Augusta narrowed her eyes ever so slightly.  So the plants were resisting her?  "If you're not with me..."   She muttered to herself.  Now was the time to regroup herself.  There was a ball of magical energy, or so she assumed.  It seemed like the core of this plant, or another assumption on her part.  Fine.  If it was going to be stubborn, then she would pushback harder.  

First, she'd send out more of the power to engulf the ball of magical energy.  From there, she'd attempt invading the energy with her own.  She would try to pierce the outer layer so she could allow her own magical energy to act like a syringe and inject her will into the plant's core and perform a hostile takeover of sorts.  All to make the plants listen to her.  

Should that fail, the woman would instead focus her Mana through the plant again and start an internal combustion through out the plant before using her magic to snuff out the fires.  If she could perform her blade spell and her flame lances as such, it should be a piece of cake to set the plant afire and the put it out after she was done.