According to some archeologists, the 10th biblical plague of Egypt may have been caused when the Egyptian people gave their firstborn sons the largest share of their grain. The grain may have been laden with aspergillus niger, a fungus that can be toxic in large quantities. Today, aspergillus niger can contaminate plants that grow in the ground, such as onions or peanuts. Plants contaminated with aspergillus niger have recognizable symptoms.
On plants such as onions or peanuts, aspergillus niger can cause black mold to develop on bruised tissue, such as the roots or the neck where the vegetable meets the stalk. Often black mold will appear as a black discoloration after the vegetables have been pulled from the ground and stored for some time in a dark location with little ventilation. Other symptoms include clusters of dark spores along the veins of tissue. The infected tissue may have a soaked or waterlogged appearance at first, but may eventually develop a shriveled, sunken look.
Fruit or nut trees such as pistachio often develop a fungus known as aspergillus blight due to irrigation practices in which a drip irrigation line is buried in the soil. Nut growers often use buried drip irrigation lines to irrigate these trees because it reduces the chances that the tree develops alternaria late blight, a fungal infection caused by flood irrigation. The trees develop aspergillus blight due to the presence of aspergillus niger in the soil. Nuts that develop apergillus blight have shells that are stained bright yellow.
Aspergillus Crown Rot
Crown rot is similar to black mold in that it may appear in the neck of peanuts or other plants grown in the soil. But unlike black mold, crown rot will cause plants to die while they are still in the ground. When plants first develop crown rot, they may appear to be infected by leaf spot or leaf scorch. But if you dig down so that the lower crown of the plant is exposed, you will see that the tissue around the lower crowns will appear brown and rotted. There may also be black spores present. The disease primarily strikes young plants such as seedlings or plants that are already weakened by stress. The plants will wilt and die.