22 MASS. EXPERIMENT STATION BULLETIN 412 



Semesan Suspension 



Preliminary experiments in New York (5) have indicated that commercial 

 organic mercury compounds gave relatively good control of cabbage maggot but 

 they have been generally discarded for this purpose because of their high cost. 

 In 1943 Semesan was used at the rate of 3 ounces in 10 gallons of water, making a 

 dilution of organic mercury approximately equal to the dilution of corrosive 

 sublimate in the 1-1280 formula. Two applications were made in the same 

 manner and at the same time that corrosive sublimate solution was applied. 

 The treatment gave 87 percent protection and 90 percent of the heads were 

 marketable, but the material cost was two and one-half times greater than that 

 for corrosive sublimate. 



Experiments with Reduced Dosages 



Because of the scarcity of mercury and the need of conserving vital materials 

 during the war emergency, corrosI\'e sublimate and ealomel were used at reduced 

 dosages in 1942 and 1943. The results are shown in Table 12. 



Table 12. Experiments with Reduced Dosages of Mercury Compounds 

 FOR Combating the Cabbage Maggot. Variety, Golden Acre Cabbage. 

 Waltham, Massachusetts, 1942-1943. 



Percent of Plants Showing- 

 No Percent of 

 Material, Dilution, and No Injury Slight Commercial Salable 

 Method of Application Injury Injury Heads 



1942 1943 1942 1943 1942 1943 1942 1943 



Corrosive Sublimate Solution 1-1280 52.2 61.8 47.8 39.2 100.0 100.0 87.8 86.7 



1 oz. in 10 gals, water 

 H cupful per plant 



2 applications 



Corrosive Sublimate Solution 1-1920 78.9 23.3 21.1 68.9 100.0 92.2 90.1 90.0 



1 oz. in IS gals, water 

 Vi cupful per plant 



2 applications 



Corrosive Sublimate Solution 1-2560 — 11.1 — 74.5 — 85.6 — 84.4 



1 oz. in 20 gals, water 

 J4 cupful per plant 



2 applications 



Calomel-Talc Dust, 4 percent Calomel 



Mound Method* 73.3 96.7 24.4 3.3 97.7 100.0 80.7 88.9 



Duster Method** 40.0 — 53.3 — 93.3 — 74.4 — 



Calomel Talc Dust. 2 percent Calomel 



Mound Method* 65.5 85.6 26.7 14.4 92.2 100.0 77.8 80.0 



Duster Method** 10.0 — 44.4 — 54.4 — 72.2 — 



None (Check) 0.0 1.1 12.0 22.2 12.0 23.3 33.3 45.6 



* See page 17 for description of the Mound Method of application. 

 ** See page 16 for description of the Duster Method of application. 



A dilution of corrosive sublimate 1-2560 (1 ounce in 20 gallons of water) pro- 

 tected 85 percent of the plants from commercial injury, but it was significantly 

 less effective than the 1-1280 dilution. A dilution of 1-1920 (1 ounce in 15 gallons 

 of water) was as effective as the standard 1-1 280 dilution in 1942 and gave 92 



