okay, Anything that will take out the mould risks taking out the clour of the cloth so use cautiously, the aim is to get the mould out before the cloth starts to fade.
first try should be lemon juice or white vinegar, mixed with salt. Apply, rub gently and wash as usual DO NOT TUMBLE dry until you are sure that the mould is out or you have given up. Dry in sunshine if you can. If this works and the colour isn't coming out of the cloth then keep doing it gently. It might take many more than one try, but if its working don't be tempted to rub harder or leave the fabric soakingIf it doesn't then you may want to try a proprietary stain remover (trust pink for instance, again use with caution if you don't want to bleach the cloth.
hope this helps