Korea Forest Research Institute, Republic of Korea.
Phytopathology. 2013 Jun;103(6):565-74. doi: 10.1094/PHYTO-10-12-0272-R.
Hundreds of cankers caused by Ceratocystis smalleyi are associated with hickory bark beetle-attacked bitternut hickory exhibiting rapid crown decline in the north-central and northeastern United States. Discolored sapwood colonized by the fungus commonly underlies the cankers. Field studies were conducted to test the hypothesis that C. smalleyi infections cause vascular system dysfunction in infected trees. Fifty C. smalleyi inoculations made at 1.8 to 3.8 m in height on stems of healthy bitternut hickory trees (13 to 28 cm in diameter at 1.4 m in height) resulted in extensive canker formation and sapwood discoloration 12 to 14 months after treatment compared with water-inoculated and noninoculated controls. Sap flow velocity (midday) was significantly lower in the infected trees compared with that in the controls. Sap flow velocity also was inversely correlated with the proportion of bark area with cankered tissues and with tylose abundance in the youngest two growth rings. Tylose formation in current-year vessels associated with C. smalleyi infections is likely responsible for much of the water transport disruption. It is hypothesized that multiple stem infections of C. smalleyi and the resulting xylem dysfunction contribute to crown wilt development in bitternut hickory exhibiting rapid crown decline.
由 Ceratocystis smalleyi 引起的数百个溃疡与北美中北部和东北部遭受 Hickory bark beetle 攻击的 bitternut hickory 的快速树冠衰退有关。受真菌侵染的变色边材通常位于溃疡下方。进行了田间研究以检验以下假设：C. smalleyi 感染会导致感染树木的血管系统功能障碍。在健康的 bitternut hickory 树干（高度为 1.4 米时直径为 13 至 28 厘米）的 1.8 至 3.8 米处对 50 个 C. smalleyi 接种物进行接种，与水接种和未接种对照相比，在治疗后 12 至 14 个月会导致广泛的溃疡形成和边材变色。与对照相比，受感染树木的 sap 流速（中午）明显降低。 sap 流速还与树皮面积中带有溃疡组织的比例以及最年轻的两个生长轮中的树胶含量呈负相关。与 C. smalleyi 感染相关的当年导管中的树胶形成可能是造成大部分水运输中断的原因。据推测，C. smalleyi 的多次茎感染和由此导致的木质部功能障碍导致了快速树冠衰退的 bitternut hickory 树冠萎蔫的发展。
