P. citreonigrum is not a commonly isolated species, but it is widely distributed.P. citreonigrum grows in rice after harvest, when the moisture content reaches 14.6%. At 1% higher moisture, other fungi will overgrow it, so the moisture band for invasion is narrow. The fungus is reported to be favoured by the lower temperatures and shorter hours of daylight occurring in the more temperate rice growing areas. The Oriental disease known as "beriberi" has traditionally been regarded as a nutritional disease, an avitaminosis. However, beriberi is more than a single disease, and one form of it, known in Japan as acute cardiac beriberi, has been established to be a mycotoxicosis. Acute cardiac beriberi in Japan is now only of historical interest. However, P. citreonigrum and Citreoviridin may still occur in other parts of Asia. Citreoviridin is also produced by P. ochrosalmoneum