Banana leaves black patches

Hi All
I had palanted few banana saplings they are growing fine but leaves have black patches what might be the reason?
experts please give advice


it could be black sigatoka

http://www.apsnet.org/publications/apsnetfeatures/Pages/blacksigatoka.aspx

Some times TC plants will have such patches for a temporary period. If you contact TC lab they can assist you.
If it is normal they will confirm, because every buyer complains them back so they will have the first hand information on this.