Sporulation of the black mold fungus, <em>Aspergillus niger</em>, on an onion seed plated onto Kritzman and   Netzer’s agar medium (the medium results in a dark brown color to the pathogen spores, which are black on most other agar media and on onion   bulbs).

Sporulation of the black mold fungus, Aspergillus niger, on an onion seed plated onto Kritzman and Netzer’s agar medium (the medium results in a dark brown color to the pathogen spores, which are black on most other agar media and on onion bulbs).

Photo Source: Lindsey du Toit, Washington State University