THE CABBAGE MAGGOT 19 



dissolves more quickly in hot water, and dissolving it in a small amount of hot 

 water before diluting for application is often desirable. Because its solubility 

 is limited, each ounce of the chemical should be dissolved in 1 pint or more of 

 water. Otherwise, a saturated solution is formed and a part of the corrosive 

 sublimate does not dissolve. 



Dilution. — The standard dilution of corrosive sublimate in water for com- 

 bating the cabbage maggot is 1-1280 or 1 ounce in 10 gallons. However, as noted 

 in the discussion of seedbed treatment, this chemical has been used at dilutions 

 ranging from 1-1000 to 1-2500 with generally good results, and the 1-1280 dilution 

 was recommended because it was consistently effective under average conditions 

 rather than because it was the minimum effective dilution. Furthermore, a 

 1-1920 dilution has frequently been used effectively on cauliflower to avoid 

 injury from the stronger solution. 



In experiments at Waltham in 1942 and 1943, a 1-1920 dilution gave very 

 good protection on cabbage when carefully- applied, and there was no significant 

 difiference in the effectivness of the 1-1920 dilution and the 1-1280 dilution. 

 These results are shown in Table 12, and they are discussed under "Reduced 

 Dosages." 



From these results, as well as from personal observations, it is concluded that 

 a 1-19?0 dilution can be used effectively undeT favorable conditions and it is 

 recommended when the chemical is scarce and the solution can be applied care- 

 fully. 



In home gardens or where only a few plants are treated, corrosive sublimate 

 solution may be prepared by dissolving the tablets. The usual corrosive sub- 

 limate tablet prepared for medicinal use weighs 7.3 grains and when dissolved 

 in 1 pint of water makes a 1-1000 solution. Six tablets dissolved in 1 gallon of 

 water makes approximately a 1-1300 solution, which is satisfactory to use for 

 combating the cabbage maggot. 



Method of Application. — Sufficient solution should be applied around the 

 roots of each plant to thoroughly wet the soil at least 1 inch deep. Approxi- 

 mately 4 ounces or }/2 cupful is an average application, and this amount was used 

 in all of the experiments at Waltham. 



On small plantings and on large plantings when sufficient labor is available, 

 the solution can be applied by dipping it from a pail (Figure 5-A). A suitable 

 dipper is easily made by attaching a wire handle to a glass jar holding J-2 cupful. 

 Knapsack sprayers with the nozzle removed and the flow of liquid regulated by 

 the spring shut-off on the rod handle, and an ordinary watering pot from which 

 the sprinkler head has been removed, have both been used. A few large growers 

 have used a power spray machine operated at low" pressure, but this is not recom- 

 mended. Barrels or tanks mounted on low wagons with the solution flowing by 

 gravity through one or more short lengths of hose which the operator squeezes 

 by hand to regulate the flow have been used successfully, and at least one large 

 cabbage grower adapted this idea to a tractor-drawn mechanical transplanter 

 from which operators riding close to the ground treated two rows of plants at 

 a time. 



In much of the experimental work at Waltham, an applicator designed and 

 made for treating cabbage plants was used. This apparatus, which is shown in 



