My biggest advice is keep turkeys away from chickens and coops or ground that has had chickens within the last several years. Chickens are a major vector for blackhead and while they can be infected they are less likely to suffer mortality from it. Turkeys, however, are extremely susceptible and vulnerable to blackhead and have no immunity to it like chickens so once it gets in your flock it can spread through them and it kills younger birds and juveniles pretty swiftly. If you already have chickens with your flock of turkeys and have never noticed any symptoms or losses from blackhead, you may not have the organism that causes blackhead in the soil where you live. If that's the case, consider yourself blessed. Another tidbit of advice, don't introduce chickens or turkeys from an outside source without fully quarantining and deworming the bird(s). Chickens don't naturally carry blackhead, its an organism that is spread via the soil and earthworms, cecal worms, and other insects. If chickens never encounter blackhead, they don't carry or spread it. I hope that makes sense.
Poultry should ideally be kept to their own kind, and another benefit of keeping them separate is to help prevent any accidental breeding attempts of chickens by toms turkeys, which can be fatal to the chicken because of the size of the turkey. I am one of the unlucky ones that has to deal with blackhead as long as I decide to keep turkeys. I have gotten my prevention and treatment down pretty well and I haven't lost any birds since my birds were around 2 months old or so, so it can be done. You just have to be hypervigilant in watching for the subtle early symptoms of it which from my experience, before the turkey starts having the ominous sulfur-colored droppings that usually indicates blackhead, there will be earlier signs that the bird is infected.
Early symptom number 1 from my experience is the bird will go off feed. Turkeys live to eat, so when one of mine goes off feed that is a big red flag. I don't always begin treatment that day, but I keep a close eye on them if I don't and isolate the bird so I can monitor droppings. I tend to watch older birds 5+ months or older a day or so before I begin treatment as they don't typically die as fast as juveniles do. At the first suspicion of blackhead in my juveniles, I begin treatment as you don't have a moment to lose.
Early symptom #2 is loose watery diarrhea. More often than not, a day up to a few days before the bird starts having sulfur-colored droppings (which is a late symptom from my experience), they will have loose watery diarrhea, often green in color. This starts right around the same time the bird goes off feed. Other symptoms include lethargy and sleepiness, lack of normal vigor and brightness, the males will stop strutting, and lack of coordination and stumbling. Very late in the illness, the bird will become abnormally indifferent to being handled and won't put up much fuss, and they often droop up with their wings hanging down to their sides in a "droopy" appearance.
Keep Metronidazole and Baytril on hand and begin treatment ASAP. I use the metronidazole tablets for older juveniles and adults, and use the water soluble powder for younger birds. I also use water-soluble bayril in powder form.
Ebay and Jedds Pigeon Supply online is where I order the meds.
@casportpony can fill in anything I may have left out.
