Control of giant reed Arundo donax on Vila Franca do Campo Islet, Azores, Portugal

The non-native, invasive giant reed Arundo donaxcovers an estimated 30% of Vila Franca do Campo Islet (Azores). It blocks the entrance of Cory's shearwater Calonetris diomedea borealis nest burrows and out-competes threatened Azorean endemic flora. Three A. donax control methods were tested in 90, 1m2 plots, and cost-effectiveness of each determined using a Simple Additive Weighting Model. The most effective control method was cutting and removal of reed stems followed by two glyphosate-based foliar herbicide applications (one in May and another in late October i.e. corresponding to before and after the Cory's shearwater breeding cycle). After one year, 92% of giant reed was eradicated at an estimated cost of €8,000 per hectare.