Abstract
Inoculation of an avirulent isolates of the pinewood nematode, Bursaphelenchus xylophilus, is known to induce resistance in Japanese red pine (Pinus densiflora) trees to pine wilt disease caused by virulent isolates of the same nematode species. Mature P. luchuensis trees were examined to determine whether the resistance would also be induced by inoculation of an avirulent isolate in this species or not. The pine trees were pre-inoculated with the avirulent nematode or distilled water, and then inoculated with the virulent nematode. Pre-inoculation with the avirulent nematode decreased the tree mortality after the inoculation with the virulent nematode compared with pre-inoculation with distilled water. The persistence of induced resistance was confirmed by inoculating the surviving sample trees with the virulent nematode again in the following year.
