Innovative Practices to Control Ambrosia Beetles
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are important pests of nursery crops. This study evaluated systemic fungicides alone or with an insecticide (permethrin) for preventing ambrosia beetle attacks on flood-stressed containerized Eastern redbud (Cercis canadensis L.) trees in the presence or absence of Phytophthora cinnamomi Rands. For Objective 1, multiple systemic fungicides were tested in repeated trials as container substrate drenches 1 or 3 wk before root flooding. For Objective 2, effective fungicides from Objective 1 (Orkestra Intrinsic [hereafter Orkestra], Segovis, or Subdue MAXX [hereafter Subdue] applied 3 wk before flooding) were tested in repeated trials with or without permethrin trunk sprays (applied 2 d before flooding). In all experiments, treatments were divided into groups with or without P. cinnamomi inoculations. Tests were conducted near forest borders at the Tennessee State University Otis L. Floyd Nursery Research Center, McMinnville, TN. For Objective 1, ambrosia beetle attacks were reduced by Orkestra, Empress and Subdue drench applied 3 wk before flooding in non-inoculated trees. Orkestra and Pageant Intrinsic [hereafter Pageant] also prevented the formation of beetle galleries when drenched 3 wk before flooding in inoculated or non-inoculated trees. Empress Intrinsic [hereafter Empress] and Subdue applied 1 wk before flooding prevented gallery formation in non-inoculated trees, but also worked in Phytophthora inoculated trees if applied 3 wk pre-flooding. No systemic fungicide reduced Phytophthora root rot after 3 wk of flooding. For Objective 2, Orkestra with permethrin consistently reduced ambrosia beetle attacks and inhibited gallery formation in inoculated or non-inoculated trees. In addition, permethrin with Segovis or Subdue reduced ambrosia beetle attacks and gallery formation, but inconsistently in different trials. Overall, fungicides applied 3 wk before flooding was more effective in preventing beetle attacks than 1 wk before flooding, indicating more time before flooding events may improve fungicide translocation and protection. Moreover, trees inoculated with Phytophthora received more ambrosia beetle attacks than non-inoculated trees, indicating disease stress was detrimental to trees and fungicide protection from beetles. In conclusion, some fungicides can prevent ambrosia beetle damage in tree crops and combining fungicides with an insecticide like permethrin provided a greater enhancement of tree protection from ambrosia beetles.
Agriculture|Plant sciences|Plant Pathology|Organic chemistry|Entomology
Vivek Kumar Ojha,
"Innovative Practices to Control Ambrosia Beetles"
ETD Collection for Tennessee State University.