A strong edge colouring of a graph G is a proper edge colouring such that every path of length 3 uses three colours. In this paper, we prove that every subcubic graph with maximum average degree strictly less than 1 (resp. 27/11, 13/5, 36/13) can be strong edge coloured with six (resp. seven, eight, nine) colours. (C) 2011 Elsevier B.V. All rights reserved.