Effects of biochar on ambrosia beetle attacks on redbud and pecan container trees

Authors: MONTERROSA, ALEJANDRA - University Of Georgia; Acebes-Doria, Angelita; BLAAUW, BRETT - University Of Georgia; JOSEPH, SHIMAT V - University Of Georgia

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2023
Publication Date: 6/28/2024
Citation: Monterrosa, A., Acebes-Doria, A.L., Blaauw, B., Joseph, S. 2024. Effects of biochar on ambrosia beetle attacks on redbud and pecan container trees. Florida Entomologist. 107(1). https://doi.org/10.1515/flaent-2024-0036.
DOI: https://doi.org/10.1515/flaent-2024-0036

Interpretive Summary: Ambrosia beetles are a serious pest of ornamental nurseries and tree and nut orchards. The trees can be under various types of stress, such as flood, frost, or drought. The stress trees release stress signals, mostly ethanol, from the tree trunk. When ambrosia beetle adults are in flight, they attack the stressed trees in production. Reducing tree stress is one of the strategies to mitigate ambrosia beetle attacks. Biochar is organic matter produced by controlled burning at high temperatures. It is applied as a soil amendment and has improved the soil properties by reducing tree stress and altered levels of naturally occurring defensive chemicals providing pest management opportunities. In the current study, biochar-treated containers had no or low levels of ambrosia beetle attacks on redbud trees compared to non-treated trees.

Technical Abstract: Mitigating tree stress can be a valuable strategy to combat ambrosia beetles, such as granulate ambrosia beetle, Xylosandrus crassiusculus (Motschulsky). Ambrosia beetles attack stressed trees that release ethanol. Biochar and kaolin clay are known for their stress-relieving properties but not determined against ambrosia beetle in ornamental or pecan (Carya spp.) trees. Although ento-mopathogenic fungi, Beauveria bassiana, and Trichoderma spp. have shown evidence of effectiveness against adults of ambrosia beetles, their role in reducing tree attacks is unclear. Thus, the objective was to determine the effects of biochar, kaolin clay, permethrin (industry standard), and entomopathogenic fungi on reducing the ambrosia beetle attack on young redbud (Cercis spp.) and pecan trees. The treatments were biochar, kaolin clay, permethrin, biochar + permethrin, kaolin clay + permethrin, B. bassiana, Trichoderma spp., and nontreated control. Compared to the non-treated treatment, biochar, and biochar + permethrin treatments significantly reduced ambrosia beetle attacks on redbud trees. Kaolin clay, permethrin, B. bassiana, and Trichoderma spp. did not significantly reduce the number of ambrosia beetle attack holes when compared with the non-treated control. This suggests that biochar has a potential to reduce ambrosia beetle attacks on ornamental trees and should be further evaluated for longer-term effects for multiple seasons.