8 MASS. EXPERIMENT STATION BULLETIN 394 



Table 4. — Effect of Salicylic Acid on Control of Damping-off 



Salicylic Acid' 



Relative Number ol Percentages Which 



Plants Which Lived Damped-off 



Beet Cress Pepper Beet Cress 



None (check) 100 100 100 16 13 



5.0 gm per square foot 410 157 136 3 



6 gm. pel square foot 416 157 165 C 



7.5 gm. per square f of t 521 ... ... 



*In 1 quart of water. 



Formic Add 



Formic acid is sufficiently effective as a soil fungicide to warrant turther in- 

 vestigation, but it is not safe enough to be recommended to growers until more is 

 learned about hew to use it. When a dust containing 9 cc. formic acid (in 38 gm. 

 powdered charcoal) per square toot was well worked into soil immediateh' before 

 seeding, lettuce and beet were uninjured and the number of seedlings which lived 

 was increased 98 percent in the case of beet and 117 percent in the case of lettuce. 

 Formic acid 9 cc. (in 1 quatt water) per square foot, applied immediately before 

 seeding, improved the stands of lettuce but caused some injury to cabbage and 

 cucumber. 



Pyroligneous Acid 



Except for a temporarily retarding effect on early growth of cauliflower, pyro- 

 lignecus acid, 155 cc. per square foot, gave gccd results with several vegetables. 

 Worked into soil immediately before seeding, the undiluted acid improved the 

 stand of beets 367 percent and of lettuce 135 percent. Applied to soil (in 1 quart 

 water per square foot) immediately' after seeding, it improved the stand of tomato 

 by 149 percent, of cauliflower by 100 percent, and of lettuce by 98 percent. 



Oxyquinoline Sulfate 



Oxyquinoline sulfate is known to have fungicidal properties (6, 7). Applied in 

 solutions (1.25 quarts water per square foot) immediately alter seeding, 2 gm. per 

 square foot was safe with all vegetables with which it was used, except cabbage. 

 Damping-off was well controlled by this application and the number of plants 

 which lived was increased as follows: beet, 120 percent; cabbage, 62 percent; 

 cucumber, 107 percent; lettuce, 34 oercent; and pea, 53 percent. Beet and cu- 

 cumber seedlings damped-off to the extent of 43 and 21 percent in untreated soil. 

 In treated soil, these figures fell to 3 and 2 percent, respectively. Oxyquinoline 

 sulfate is, it is evident, effective as a soil fungicide. 



Calcium Cyanamide 



Dam.ping-off is controllable by calcium cyanamide, 10 to 12 gm. per square 

 foot, but it is unsafe to sow seeds until at least 2 weeks after soil treatment (4). 

 This is, however, a good material to use if, for any reason, soil must be tieated 

 long before seeding and then exposed to recontamination: tor soil treated with it 

 's not so promptly reinfested with damping-off fungi as is soil treated with for- 

 maldehyde. When calcium cyanamide, 12 gm. per square foot, was worked into soil 



