Potential of the fumigant ethanedinitrile to kill the pinewood nematode (Bursaphelenchus xylophilus) and other forest pathogens

A screening test was carried out using ethanedinitrile (EDN) as a candidate fumigant to replace methyl bromide for efficacy against a selection of forest pests, including the pinewood nematodes (Bursaphelenchus xylophilus) and four tree pathogens: Heterobasidion annosum, Geosmithia morbida, Phytophthora ramorum and Ceratocystis fagacearum. Two EDN concentrations were tested: 50 and 100 g/m(3) at two different temperatures and six exposure times. In our tests, EDN was very efficient in killing pathogens in all test parameter combinations, including short exposure times and lower concentration, apart from C. fagacearum surviving short 1 h exposure and G. morbida surviving after 1 and 3 h of exposure. Pinewood nematodes in the small wood blocks were effectively killed at all test parameter combinations. In log sections where deeper nematode infestations were present, nematode survivors at 50 and 100 g/m(3) after 1, 3, and 6 h exposure were observed. This suggests that the fumigant was not efficacious at lower exposure times, while penetrating log sections. Both 50 and 100 g/m(3) dosages were effective after 24 h exposure, indicating that longer retention times are required to effectively kill pine wood nematodes in deeper wood sections. The lower temperature did not affect the efficacy of EDN. This indicates that EDN could successfully eradicate pinewood nematodes in logs over 24 h of exposure, or even less exposure time, at targeted concentrations.