126 VEGETABLE FORCING 



return. Special nozzles have been devised for this purpose. 



Soap solutions are often employed, but there is a dif- 

 ference of opinion regarding their value. One ounce of 

 laundry soap to five gallons of water is an approved 

 formula for this purpose. Whale oil soap, two pounds to 

 50 gallons of water, is also used. 



Sulphur in various forms is used extensively in com- 

 bating red spiders. Dry sulphur may be applied to the 

 plants with a dust gun. Sulphur as a liquid spray has not 

 been very effective against the red spider on cucumbers. 

 Sulphur is sometimes painted on hot greenhouse pipes, 

 where it slowly volatilizes, thus becoming a fumigant. 

 For many years florists considered this practice of value 

 in suppressing red spiders. Experiments made by Ewing 

 show the futility of it. He says: "Eleven days of this 

 treatment had not the slightest effect upon the spider 

 mites. The practice may be considered as foolish and use- 

 less as the equally old and time-honored custom of throw- 

 ing handfuls of powdered sulphur in the crotches of trees 

 in order to eradicate mites in an orchard." 



Tobacco sprays are employed by many greenhouse 

 growers. The Ohio Experiment Station obtained excel- 

 lent results in the greenhouse by using one-half pint of 

 a proprietary tobacco extract, two quarts of lime sulphur 

 and 25 gallons of water. 



Oil emulsions are effective sprays against the red 

 spider. Ewing recommends two gallons of distillate, four 

 pounds of whale oil soap and 100 gallons of water. Dis- 

 solve the soap in a few gallons of hot water by heating. 

 Add the oil and agitate in the usual way with a force 

 pump until the solution is well emulsified, and then dilute 

 to 100 gallons. 



Miscellaneous pests, such as white ants, white grubs, 

 sow bugs, snails, millipedes, wireworms and cutworms, 

 which may cause injury to greenhouse vegetable crops, 

 may be eradicated by thorough soil steam sterilization 

 before the crops are started in the permanent beds. 



