The Cabbage Root Maggot. 551 



gardener had saved his plants by sifting powdered tobacco on them, enough 

 to lay a fine dust on the leaves, and repeating the application if it was scat- 

 tered by wind or rain. It was stated that the fly would not alight upon the 

 dusted plants to deposit its eggs. In 1877, Mr. Garfield, of Michigan, used 

 a strong decoction of tobacco on cabbage while yet in the seed bed and after 

 transplanting in the field, but it did not prevent the fly from laying her eggs. 

 In 1885, Mr. GofFhad no success in preventing the attacks of the maggots on 

 radishes by the use of 1 iberal dressings of finely-cut tobacco leaves. However, 

 the application was made rather late, for many of the eggs may have already 

 hatched and the maggots have begun work ; so the experiment is not con- 

 clusive. 



In planning the preventive experiments to be tried on our plot on Long 

 Island this year, it was decided to test tobacco dust ; for it has the merits of 

 cheapness (costing from i to 3 cents per pound), it is easily applied, has fer- 

 tilizing qualities, and its use would thus be practicable. On April 18 the 

 cabbages were set in six rows, running east and west, of about 300 plants 

 each. The plot was divided into practically equal parts by a north and south 

 division line. The following diagram represents the plan of the preventive 

 experiments ; the treated rows being represented by the name of the preven- 

 tive used on each, and the word "untreated" represents the other rows: 



NORTH. 



1st row : Tobacco Dust 

 2nd row : untreated 

 H 3rd row : Paper Pads 



to 



4th row : untreated 



5th row : Carbolic Acid Emulsion 



6th row : Paper Pads 



SOUTH 



Paper Pads 



untreated 



Carbolic Acid Emulsion S 



untreated |§ 



Paper Pads 



Tobacco Dust 



Thus two whole rows were to be left untreated as checks, and tobaoco dust 

 used on two widely separated half-rows. 



Apiil 19, the day after the plants were set, we applied the dust. All the 

 dust that could be grasped in one hand sufficed for three plants, choroughly 

 dusting each plant and covering the ground close to the stem ; at this rate, 

 7 lbs. of the dust treated about 300 plants once. April 30, a second similar 

 application was made by Mr. Reeve at our request. At that time he report- 

 ed that the plants were all looking healthy and showed no differences ; he 

 noted a good many flies about the plants. May 15, we had Mr. Reeve treat 

 the west half of the first row with the dust a third time, to thus test the effect 

 of two and three treatments. May 21, we examined the plot and found 

 that chickens had destroyed about 25 plants on the west end of each row ; 

 however, this interfered but little with the general results of the preventive 

 treatments which were then quite noticeable The maggots were then at 

 their worst, and there were scarcely 50 plants in either of the untreated rows 

 that had not wilted. While about }i of those treated with tobacco dust had 



