Poison Elven Food or Tell Alberic

Journal

I brought back the queen wolf spider venom sacks as requested by Phineas Drumplemouth. He mixed the venom with some kind of concoction his cook whipped up, then gave me a bottle of the vile solution. Now I'm tasked with finding the Bloodriver refugees' food supply and using the venom potion on it to poison their stash. Do I poison the elves' food or tell Alberic?