|Prior, Stephen - Steve|
|MCELROY, S - Auburn University|
|Torbert, Henry - Allen|
Submitted to: American Society of Agronomy Branch Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/26/2014
Publication Date: 2/2/2015
Citation: Runion, G.B., Prior, S.A., Price, A.J., Mcelroy, S., Torbert III, H.A. 2015. Elevated CO2 effects on ragweed ecotypes: growth and fungal associations. American Society of Agronomy Branch Meeting. [https://www.agronomy.org/membership/branches/southern].
Technical Abstract: Herbicide resistant weeds exit due to repeated herbicide application. Elevated CO2 has positive effects on plant growth including weeds; however, effects on herbicide resistant weeds is unknown. Glyphosate resistant and susceptible ragweed (Ambrosia artemisiifolia L.) ecotypes were exposed to ambient or elevated (ambient + 200 ppm) CO2 for 8 weeks at which time they exhibited disease symptoms. Elevated CO2 resulted in greater top, root, and total plant biomass. Herbicide resistant plants also had greater top, root, and total biomass than susceptible plants. There were no significant CO2 by ecotype interactions. Fungi from 13 genera were associated with ragweed; several of which can be either pathogens (i.e., Alternaria, Fusarium, Rhizoctonia) or saprophytes existing on dead plant tissues. Powdery mildew was higher on susceptible compared with resistant ragweed. Susceptible plants also had an increased frequency of Rhizoctonia on leaves and Alternaria on stems; however, Fuarium was more frequent on resistant ragweed leaves. Fungi were not affected by CO2 level or its interaction with ecotype. This is the first study to report effects of herbicide resistance and elevated CO2 on fungi associated with weeds.