I think it is Cornelia because plants and trees use water to grow so they woul'nt be affected as much سے طرف کی water (Irma is my least favourite character and Cornelia is my favourite)
i think they both strong because i remember in comic, there are a scene when cornelia and irma angry and blown out their power, and their power become a mud (earth + water=mud) , one who stopped this is Will.
but, if i would pick, i choose irma, water can broke the plants
OK I LIKE IRMA مزید THAN CORNELIA IRMA IS MY پسندیدہ CORNELIA IS MY LEAST پسندیدہ AND WATER IS MY پسندیدہ ELEMENT BUT I THINK THAT IS EARTH IS THE MOST POWERFULL ELEMENT OF ALL یا AT LEATST IT WAS کہا سے طرف کی THE W.I.T.C.H COMICS FROM THE NEW POWER SAGA
Well... I hate to say this, but I think earth is stronger, after all, it's not just plants and trees that Cornelia can grow, she can make earth quakes and اقدام rocks. Irma can make those tsunami, but Cornelia can regrow the plants.