wiant, 1927), 

 however, using much weaker concentrations than those employed by 

 Hartley, obtained excellent results with mercuric chloride on coniferous 

 seedbeds. 



During the past several years, a number of commercial fungicidal 

 preparations have appeared which contain as their toxic principle various 

 organic mercury compounds, such as chlorophenol mercury, cyancresol 

 mercury, and nitrophenol mercury. The first published account of the 

 use of these preparations for the control of damping-off of conifers is that 

 of the writer (Wiant, 1927), who points out their effectiveness when used 

 both in solution and in the dry form. May and Young (1927), whose 

 paper has already been referred to, used several of the organic mercury 

 preparations in small-scale experiments. 



The following papers deal with the use of a number of organic and 

 inorganic mercury compounds for controlling Rhizoctonia causing damping- 

 off of vegetable seedlings and brown patch of turf. Rosen (1924) states 

 that chlorophenol mercury is effective in controlling Rhizoctonia damping- 

 off of cotton. Gloyer and Glasgow (1924, a and b) found that mercuric 

 chloride successfully controlled Rhizoctonia attacking cabbage. Clayton 

 (1926), using chlorophenol mercury, cyancresol mercury, mercuric chloride, 

 and nitrophenol mercury, failed to control damping-off in cruciferous 

 seedbeds, but suggests as a possible explanation the fact that the first 

 applications were made two weeks after emergence had occurred. H. E. 

 Thomas (1927) found chlorophenol mercury and mercuric chloride effective 

 for controlling Rhizoctonia damping-off in flats of cabbage and tomato. 

 Small (1927) reports success with chlorophenol mercury in controlling 

 foot-rot of tomato caused by Rhizoctonia. Coons and Stewart (1927) 

 found that dusting sugar-beet seed-balls with chlorophenol mercury 

 reduced the infection from soil-borne Rhizoctonia. A similar effect from 

 liquid treatments with the same chemical on garden beets is reported by 

 McWhorter (1927). 



Both mercurous chloride and mercuric chloride were unsuccessfully 

 employed in preliminary experiments by Piper and Oakley (1921) and by 

 Oakley (1924) for controlling the brown patch of turf. Godfrey (1925) 

 later demonstrated the effectiveness of chlorophenol mercury against 

 that disease. Monteith (1925 a) reports similar results, but finds nitro- 

 phenol mercury ineffective. Monteith (1925 b, 1926), and Monteith 

 and Harmon (1927), report extensive tests with a large number of organic 

 and inorganic compounds of mercury, many of which, including mercuric 

 chloride, were effective. They conclude, however, that mercurous chloride 

 was the most satisfactory from the standpoints of control, toxicity, and 

 cost. 



