Green’s Dictionary of Slang

poisoner n.

(Aus./N.Z.) a cook, esp. one serving a team of sheep shearers; thus poison v., to cook.

[Aus]Worker (Brisbane) 4 Sept. 8/4: A decent cook he calls his ‘doc,’ and makes of him a god, / A bad one is a ‘poisoner,’ a ‘slushie’ and a ‘sod.’.
[Aus]Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 7–8: At different times [...] there have appeared accounts of serious tragedies through the use by mistake of poisons for baking powder [...] Poison on stations carelessly left about kitchens in tins, jars or bottles falling into the cooks [sic] hands have no doubt first earned the cooks the name of poisoner.
[Aus]E.S. Sorenson ‘Bush Cooks’ in Life in the Aus. Backblocks 88: On the other hand, if he is rationed out, as at many stations, and allowed none of the extras that help, as bushmen say, to top off a meal, the table naturally suffers, and the best name the men can find for him is ‘poisoner.’ [Ibid.] 93: A rouseabout went on cooking. He proved the greatest poisoner that ever handled flour; but he had a civil tongue [...] and if his bill of fare was monotonous, there was no lack of variety in his excuses.
[NZ] (ref. to 1890–1910) L.G.D. Acland Early Canterbury Runs (1951) 390: Poisoner – [...] Slang name for a cook.
Walkabout 8 80/2: The ‘poisoner’ was often a middle-aged man, and generally an accomplished one [...] It was an interesting sight to watch a practised old bush cook deftly wielding his long-handled shovel in the embers.
[Aus]B. Wannan Fair Go, Spinner 126: ‘Crippen’, ‘poisoner’, ‘bait-layer’, are other terms for a bush cook.
W.N. Scott Complete Bk Aus. Folk Lore 381: Some of them were a law unto themselves, some of them were slightly mad, some of them could cook very well, some of them were ‘poisoners’. [...] Every bush cook was supposed to be ready to fight for his cooking.