SOIL TREATMENTS AND SEED GERMINATION 31 



Capper Sulfocarbolate 



Copper sulfocarbolate, up to 4.5 gm., gave less satisfactory control of damping- 

 off than did some other copper salts; and 4.5 gm., although not at all injurious to 

 hollyhock, was injurious to ten-weeks stock, Petunia, Myosotis, Ageratum, 

 Salpiglossis, sweet pea, beet, and cucumber. 



Copper Aceto-arsenite 



Copper aceto-arsenite (Paris green) 0.5 gm. did not control damping-off, but 

 there was little of the disease with 1.0 gm., less with 1.5 or 2 gm., and usually 

 none with 2.5 gm. or more. Applications of more than 1.5 gm. were unsafe, how- 

 ever, for they injured the germination of seeds of all species used except hollyhock. 

 Harmful effects on growth were even more evident, as little as 0.5 gm. injuring 

 pyrethruni and Myosotis, while 1.0 gm. was toxic also to seedlings of sweet pea, 

 Salpiglossis, Ageratum, marigold, Leiophyllum, Laburnum, and arbor-vitae. 

 Holl^'hock was the species most tolerant of this as of the other copper salts, being 

 uninjured by 2.0 gm., and it was the only species protected against damping-ofif 

 by copper aceto-arsenite without some chemical injury. 



Copper Carbonate 



According to Newhall and his associates (70), copper carbonate may be applied 

 to soil at the rate of 1 pound to 100 square feet, which is about 4.5 gm. per square 

 foot; but, as used by other investigators (71, 6), 4.0 gm. injured tobacco, and in 

 the work of the writer, more than 4.0 gm. injured the germination of all species 

 except hollyhock. Even lighter applications interfered with growth, cucumber 

 being injured by 2.0 gm., Delphinium by 3.0 gm., and Ageratum, Petunia, and 

 Salpiglossis by 3.5 gm. 



Of the species used, only hollyhock ana possibly beet showed sufficient lack of 

 chemical injury to suggest that copper carbonate in effective quantities may be 

 used safely with them, for less than 4.0 gm. did not satisfactorily control damping- 

 ofT. Hollyhock was the species most tolerant of this as of other copper salts, and 

 although injured by 6.0 gm., it was not at all affected by 5.0 gm. or less. 



Copper Sulfate 



Copper sulfate 3 to 4 gm. usually lessened the severity of damping-off, but the 

 disease was not often wholly controlled by less than 4.5 gm. Germination was 

 also improved by 3 to 5 gm. and with this as with other copper salts, there was 

 usually less chemical injury to germination than to growth. 



Copper Sulfate Growth Injured Copper Sulfate Growth Injured 



Grams Grams 



1.5 Canterbury bells 3 Snapdragon 



Mignonette 



2 Anemone coronaria Ageratum 



Viola cornuta Salpiglossis 



2.5 Calendula 3.5 Sweet pea 



China aster Cucumber 



Beet 



Hollyhock, growth of which was uninjured by 4.5 gm., was the only species 

 with which copper sulfate, in quantities really effective against damping off, 

 was used without too much chemical injur\'. 



