80 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



FUMIGATION OF NURSEBY STOCK * 



By Professor W. G. Johnson, U.S.A., formerly State Entomologist of 

 Maryland, now Associate-Editor of the American Agriculturist, 



A GAS-TIGHT house or room is the first thing necessary for the fumiga- 

 tion of nursery stock. The efficacy of the treatment depends upon 

 keeping in all the death-dealing gas. The size and location of the build- 

 ing depend largely upon the amount of stock grown, and upon the 

 character of the buildings near the packing sheds and " heeling-in 

 grounds." In some cases a separate building is not necessary, as a corner 

 of a shed or other inclosure can be cheaply converted into a suitable 

 fumigating house. It would be useless to discuss in this article the 

 reasons that have made it necessary to fumigate nursery stock for the 

 destruction of various insect pests. As a matter of fact, most extensive 

 fruit-growers hesitate about purchasing trees until such stock has a clean 

 bill of health, and in many instances it is stipulated in the contract that 

 they shall be fumigated with hydrocyanic acid gas. The cost of fumiga- 

 tion per 1,000 trees is less than lOd., including labour, chemicals, and 

 extra handling. As a business proposition, many nurserymen are con- 

 sidering this, and advertise that they fumigate all nursery stock. 



Construction of the House. 



A room suitable for fumigating purposes will admit of no careless 

 workmanship. Doors, ventilators, and windows should be tightly fitted. 

 The timber should be carefully selected, especially the flooring used for 

 lining. It should be as free as possible from knots. One of the largest 

 fumigating houses known to me is 36 x 16 x 8 ft., with a roof pitch of 2 ft., 



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Fig. 15. — Outline of Model Fumigating House. 



and is divided into two large rooms 15x14x7 ft., and two smaller rooms 

 4 X 5 X 7 ft. The flues, for ventilating purposes, lead out at the top of 

 the roof and are ^o arranged they can be opened from the outside. There 

 is also a small door, 2J x3 ft.^ on the opposite side of each room, which, 

 when opened, insures quick ventilation. 



First, a strong frame should be built and covered outside with 1 J x 

 12 in. Va. pine boards, and J x 4 in. batten. The interior, including the 



* Reprinted by permission from the American Agriculturist. 



