Glyphosate treatments for weed control affect early stages of root colonization by Tuber melanosporum but not secondary colonization

The following application regimes were tested: (i) no treatment, (ii) one application in May 2017 and (iii) three applications each 45 days beginning from May 2017 and finishing in August 2017. In each application, the commercial glyphosate–based herbicide Roundup Ultra Plus® (360 g glyphosate L−1) was sprayed on the grass at an application rate of 1.25 mL m−2 of commercial product (0.45 mg glyphosate m−2), in an aqueous solution (2.8% v/v).