Everybody knows 55 C x 5 x 3. A compost pile has to reach 55º for 5 turns with a total of 3 days at temperature between turns. Those are the requirements to reach pathogen kill to make sure that the compost is Class A and is safe for general use. In our world that is pretty much the ‘apple a day’ equivalent. Recently Tania Gheseger from Metro Vancouver asked me for papers that show that that same 55 x 5 x 3 kills weed seeds too. My first reaction was to tell her that ‘everybody knows that’, thinking that it was part of the general wisdom rather than a conclusion from peer reviewed studies.