Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA.
Pest Manag Sci. 2012 Apr;68(4):529-36. doi: 10.1002/ps.2281. Epub 2012 Jan 30.
Since the discovery of Agrilus planipennis Fairmaire (emerald ash borer) in 2002, researchers have tested several methods of chemical control. Soil drench or trunk injection products containing imidacloprid are commonly used to control adults. However, efficacy can be highly variable and may be due to uneven translocation of systemic insecticides. The purpose of this study was to determine whether sectored xylem anatomy might influence imidacloprid distribution in tree crowns.
Imidacloprid equivalent concentrations were higher in leaves from branches in the plane of the injection point (0°) than in leaves from branches on the opposite side of the injection point (180°). Leaves from branches 90° to the right of injection points had higher imidacloprid equivalent concentrations than leaves from branches 90° to the left of injection points. Leaves and shoots had higher imidacloprid equivalent concentrations than roots and trunk cores, indicating that imidacloprid moves primarily through the xylem.
Imidacloprid equivalent concentration in leaves varied over time and in relation to injection points. It is concluded that ash trees have sectored 'zigzag' xylem architecture patterns consistent with sectored flow distribution. This could lead to variable distribution of imidacloprid in tree crowns and therefore to variable control of A. planipennis.
自 2002 年发现天牛（翡翠灰蓝木蠹蛾）以来，研究人员已经测试了几种化学控制方法。土壤淋洗或树干注射含有噻虫啉的产品通常用于控制成虫。然而，效果可能高度可变，这可能是由于系统性杀虫剂的不均匀转移。本研究旨在确定扇形木质部解剖结构是否会影响树冠中噻虫啉的分布。
注射点（0°）平面上的树枝的叶片中噻虫啉当量浓度高于注射点对面（180°）的树枝的叶片。注射点右侧 90°的树枝上的叶片中的噻虫啉当量浓度高于注射点左侧 90°的树枝上的叶片。叶片和嫩枝的噻虫啉当量浓度高于根和树干芯，表明噻虫啉主要通过木质部移动。
叶片中的噻虫啉当量浓度随时间和注射点而变化。结论是，灰树具有扇形“之字形”木质部结构模式，与扇形流量分布一致。这可能导致树冠中噻虫啉分布不均匀，从而导致对天牛的控制效果不均匀。
