30 MASS. EXPERIMENT STATION BULLETIN 326 



Naphthalene fumigation may cause injury to plants if certain precautions are 

 not observed, the usual causes being (1) fumigation of intolerant species, (2) 

 failure to provide and maintain favorable atmospheric conditions, and (3) 

 improper adjustment of the vaporizing apparatus. Melted naphthalene should 

 never be allowed to boil nor to closely approach boiling in the vaporizing stove 

 since the fumes given of under these conditions are injurious to plants. The 

 recrystallization of naphthalene vapor from supersaturation or exposure to 

 temperature below 72° F. may also injure plants. After the exposure of the 

 fumigation is completed, the air should be gradually changed without lowering 

 the temperature too rapidly. 



Plant injury following improper naphthalene fumigation usually appears as 

 white areas of dead but not diseased plant tissue, as yellow leaves which soon 

 drop, and as bleached or faded areas on the petals of colored flowers. 



Among the most common greenhouse crops, begonia (Chatelaine type), 

 Boston fern, carnation, and cyclamen are very tolerant; while geranium, lilies, 

 rambler rose, and tomato are usually injured. Most other species and varieties 

 are near the border line between safety and injury and should be fumigated 

 only when pest injury is severe and favorable conditions can be maintained. 

 Greenhouses containing both tolerant and susceptible species of plants should 

 not be fumigated unless the susceptible species are removed. 



Fumigation with naphthalene or similar commercial preparations is a uni- 

 versal treatment for carnations in New England. In experimental plantings 

 naphthalene fumigated carnations produced 14 to 21 percent more marketable 

 flowers per plant than those receiving regular syringing with water. 



Hybrid tea type of roses can be safely fumigated under the most favorable 

 conditions, but the rambler and polyantha type are invariably injured. 



Certain varieties of chrysanthemums are blinded by naphthalene fumigation 

 during the bud forming period but are tolerant to this treatment at other times. 



Cucumber and tomato fruits absorb and retain the odor and taste of naph- 

 thalene for several days after fumigation, making them objectionable to people 

 with a sensitive taste. The tendrils and pistillate flowers of cucumbers may 

 also be injured, and marginal burn on the leaves of both cucumbers and 

 tomatoes occasionally results. 



The initial cost for equipment to fumigate a 60,000 cubic foot greenhouse 

 may vary from $25.25 if the fumigating stoves are purchased to $4.50 if they 

 are homemade. The operating cost including fuel for raising the temperature 

 in cold weather may vary from $5.49 to $1.84 for each treatment depending 

 on the conditions. 



LITERATURE CITED 



1. Back, E. A. Carpet beetles and their control. U. S. Dept. Agr. Farmers' 



Bull. 1346, 13 p., illus. 1923. 

 2. Clothes moths and their control. U. S. Dept. Agr. Farmers' 



Bull. 1353, 29 p., illus. 1923. 

 3. Bishopp, F. C. Fleas and their control. U.S. Dept. Agr. Farmers' 



Bull. 897, 2d revision, 15 p., illus. 1921. 



