22 



Other planls. — Other plants on which the gas has been tried on a small scale indi- 

 cate that it may probably have quite a wide range of usefulness.' 



Roses. — "Perle des jardins," "Mermet," and "Bride." The young growth on 

 roses is particularly sensitive and has been more or less injured in all our experiments. 



Carnaiions. — Scott, Garfield, Meteor, and McGowan will stand one-tenth of a gram 

 of 98 per cent cyanide per cubic foot of space for 15 minutes without material injury. 

 This will kill about 90 per cent of the plant-lice, but will not kill thrips. The use 

 of the gas for carnations needs to be more carefully investigated before it is recom- 

 mended. The same is true of chrysanthemums, on which it has been tried with 

 only partial success, the young growth being very sensitive. 



Grapes under glass. — The gas has been used with success in New Zealand - for mealy 

 bugs {Dactylopius adonidum L.) at the rate of one-third of an ounce 98 percent C3'a- 

 nide to 100 cubic feet. This is equivalent to nine-hundredths gram per cubic foot. 

 The gas is liberated after dark and left in till next morning, when thorough ventila- 

 tion is given. It largely escapes, however, during the night. The treatment is said 

 not to injure the plants in the least. 



Tomatoes. — Dr. Jabez Fisher, in "American Gardening" (Oct. 29, 1898), reports 

 using the gas for "white fly" {Aleyrodes sp.) on tomatoes. The gas from one ounce 

 of pure cyanide of potassium for each 1,000 cubic feet left in the house over night 

 killed all the insects without injury to the plants. This method has not yet proved 

 successful with us in any case, but it should nevertheless receive careful trial by 

 other exj^erimenters. 



CUBIC CONTENTS OF THE HOUSE.^ 



In all cases where fumigation with this gas is to be followed it is necessary to first 

 determine accurately the cubic contents of each house. The determination of the 

 cubic contents of the house, while in itself a comparatively simple problem, has, in 

 the eyes of many growers, difficulties which they are not willing to undertake. The 

 cubic contents can be determined by a comparatively simple mathematical calcula- 

 tion, but perhaps the easiest way is by a method recently described by the writer in 

 the Florists' Exchange [Vol. II, no. 5]. This method involves nothing more diffi- 

 cult than the mere counting of a number of squai-es, and from an examination of the 

 accompanying illustration [fig. 5] the simplicity of the method will become apparent. 

 Procure from a stationery store or art supply store some cross-section paper, such as 

 represented in the figure. In this particular case squares of three sizes are shown, 

 the largest being one-half inch, the next one-fourth inch, and the smallest one- 

 sixteenth inch square. The one-fourth inch squares may represent feet. Now 

 determine the dimensions of the house — that is, the length, width, height to ridge, 

 and height on sides, and make a sketch as shown, each square or one-fourth inch 

 representing 1 square foot. This particular house, it will be seen, is 18 feet (18 

 squares) wide, 12 feet to the ridge, 6^ feet high at the back, and ih feet high in front. 



The ridge stands 5 feet from the back wall, as shown in the sketch. After the 

 lines are drawn, simply count the squares inclosed, and the number of squares will 

 be the number of square feet. The parts of squares, that is, where a line divides a 

 square, can be easily determined by counting the smallest squares, or by the eye, 

 and by adding these fractions of squares together the number of whole squares may 

 be readily found. After the number of square feet is obtained it is only necessary 



1 The gas has been used on the following plants at the rate of one-tenth gram of cyanide per cubic 

 foot of space for twenty minutes without injury. Further experiment, however, is necessary before 

 the treatment can be recommended for these: Alocasia Macrorhiza raricgala; Antliurium crijstallinum; 

 Areca liitescens; Aralia filicifulia; Adiantum cuneatum; Adiantian Bullii; Campylohotrys rejulgeni<; 

 Cissus discolor; Crotons (in variety) ; Cichoriuni intybus; Diffcnbachia Lenmanii; Ficus elastica; Fuchsias 

 (in variety); Jacaranda mimosscjolia; Marantas (in variety); Kyniplia'a candid issima, and odorata 

 rosea; Pontederia crassipes; Pandanus vcitchii; Plirynium variegatnm; PhyUotxnium Lindenii; Panax 

 Victorioe; Stenanthium Lindenii. 



« Fourth Report, Dept. of Agr., New Zealand. 1896. Pp. 141-14;;. 



a The method described is quoted from B.T.Galloway's Book on Violet Culture. 



