22 



MASS. EXPERIMENT STATION BULLETIN 361 



Fumigation with Burning Sulfur 



Past recommendations show a lack of uniformity in dosage recommendations 

 for burning sulfur between crops in greenhouses. Most of the recommendations 

 are based on the dosage necessary to accomplish destruction of the red spider 

 mite (Table 11). 



Table 11. — Quantity of Sulfur to 1,000 cubic feet Recommended for 

 Burning in the Disinfestation of Greenhouses 



Authority 



Quantity Period 



Remarks 



Makemson (26) 5 pounds 24 hours 



Williams (54) 2 pounds 



Small (44, 46) 1 pound 



Van der Meer (52) 10 ounces 2 hours 



Van der Meer (52) 2>^ ounces K hour 



Read (36) 1 pound 



Haseman and Jones (20) 30 pounds 

 Compton (12) 3-5 pounds 



1 percent concentration of SOg 

 Distributed in 5 heaps 

 In commercial practice 

 In laboratory chamber 



For greenhouse pests in general 

 For greenhouse insects 



Small (43, 44, 46) noted that several heaps of burning sulfur gave better results 

 than the same quantity of sulfur in one heap, and that rapid generation of the 

 gas was essential to an effective destruction of the spores of the tomato leaf mold 

 fungus. Judging from recommendations in popular articles, the ratio of 1 pound 

 of sulfur to 1 ,000 cubic feet of greenhouse space has received most general accept- 

 ance. It is generally conceded that, even at this dosage, some eggs and mites 

 survive. This fact has led to the practice of burning even greater amounts of 

 sulfur to 1,000 cubic feet. 



The burning of excessive quantities of sulfur in greenhouses between plantings 

 is harmful to iron frames and piping, wires, metal gutters, and paint. The film of 

 acid formed on the interior surfaces softens the paint and causes it to shed. The 

 soluble residues gathering in water and subsequently dripping upon the plants 

 in the beds have been the cause of much plant injury. These effects from the 

 burning of sulfur have been the chief factor in discouraging the practice for 

 cleaning up pests between plantings. 



Read and Orchard (35) and Read (36) found that zinc sulfate was formed from 

 the action of sulfuric acid on white zinc paints and galvanized wire, and that 1 

 pound of sulfur to 1,000 cubic feet resulted in considerable drip damage. No 

 damage resulted where surfaces were protected with lead or barium base paints. 

 More recently Kadow et al. (25) reported an instance of injury to tomatoes from 

 drip from zinc galvanized pipes and wires in a greenhouse where sulfur had been 

 burned as a clean-up measure, but the exact dosage was not stated. In Massa- 

 chusetts greenhouses injuries to plants from drippings from iron pipes, zinc-coated 

 wires and metal, and from surfaces covered with zinc paints following the burning 

 of large amounts of sulfur have been frequent. A study of the problem, therefore, 

 seemed desirable. 



