Dec. 2, 1920.] Agricultural Gazette of N.S.W. 893 



Gas (Arsenious chloride). 



All liquid poisons (and to a greater extent those used in the solid or even 

 deliquescent state) have the drawback that, whether applied in a finely 

 divided state (as a spray) or without much propelling force, their action is 

 usually more or less concentrated on the face on which the liquid is applied. 

 In other words, only those plants are affected which receive the impact 

 of the spray. 



All sorts of liquids (usually solutions in water) have been tried, and valu- 

 able data have been secured as to their effectiveness and limitations. It 

 was then interesting to find a new direction for research, that is, the aid 

 of a gas called in — an all-pervading form of matter which would envelop 

 the pear all round, would surround it in fact; would turn round the corners 

 and let no portion, no face, of the pear escape contact with the poison. I 

 refer to the use of arsenious chloride by an American chemist, Mr. A. C. 

 Roberts, who operated chiefly in Queensland. This substance is a liquid 

 (twice as heavy as water), but no water is tised. By air pressure in the 

 use of an atomizer, this liquid is converted into a gas, but this apparatus 

 is chiefly used for scattered pear. When the pear is dense and over large 

 areas a machine something like a tar-boiler is used and the gas evolved 

 attacks acres of pear in a day. In the use of this apparatus the direction 

 of the wind is studied, not only so that the gas may be guided where desired, 

 but also to protect the operator. By the use of gas, gullies and broken 

 country generally bearing pear, which cannot be tackled by the ordinary 

 spraying apparatus, are dealt with. The method is still the subject of 

 experiment. 



High Pressure Steam. 



Mr. Will A. Dixon, in the newspapers of 26th February, 1904, advocated 

 destruction of pear by high pressure steam. 



QuEENLESs Colonies. 



In any case where a colony becomes queenless, and no eggs nor young Jarvai 

 are present in the combs to give the colony a chance to raise another queen, 

 such a colony will certainly die out, even if ample stores are available, 

 because no young bees can be raised to take the place of the old bees. It 

 occasionally happens that a queen dies during winter when no brood is iu 

 the hive, and in this case the bees have no chance of raising another queen 

 If a queen dies during a time when progressive brood-raising is going on, 

 the bees usually raise another queen from the very young worker larv:e. It 

 happens in some cases that the young queen gets lost when taking her 

 mating flight, thus leaving the colony queenless and without young brood 

 from which another queen can be raised. The only chance in sucli cases is, 

 in season, to introduce to the queenless colony a frame of brood containing 

 eggs or very young larvfe, or to introduce a queen before the colony gets too 

 ^veak. — W. A. Goodacre, Senior Apiary Inspector. 



