Strategies to eradicate Ailanthus altissima (Mill.) Swingle in a forested area

Ailanthus altissima is a tree belonging to the Simaroubaceae family. Its high invasiveness potential may have a strong impact on the biodiversity in non-native areas. The aim of this study was to test practical and effective chemical methods to eradicate spot infestations of A. altissima in a forested area. The study, started in summer 2016, was conducted in a forest ecosystem located in the municipality of Almese, North-west Italy. Two representative infestation spots (A and B) have been individuated and A. altissima plants counted and labeled. A total of 76 (A) and 82 plants (B) were considered. The herbicides used were glyphosate (as 540 g/L formulated product, diluted at 50\% v/v) and a mixture of aminopyralid+fluroxipyr (144.1 g/L+35.5 g/L; diluted at 10\% v/v). Two application techniques were compared: basal bark application (BB) and stem injection (SI). BB technique was applied on plants with a circumference lower than 12 cm moistening the first 0.5 m of plant stem by using a hand pressure sprayer. SI technique has been applied on plants with circumference higher than 12 cm. Herbicide was injected into plant stem through holes previously made with a battery drill. The number of holes varied in accordance to the circumference size (2 holes for circ. 12 to 20 cm, 4 holes for circ. 21 to 40 cm). One year after treatment, about 70\% of plants treated with aminopyralid+fluroxipyr showed living sprouts, with negligible differences among the application technique used. Only 30\% of plants treated with glyphosate showed living sprouts, the majority of them treated with BB technique.