For quite a few years now, I've been using White Poplar sticks exclusively for smoking/cooking. I cut a green tree that is a bit bigger than my thumb, cut it into pieces about 4" long and put a couple or three in the smoke box. I am using a Grill Pro Heavy Duty, but used a Brinkman Smoke-n-Grill for years. DO NOT use Black Poplar, as it will smell like very dirty feet! The extra sticks go in a coffee can and into the freezer, thus ensuring a steady supply of green sticks!! I sometimes split the bigger sticks. Mmmmm. Nothing like a batch of baby pork ribs smoked/cooked with good old White Poplar! Shake a bit of Greek seasoning on, smear on some BBQ sauce of some sort. I also cut up an onion and dump any aging or leftover BBQ sauce in the water tub. I am going to smoke/cook a beef roast tomorrow and make soup with the drippings in the water tub.