Botulism ...no. Powdery mildew, Botrytis, Downey Mildew...if the buds are too wet and left in the jar enclosed for too long...yes. I would worry more about mold.
Besides, if I remember right...you get botulism when you leave open tuna (or similar foods) in the fridge in their metal container. That's one way to grow a botulism culture anyway...