The sensitivity to the different oils was classified by the diameter of the inhibition halos as follows: not sensitive () for diameter less than 8 mm; sensitive (+) for diameter 9–14 mm; very sensitive (++) for diameter 15–19 mm and extremely sensitive (+++) for diameter larger than 20 mm (Ponce, Fritz, Del Valle, & Roura, 2003). Each assay was performed by duplication on two separate experimental runs.