368 Journal of Agriculture, Victoria. [ioth June, 1912. 



The work was carried out in July. One ounce each of cyanide and 

 acid to 120 cubic feet was used, i.e., about a quarter strona;er than that 

 used on evergreen trees. The scale was completely stamped out. It is 

 now nearly three years since the trees were treated, and, although a careful 

 inspection of the orchard where the outbreak occurred has been frequently 

 made, no trace of the scale could be found. 



Fumigation for Woolly Aphis was also tried in Mr. Finger's orchard 

 in May, 1909. A charge of the same strength as that used for citrus trees 

 was given. On examining the trees a month later, live aphis were found 

 in the knots and excrescences, though examination immediately after treat- 

 ment revealed no living aphis. These were, no doubt, protected in the 

 interstices of the bark from the action of the gas. 



Fumigation Outfit. 



Sheets, either octagonal or square, made of strong closely woven- 

 unbleachtd calico, are recommended. The octagonal sheets require less 

 material to cover a tree of a given- size than a square sheet, but there is 

 more trouble in making them up, and, consequently, the square sheets are 

 more favored. A tree 13 feet high can be covered by a sheet 36 feet 

 square, and one n feet high by a 30-ft. square sheet. It requires 

 72 yards of calico, double width, fo make the form.er, and 50 yards the 

 latter. The cost of the calico is about is. 3d. per yard. Before making 

 up the sheets, growers should measure the height of their trees, and the 

 height multiplied by 2| gives, roughly, the size of the sheets required. 



Loops of rope or rings should be attached to two sides of the sheet, 

 about 15 feet apart, and equal distances from the corners. These are 

 required in which to insert the poles when placing the sheet over the tree. 



Chemicals Required. 

 Cyanide of potassium (the best quality) and sulphuric acid, are the 

 chemicals used for generating the gas. Both are sold by avoirdupois 

 weight, but the quantities given in the fumigation table are ounces avoir- 

 dupois and fluid ounces respectively. 



This has to be taken into account when ordering the chemicals. There 

 are but 9 fluid ounces of sulphuric acid in i lb- avoirdupois, so, in order- 

 ing, it is required to get 16 lbs. of acid for every 9 lbs. of cyanide. 

 The cost of the cyanide is 9d. to lod. per lb., and sulphuric acid i|d. per 

 lb. The cost of a charge for a tree 11 feet high by 11 feet in diameter 

 is about 4d. 



A pair of scales is required to weigh the cyanide, and a measuring 

 glass for the sulphuric acid and water. The scales should be accurate 

 and in good order. 



Placing Sheets over Trees, Charging, etc. 



Two light strong poles 12 to 15 feet long, according to the height of 

 the trees, are required. These should be pointed at one end, and have 

 a fork at the other. 



The forked end is wanted to insert in the loop or ring attached to the 

 sheet, and the pointed end prevents the poles from slipping on the ground. 



Two men can with the.se easily rai.se the sheet and draw it over the tree. 

 The operators should, if there is a breeze, work towards it, when the 



