what is it?

[jeannieo]

white leghorns, I got 8 of them as rescues. they are developing scab type things on their combs. this is the worst one. any ideas?

 

[Eggcessive]

It might be fowl pox, but it doesn't look typical. Check for mite infestation which also could be a cause. Peck wounds are usually black specks, and favus, a fungal infection of combs, waddles, and earlobes is usually whitish or grayish. If you have mosquitoes it may be pox though. Pox is caused by a virus spread by mosquitoes that can last about a month, and there is no treatment. Some will put iodine on the scabs to dry it up. It's not serious unless wet pox develops in some of the chickens, and that can be very deadly. Look inside the throat for any yellowish patches that might indicate wet pox. Here are some links: http://partnersah.vet.cornell.edu/avian-atlas/search/disease/510
https://www.backyardchickens.com/a/avian-pox-how-to-treat-your-chickens-for-avian-pox