8 CIRCULAR 411, U. S. DEPARTMENT OF AGRICULTURE 





Figure 1. — After cabbage has reached the stage of growth shown here, arsenical treatments should not be 

 applied, as harmful residues are likely to remain on the cabbage at harvest time. 



treatment and trimmed to conform to U. S. grade No. 1— except in 

 one experiment in which the entire leaf growth was included for 

 analysis, the stalks being cut just below the bottom leaf. The 

 studies were conducted under various conditions of rainfall, tem- 

 perature, and soil, and with three plant varieties. 



This study showed that, with intervals up to 30 days from the last 

 arsenical application to marketing, cabbage may retain arsenical 

 residues exceeding the legal tolerance of 0.01 grain of arsenic trioxide 

 per pound of marketable product. The loose leaves surrounding the 

 compact head carry the principal portion of these residues. The 

 variety of cabbage and the quantity of rainfall also affect the residues 

 on the harvested product. Excessive residues were found in these 

 tests in nearly all instances where the samples were taken within 10 

 days after the last application of the arsenicals was made, in about 

 30 percent of the samples examined after about 20 days, but in less 

 than 10 percent of the samples taken after 24 to 30 days. For 

 periods of time exceeding 30 days no excessive residues were found 

 during the course of these tests. 



According to the data obtained in this study, it appears to be 

 unsafe to apply arsenicals on cabbage after foliage becomes exposed 

 which will be a part of the marketed product. In the instance of 

 crops which will be marketed as U. S. grade No. 1, no applications 

 should be made after the heads begin to form. 



U. S. GOVERNMENT PRINTING OI'FICE: 1937 



For sale by the. Superintendent of Documents, Washington, D. C. - - - - - Trice 5 cents 



