18 MASS. EXPERIMENT STATION BULLETIN 412 



LIQUID DRENCHES 



Calomel-Gum Suspension 



Calomel-gum suspension applied at the rate of ]/2 cupful per plant in the field, 

 or 1 gallon to 40 to 50 feet of row or 20 square feet in the seedbed, has been 

 recommended (6, 2). 



At Waltham, in 1940, this material gave perfect protection (100 percent com- 

 mercially uninjured) from the cabbage maggot on Golden Acre cabbage in the 

 field when applied only when the first eggs were found, or at both the first and 

 second application periods (Table 11, footnote). In this experiment, 68 percent 

 of the untreated plants were commercially injured, which is considered a light 

 or moderate infestation for this area. 



Calomel-gum suspension is prepared in two operations. First, dissolve 4 

 ounces of gum arabic in 1 quart of boiling water (powdered gum arabic dissolves 

 more easily than the granular form). Then, grind 4 ounces of calomel with about 

 J^ pint of the gum arabic water solution in a mortar or round bottom bowl with 

 a pestle or the back of a spoon. When a thick uniform paste is formed, add the 

 remainder of the gum arabic solution and stir thoroughly. Ordinarily, each 

 quart of this mixture is diluted to make 10 gallons of liquid for application, but 

 if the infestation is light 1 quart of this mixture can be diluted to make 40 gallons. 



Glasgow (6) states that in New York calomel-gum mixtures are prepared 

 and handled by the trade, but no commercial sources of calomel-gum arabic are 

 known m Massachusetts. 



In spite of its excellent protection, the complicated method of home preparation 

 makes this treatment impractical for many growers and it is recommended only 

 if other materials are unavailable or other treatments have been found unsatis- 

 factory. 



Corrosive Sublimate Solution 



For about 20 years, applications of corrosive sublimate solution have been the 

 standard treatment for the control of the cabbage maggot, and the use of this 

 solution has been widely recommended throughout the area where this pest is 

 destructive (7). 



Corrosive sublimate, also known as bichloride of mercury and mercuric bi- 

 chloride, is prepared in the form of a powder, granular crystals, or pressed tablets. 

 The powder and crystals are usually sold by the pound or fraction thereof, and 

 the tablets in packages of 25, 50, or 100, each tablet usually weighing 7.3 grains. 

 Corrosive sublimate is white but, in the tablet form especially, it is frequently 

 colored blue to emphasize that it is poisonous and should be handled accordingly'. 



Corrosive sublimate corrodes metals and should be stored only in wood, glass, 

 or porcelain containers. Likewise, whenever possible, the solution should be 

 made in non-metallic containers. It should never be allowed to stand in contact 

 with metal. The use of this solution in metal pumps and pipes is not advised, 

 but if it is so used the metal equipment should be thoroughly flushed with clean 

 water immediately afterwards. 



Preparation of the Solution. — Corrosive sublimate solution is prepared by 

 dissolving corrosive sublimate powder, crystals, or tablets in water. The chemical 



