552 Bulletin 78. 



succumbed, with no diflference noticeable in those treated two and those 

 treated three times. In August, Mr. Reeve reported that 35 heads were cut 

 from the west half of the first row and 75 heads from the east half of the sixth 

 row. Thus nearly half ot the plants treated with the dust produced salable 

 heads ; while from the untreated rows Mr. Reeve reported only 90 heads from 

 nearly 600 plants set. 



Plants can be treated once with this tobacco dust at a cost of not over one 

 cent for ten plants, and the experiment indicates that it affords some protec- 

 tion, but there were other untreated plants to act as baits. And an examina- 

 tion May 21 of many of the treated plants that were apparently healthy, 

 showed that several maggots were at work on many of them. Therefore, we 

 are not sufficiently convinced of its effectiveness to feel warranted in advis- 

 ing its general use as a preventive against the maggots. 



Carbolic Acid, diluted, emulsified, or combined with Plaster. 



Carbolic Add, diluted. — In 1886, Mr. GofT reported the following results 

 with this substance : "On May 2, we applied this solution at the rate of 3 

 grammes of the acid, to 5 gallons of water, to the soil about the roots of a row 

 of radishes in the garden. On May 11, we renewed the application, doub- 

 ling the amount of the acid. May 18, we repeated it, using 8 grammes of the 

 acid to 5 gallons of water, following with the last named solution on May 23. 

 No benefit resulted from these applications that we were able to detect. It is 

 possible that the plants would have borne a still stronger solution, which 

 might have been efficacious. " We believe it would have been effective if 

 used stronger, but it is our experience that it is just as effective, perhaps 

 more so, and not so liable to injure the plants if applied in the form of an 

 emulsion. 



Carbolic Acid Emulsion. — This preventive was first suggested by Prof. 

 Cook in 1881. He then made an emulsion by dissolving 2 qts. of soft soap 

 in 2 gals, of water, and then adding i pint oi crude carbolic acid, thoroughly 

 agitating the mixture which soon formed a stable emulsion. To every pint 

 of this standard emulsion he used 50 pints of water to dilute it before apply- 

 ing; thus the acid was used on the plants at the rate of a pint to about 125 

 gals, of water. He got excellent results by sprinkling the radish plants as 

 soon as they were up, and thereafter every week or ten days. In 1886, Prof. 

 Cook again experimented with this emulsion, but made it with i lb. soap, i 

 gal. water, and % gal. crude carbolic acid ; diluted with 75 parts of water. 

 The acid was thus used at the rate of about i pint to 28 gallons of water, or 

 over 4 times as strong as he used it in 18S1. This was applied to cabbages, a 

 tablespoonful to each plant, at intervals of from 4 to 7 days for 3 weeks, with 

 the result that only 5 out of 21 treated plants were injured by the maggots, 

 while 16 out of 24 untreated ones were attacked ; the plants were uninjured. 

 He also used the same strength of emulsion on radishes, a teaspoon ful to 

 each plant, with the result that 5 out of 18 treated plants were found infested, 

 while 22 out of 32 untreated ones were badly injured ; all of the plants, how- 

 ever, were injured by the liquid Prof Cook seems not to have tried the 



