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Title: Interaction of a preventative fungicide treatment and root rot pathogen on ambrosia beetle attacks during a simulated flood event

Author
item ADDESSO, KARLA - Tennessee State University
item BAYSAL-GUREL, FULYA - Tennessee State University
item OLIVER, JASON - Tennessee State University
item Ranger, Christopher
item ONEAL, PAUL - Tennessee State University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2018
Publication Date: 7/14/2018
Publication URL: https://handle.nal.usda.gov/10113/6472479
Citation: Addesso, K., Baysal-Gurel, F., Oliver, J., Ranger, C.M., O'Neal, P. 2018. Interaction of a preventative fungicide treatment and root rot pathogen on ambrosia beetle attacks during a simulated flood event. Insects. 9:1-11. doi:10.3390/insects9030083.
DOI: https://doi.org/10.3390/insects9030083

Interpretive Summary: Flooding can increase tree susceptibility to root rot pathogens as well as attacks by ambrosia beetles attracted to stress-induced ethanol emissions. These experiments investigated the interaction of a preventative fungicide treatment and infection with Phytophthora cinnamomi root rot on ambrosia beetle attacks in flood stressed trees. Redbud and tulip poplar trees were evaluated in two flood trials with their respective non-fungicide and non-inoculated controls for a total of four treatments – control, fungicide, inoculated control, and inoculated + fungicide. Fungicide treated trees had fewer ambrosia beetle attacks, particularly in trees without P. cinnamomi co-infection. In a follow-up experiment, redbuds trees were evaluated for ethanol production to determine if differences in ethanol could explain why fewer ambrosia beetle attacks were observed in fungicide treated trees. All flood stressed trees began producing ethanol within 24 h post flooding, regardless of fungicide or P. cinnamomi treatment. We conclude that pre-treatments of a fungicide can provide some protection from ambrosia beetle attacks during an extreme flood event, but that protection is reduced if a root rot pathogen is also present. Additionally, the rejection of fungicide treated trees does not appear to be related to the absence of ethanol, the key host attractant of ambrosia beetles.

Technical Abstract: looding can increase tree susceptibility to root rot pathogens as well as attacks by ambrosia beetles attracted to stress-induced ethanol emissions. These experiments investigated the interaction of a preventative fungicide treatment and infection with Phytophthora cinnamomi root rot on ambrosia beetle attacks in flood stressed trees. Redbud and tulip poplar trees were evaluated in two flood trials with their respective non-fungicide and non-inoculated controls for a total of four treatments – control, fungicide, inoculated control, and inoculated + fungicide. Fungicide treated trees had fewer ambrosia beetle attacks, particularly in trees without P. cinnamomi co-infection. In a follow-up experiment, redbuds trees were evaluated for ethanol production to determine if differences in ethanol could explain why fewer ambrosia beetle attacks were observed in fungicide treated trees. All flood stressed trees began producing ethanol within 24 h post flooding, regardless of fungicide or P. cinnamomi treatment. We conclude that pre-treatments of a fungicide can provide some protection from ambrosia beetle attacks during an extreme flood event, but that protection is reduced if a root rot pathogen is also present. Additionally, the rejection of fungicide treated trees does not appear to be related to the absence of ethanol, the key host attractant of ambrosia beetles.