YOu would think the corn stalks would be the worst place but I dont know. I calve on pasture and will have  a calf a year maybe with it. It always seems to be the calves that will hide out and stay laying down alot the first few days. I want to think dew has alot to do with it too and keeps the navel from drying up fast. I used to use iodine and my vet thought it would keep a navel from drying up like it should at times and started using a Vetricyn product for navels. It says it helps the navel dry up faster and seems like it does. I have found that late calves born when the weather gets hotter tend to have more trouble too and they seem to want to hide out. Do you remember having any trouble way back with this calf? Since he is home raised It makes me think less it is mycoplasma but still could be. Have you ever had any mycoplasma before? Do you buy calves and bring in to mix with home raised?