13 



Tohacco in fine powder form dusted lightly on very young- plants 

 serves both as a repellent and as a mulch, or fertilizer. It is claimed 

 by some to deter the striped cucumber beetle; others report that it is 

 not effective for this beetle. 



A successful fumigation or vaporization of a cucumber house 

 infested with the melon aphis was made also in elune, 1906, at Ana- 

 costia, D. C. A different preparation was used, and 66,000 cubic feet 

 of greenhouse space was fumigated, 22 ounces of the liquid, or 1 ounce 

 to 3,000 cubic feet, being employed. The work was under the writer's 

 direction and conducted b}- Mr. I. J. Condit, with the cooperation of 

 Mr. J. W. Bryan, owner of the house. At the end of an hour and 

 fifteen minutes, when the ventilators were opened and the greenhouse 

 aired, the aphides were found dead and d^dng, and the cucumbers 

 were unharmed. Eight evaporators were used in this instance, each 

 holding a little less than 3 ounces of the liquid. It is quite probable 

 that a considerabl}^ smaller amount of the preparation, sa}^ 1 ounce to 

 5,000 cubic feet, with an all-night exposure, would have accomplished 

 the same object. The cost of fumigation is not above $2.50 for a 

 house containing 64,000 cubic feet. 



Caution. — Before fumigating an entire greenhouse with any sub- 

 stance a preliminary test is always advisable to guard against acci- 

 dents and to avoid Avaste of material. In the case of one liquid 

 tobacco fumigant used at Washington, the preliminary test showed 

 that, employed at the strength advised by the manufacturers (/. e., 

 without dilution), it ignited in the evaporating pan instead of vaporiz- 

 ing. This trouble was obviated b}^ diluting the fumigant with half its 

 amount of water, the further precaution being taken of placing a wire 

 gauze beneath the pan and over the flame. In the case of some alcohol 

 lamps used for this purpose the flame is apt to be too strong, espe- 

 cially if placed too near the evaporator. This causes the glass to break. 

 Brass or other metal lamps are therefore preferable. Unless the 

 lamps and wicks are of good quality and fit properly, the alcohol is 

 apt to ooze out around the cork and burn on the sides of the lamp and 

 thus, also, cause breakage. 



As a general rule it is best not to fumigate in hriglit sunlight, and 

 not when delicate foliage or flowers have globules of water on them. 



.SPRAYING METHODS. 



Kerosene emulsion and soap solutions. — The melon aphis could be 

 much more readih^ dealt with if it were not for its unfortunate habit of 

 feeding on the under surface of leaves — which are often badly curled, 

 as shown in figure 1 — and for the further fact that in large fields, par- 

 ticularly late in the season when the leaves are large, the vines grow 

 so closely together, frequentlv becoming interlaced, that spraying by 

 ordinary means is impracticable. Underspraying is an absolute neces- 

 sity, and a sprayer should be used fitted with an upturned elbow and a 



