Ethylene production in living and dying stems (survived and killed, respectively) of Quercus serrata trees attacked by ambrosia beetles, Platypus quercivorus, was compared to production in non-attacked stems. Attack by the beetles is associated with infection by the symbiotic fungus Raffaelea quercivora. High levels of ethylene production occurred in stem segments of a survived tree compared with those in non-attacked or killed trees. Attacks were generally concentrated at the stem bases of both survived and killed trees. Earlywood vessels occluded with tyloses significantly increased in the survived tree compared with the non-attacked tree. Current-year wood located close to the cambial region had high ethylene production ability, unlike the inner sapwood or intermediate wood in the non-attacked tree. Such ethylene production was significantly enhanced in the survived tree, which had many fungal hyphae in current-year vessels. The increase in ethylene in current-year wood may be related to the mechanism of induced resistance to pathogen infection in oak trees.
Oxytetracycline (OTC) concentration was measured and phytoplasma was detected from the leaves of test trees, Elaeocarpus sylvestris var. ellipticus infected with elaeocarpus yellows, after the trunk injection with “Mycoshield” solution (1000 ml, containing 0.34 g OTC) or OTC hydrochloride solution (100 ml, containing 3.52 g OTC). The residual period of OTC was about 4 to 8 months after trunk injection in any test trees. Phytoplasma was not eliminated by the injection.