GREENHOUSE AND COLD FRAME FUMIGATION 133 



A plain wooden box, such as is shown in Figs. 49 

 and 50, or even a small Kmory fumigator, as seen in 

 Figs. 33 or 36, will be found very useful to florists 

 and gardeners in any greenhouse or nursery grounds. 

 This box can be used for the fumigation of small 

 shrubs and plants on lawns, in gardens, and various 

 other places where it is desirable to fumigate them 

 without taking them up. The box may be used in 

 the daytime if the work is done in a cool place. 

 Some florists and nurserymen use small boxes in their 

 packing-houses and cellars where the temperature is 

 constant. Care must be taken, however, where the 

 gas is generated and released in such places, to see 

 that proper ventilation is secured to carry away the 

 poisonous fumes when released from the box. Nurs- 

 erymen handling ornamental plants can use their 

 fumigating houses for the treatment of various shrubs. 

 Some florists have found that a small greenhouse con- 

 taining 1,000 feet or less is more reliable than a box. 

 There is less danger of injury to the foliage under 

 such conditions. 



Experience with various plants. Although a large 

 number of greenhouse plants have been fumigated, 

 there is yet room for much careful experimental work. 

 The following list of plants, given by Dr. Woods, 

 have been fumigated. 



Ferns. For Davallia mooreana, infested with a 

 scale insect {Chionaspis sp.), 0.075 gramme of 98 per 

 cent, potassium cyanide should be used for each cubic 

 foot of space to be fumigated, not deducting the space 

 occupied by the plants. length of exposure, twenty 

 minutes. 



