JU Makch. li»l!>.| Apple CuH me III V'lrfona. 145 



APPLE CULTURE IN VICTORIA. 



(Continued from J)aye ol .) 



Bij J. FarrcII, Orchard Supervisor. 

 Sak Jose Scale (Aspidiotus perniciosus) — continued. 



Good results Iiave been obtained from crude petroleum emulsion, 

 1 ill 8 and 1 in 10, against apple bark scale, woolly aphis, and red 

 spider, and being much cheaper than red oil, it is a popular spray 

 for this purpose. The freedom Avith which the emulsified condition of 

 this oil is formed and maintained also assists in popularizing this 

 spray. Its effectiveness against San Jose scale, however, is hardly 

 conqiarable with that of good red spraying oil. 



Although lime-sulphur is essentially a fungicide, its effectiveness in 

 destroying red mite, aphis, and scale insects is favorably spoken of by 

 persons who have used it, but the writer's experience is that oil sprays 

 are much better. At the same time, Mr. G. M. Fletcher, Orchard 

 Sui)ervisor, in charge of the Goulburn Valley district, reports that 

 satisfactory results followed the treatment of San Jose scale with lime- 

 sulphnr during the last spraying season. 



Hydrocyanic Gas Treatment of Scale Insects. 



When the eradication of San Jose scale or other like pest from an 

 orchard or from a district is being contemplated, it should be recog- 

 nised that hydrocyanic acid gas is the most effective and reliable agent 

 at present known by which this object may be achieved. This gas 

 being generated from sulphuric acid, cyanide of potassium, and water, 

 is most destructive to insects within the range of its influence. 



F'umigation as a means of destroying citrus pests has been fairly 

 extensively employed, but the gas treatment of those infesting deciduous 

 trees is limited. The tree to be fumigated is enclosed in a tent or 

 sheet made of strong unbleached calico or other suitable material. Then 

 the approximate cubical content of the tent, which is usually irregular 

 in .shape, is found by multiplying its mean height by the square of its 

 mean diameter. When fumigating a number of trees of one variety, 

 the same age, and growing under similar conditions, it is only necessary to 

 take the measurements of one, and adopt the cubical content calculated 

 as described as a standard, for under the system of modern i^runing 

 th(> trees will be uniform in size and shape. When the covering is put 

 over the tree, earth should be placed on the bottom edge of the tent 

 material, so as to prevent the escape of gas during, the process of 

 fumigation. 



The amounts and proportions of gas-producing chemicals required 

 for any given space may vary somewhat, but these can be regulated 

 according to circumstances. One fluid ounce of sulphuric acid, 3 fluid 

 ounces of water, and 1 ounce of cyanide of potassium may, however, be 

 regarded as a fair approximation of the quantities necessary to suffi- 

 ciently pollute each 150 cubic feet of air space and destroy scale insects 

 M^thin a period of 45 miiiutes. A glazed earthenware vessel is used 

 in which to generate the gas. The water is first placed in this, then the 

 sulphuric acid is jioured in and the vessel placed under the tent. A 

 small opening is provided under the tent through which the hand is 

 admitt<^d, and the cyanide is carefully dropped into the acid and water 



