348 Olson et al: Neonicotinoid Applications for Emerald Ash Borer Suppression protect trees and cause up to 100% EAB mortality. However, some formulations of emamectin benzoate are restricted use insecticides, require specialized equipment to apply, and are expensive. As alternatives, imidacloprid or dinotefuran applied Figure 1. Emerald ash borer larvae feed on phloem beneath bark, creating (a) serpentine galleries that expand as the larvae grow that (b) eventually coalesce and completely girdle infested trees. suppression, again with some success. In theory, interspersing insecticide-protected trees throughout an EAB-infested area could facilitate establishment of introduced biological control agents and lead to slower ash mortality (McCullough and Mercader 2012; Davidson and Rieske 2016; Graziosi and Rieske 2017). However, the only way to assure com- plete protection of individual trees of North Ameri- can ash from EAB is through chemical means (McCullough et al. 2011). Following the initial discovery of EAB in the USA, numerous insecticides were screened for effi- cacy against both larval and adult EAB (McCullough et al. 2005; Herms et al. 2009). Emamectin benzoate, an avermectin derivative applied through trunk injec- tions at approximately 2- to 3-year intervals, is consid- ered the gold standard (Smitley et al. 2010); injections ©2020 International Society of Arboriculture as a soil drench, trunk spray, or foliar spray have been employed. Imidacloprid is metabolized by plants into byproducts with varying toxicities (Nauen et al. 1998), including imidacloprid olefin and dihydroxy imida- cloprid. Imidacloprid metabolites have demonstrated efficacy against some pests with piercing sucking mouthparts, including aphids (Nauen et al. 1998) and adelgids, and is found in eastern hemlock trees (Tsuga canadensis) treated for hemlock woolly adelgid (Adelges tsuga)(Coots et al. 2013; Eisenback et al. 2014; Benton et al. 2016). Imidacloprid olefin in par- ticular persists in treated hemlock and is highly toxic against hemlock woolly adelgid, whereas dihydroxy imidacloprid is transitory and appears unimportant for insect control in the hemlock system (Benton et al. 2016). While imidacloprid translocation has been well studied in the hemlock woolly adelgid–hemlock system (Cowles 2009; Coots et al. 2013; Eisenback et al. 2014; Benton et al. 2016), gymnosperms as a group use tracheids exclusively, rather than tracheids and vessels, for transport (Sperry et al. 2006). Thus, movement of imidacloprid and its metabolic byprod- ucts through ash, an angiosperm, is expected to differ from its movement through hemlock, a gymnosperm. Imidacloprid and dinotefuran do not provide the same level of tree protection against EAB as ema- mectin benzoate trunk injections, but both can pro- vide adequate protection when applied annually (Herms et al. 2009; Smitley et al. 2015). They require no spe- cialized equipment, are more accessible, and there- fore are widely used. These chemicals are translocated to the foliage, where adult EAB encounter them as they feed prior to mating and oviposition (Mota-Sanchez et al. 2009), but surprisingly little is known about which ash plant tissues concentrate or retain these chemicals following treatments (but see Harrell 2006; Mota-Sanchez et al. 2009; Tanis et al. 2012). Application rates and treatment frequency neces- sary for tree protection against EAB vary and are influenced by season, tree size, canopy condition, site and soil conditions, and overall tree health (Smitley et al. 2015). Consequently, there is some confusion among homeowners and tree care specialists as to optimal application rates and frequency.
September 2020
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
