I have a large oriental poppy plant in my garden. I did have 25 poppy heads on it but the other day I noticed one had broken off. On closer inspection I noticed where the head had broken off there was a black sticky tar like substance. I have since lost another 4 poppy heads to the same thing. I have removed the stems and cut them length ways to find out if this sticky black substance goes down the whole stem. If doesn't and just seems to be at the top where the head has broken. Can any one tell me what this is and if there is anything I can do to prevent loosing any more poppies?
If they've already blossomed this is normal condition of plants. They'll continue to die back until fall, when they will regenerate in preparation for winter.
If your poppies are the opium poppy (illegal to grow here in the U.S) then the substance is probably opium tar, which is usually harvested in the Middle East...
If all this isn't a description of your problem, and the flowers haven't yet blossomed then I'd check the undersides of the leaves for mites...
Inclined to agree with Clanad .... Papaver somniferum ( if that is what your plant is) will ooze a liquid which is opium , lovely flowers with a deadly secret!