Smoky blotch or Sooty blotch occurs as a superficial black covering on the rind of citrus fruits. The black colouring is due to the growth of fine fungal threads that live on the surface tissue of the fruit. Sooty blotch is common on the coast after a wet autumn or winter. Both shade and high humidity are conducive to its development, with fruit on the southern sides and inside of trees most affected. Although causing only superficial damage it makes the fruit unsightly. Good packing line procedures will normally remove the blemish.