Black mold
Aspergillus niger
What is Black mold (Aspergillus niger)?
Aspergillus niger is a fungus found worldwide in soil, decaying vegetation, and as a post-harvest pathogen. It can cause various diseases in plants, including black mold (or black rot) of onions and garlic, and various other plants such as peanuts, table grapes, yams, Dracaena, cherry, maize, grapes, bananas, tomatoes, cotton, Sansevieria, and mango. It thrives in hot and humid conditions, often associated with irrigation practices. Symptoms vary depending on the host but can include water-soaked areas, black spore masses, soft and watery decay, root curling, vine cankers, premature fall colors, and discoloration of crops.
How does Black mold (Aspergillus niger) occur?
Aspergillus niger reproduces primarily in its asexual state, releasing conidia (spores) that are dispersed through the air, soil, and water. Conidia germinate and form hyphae, which colonize the substrate. Aerial hyphae emerge, producing conidiophores (stalks) and conidial heads that generate new conidia. Sexual reproduction can also occur but is less common. The fungus typically lives as a saprophyte on decaying matter and can become a post-harvest pathogen. Infection in plants is favored by hot, humid conditions and irrigation practices such as buried drip lines.
Symptoms
1 - Impacts on Plants
Aspergillus niger can have negative effects on plants. It can cause post-harvest decay in various crops, resulting in quality deterioration and discoloration. This can lead to significant losses in crop value and marketability.
2 - Soil and Environment
• Aspergillus niger is ubiquitous in soils, plant litter, seeds, dried fruit, and nuts. It exhibits saprophytic growth on decaying matter in soil and compost. • Moreover, it poses a potential risk of contamination in indoor environments. Its presence can cause discoloration, quality deterioration, and decreased commercial value of crops.
3 - Human Health
• In rare cases, Aspergillus niger can cause aspergillosis, primarily in immunocompromised individuals. It predominantly affects people with compromised immune systems. • Susceptible individuals may experience allergic reactions and respiratory problems when exposed to this fungus.
Solutions
1 - Prevention Measures
• Proper sanitation practices, including regular cleaning and removal of decaying organic matter. • Implementing good agricultural practices like crop rotation and proper irrigation techniques. • Ensuring proper storage and handling of harvested crops. • Maintaining adequate ventilation and humidity control in indoor environments.
2 - Fungicides for Treatment
• While chemical controls are generally not recommended for Aspergillus niger, some fungicides have shown efficacy in reducing mycelial growth and controlling certain diseases caused by the fungus. • Examples of fungicides that may be used include Thiabendazole, Fludioxonil, Azoxystrobin, Carbendazim and Imazalil. Note: It is crucial to consult with local extension specialists or agricultural experts for guidance on legal and effective fungicide products available in your region
