Thinning is a prerequisite in worldwide fruit production. The question arose as to its contribution to the carbon footprint in different production schemes. Carbon footprinting of thinning in fruit orchards is based on fossil fuel consumption, converted into greenhouse gas emission (GHG) and expressed as CO 2 equivalents, which comprises carbon dioxide (CO 2; factor 1), methane (CH 4; factor 25) and nitrous oxides (N 2O; factor 298), according to PAS 2050: Oct 2011 and PAS 2050-1 (hort). Flower thinning with ATS foliar nitrogen fertiliser emitted 25-37 kg CO 2e/ha per treatment (without associated N 2O emissions), while fruitlet thinning with 6-BA emitted ca. 13 kg CO 2e/ha, Brevis 18.5 (single application) or 34 (double application) kg CO 2e/ha and lime sulfur in organic orchards 27-42 kg CO 2e/ha. Mechanical thinning with the Bonner machine at 6 km/h at 360 rpm produced 27.9 kg CO 2e/ha emissions, while manual fruitlet thinning after June drop had a carbon footprint of only 3.1 kg CO 2e/ha, since manual labour does not utilize fossil fuel.
