PLANT ENEMIES 



49 



.SoLANUM CApsiCASiRUM (JERUSALEM Cherev). — See page IS5 



lo. Hydrocyanic Acid Gas. Fatally poisonous. For green- 

 house use: I ounce potassium cyanide (98 per cent, pure), i ounce 

 sulphuric acid, 3 ounces water. Use an earthen dish, pour in water 

 and add the acid to it. When all is ready so that the operator can 

 make a hasty exit, drop in the potassium cyanide which is best 

 placed in a paper. Useful for white fly and most greenhouse in- 

 sects, except red spider and nematode worms. Fumigate on dry, 

 dark nights when it is still, not windy; close ventilators and leave 

 all night. Place danger signs on all doors. The above proportions 

 are used for 3,000 cubic feet of air space on Chrysanthemums, 

 Cinerarias, Azaleas, bulbs, Carnations and other common plants. 

 Ferns and Roses are susceptible to injury; use weaker and then 

 increase strength if there is no injury. 



