38 The Bulletin, 



various cabbage worms. To one who has never tried it, and who has 

 not fully reasoned the matter out, it might seem that this would be 

 dangerous, therefore we propose here to discuss the matter carefully and 

 show why there is no really appreciable danger. 



In the first place it is assumed that the cabbage grower will exercise 

 ordinary good sense and judgment in applying poisons (or any other 

 remedies) to his plants. It is never necessary to cover a leaf or plant 

 with a thick coat of Paris green, just a light even dusting (o?ie ounce 

 Paris green mixed into one pound lime) is all that is usually necessary. 

 It is assumed that no grower Avill poison his cabbage just a day or two 

 before it is cut, for that would not give time enough to do much good; 

 the poison is to protect the growing plants, and there is no occasion for 

 applying it when the cabbage is entirely matured. Cabbage which are 

 well protected during their growth will not suffer much from slight 

 attack when grown. Treatments with poison should not be given 

 within two or three weeks of the time the cabbage is to be cut. Let it 

 be clearly understood that Ave do not recommend a wasteful application 

 of paris green, or that it be applied at any and all times, but we do 

 recommend light dusting applications (one ounce paris green to one 

 pound lime) from time to time during the growing season, the treat- 

 ments to be stopped two or three weeks before the cabbage is to be cut. 

 This policy is abundantly safe. 



But the reader may want further assurance. In October, 1908, Mr. 

 Metcalf, Assistant Entomologist, working under directions of the writer, 

 made a test of this mixture on collards at Paleigh. Now if there is any 

 danger whatever from these applications it would be greater with collard 

 than with cabbage, for the collard does not form a head, and consequently 

 every leaf will get some of the poison. The plants at that time were of 

 good size. In treating 460 collards one and one-fourth pounds of the 

 mixture was used, this representing one and one-fourth ounces of paris 

 green. Paris green is about 59 per cent arsenic (the real poison ele- 

 ment). It is considered that one-fourth grain of arsenic is a dangerous 

 dose, hence one and one-fourth ounces contains about 1,390 dangerous 

 doses. This was distributed on 460 plants, or an average of about three 

 dangerous doses was used for each plant. Hence to get enough poison 

 to be a dangerous dose one would have to eat one-third of a plant, even 

 assuming that all of the poison went on the leaves, and assuming that 

 none of it was removed by rains, washing, etc. 



ISTow let us see how it works out in practice. A great deal of the dust 

 never gets on the plants at all, probably one-fourth or one-third of it 

 falls on the ground or is home away in the air. Of the poison that is 

 put on the plant probably over half falls on the large rough outer leaves 

 that are not used for cooking. Of the small amount that does get on the 

 edible parts, the greater portion is removed by wind, or rain, or by the 

 natural growth of the plant. And finally what small fraction of poison 

 there is left is almost completely removed by washing before the vege- 

 table is cooked. We see, therefore, that when used with ordinary judg- 

 ment and caution, the amount of poison that is in the vegetable when 

 it is consumed is so extremely small as to be insignificant. 



