What Crops Are Affected by Mycotoxins? A Guide to Fungal Contamination

November 4, 2025 •

3 min read

Globally, an estimated 25% of the world's crops are affected by mycotoxins, resulting in significant economic losses and potential health risks. It is crucial to understand what crops are mycotoxins, or more accurately, the crops that are most susceptible to mycotoxin contamination, to safeguard public health and ensure food security.

Quick Summary

This article explores the common crops that can be affected by mycotoxin contamination, outlining the primary fungal sources and the environmental conditions that promote toxin production. It details preventive measures and distinguishing mycotoxins from simple mold growth.

Key Points

Prevalent in Cereals and Nuts: Mycotoxins, particularly aflatoxins, fumonisins, and deoxynivalenol (DON), frequently contaminate grains like corn, wheat, rice, and peanuts.
Produced by Common Fungi: Toxigenic molds such as Aspergillus, Fusarium, and Penicillium are the primary culprits behind mycotoxin production.
Caused by Poor Conditions: Warm, humid climates, as well as inadequate drying and storage, are key factors that promote fungal growth and mycotoxin contamination.
Stable and Persistent: Mycotoxins are chemically stable and can survive standard food processing techniques, making them difficult to eliminate.
Threat to Human and Animal Health: Exposure to mycotoxins can cause both acute poisoning and chronic issues like cancer and immune suppression in humans and livestock.
Prevention is Key: The most effective control strategies focus on preventing fungal growth in the field and ensuring proper drying and storage of harvested crops.

Understanding Mycotoxins and Their Fungal Origin

Mycotoxins are toxic secondary metabolites produced by certain fungi or molds that can colonize various crops. While not all mold produces mycotoxins, specific conditions like warm, humid climates and improper storage increase the risk. The fungi can contaminate crops before and after harvest, and the mycotoxins are stable, often surviving food processing. The main mycotoxin-producing fungi genera are Aspergillus, Fusarium, and Penicillium. These molds produce toxins that can harm humans and livestock, causing issues from acute poisoning to long-term health problems.

Key Mycotoxin Groups and Affected Crops

Certain mycotoxins are linked to specific fungi and crops.

Aflatoxins: Produced by Aspergillus flavus and A. parasiticus, they are a major threat, especially in warm climates. Crops often affected include cereals (corn, rice), oilseeds (peanuts), and tree nuts (pistachios, almonds).
Ochratoxin A: Produced by Aspergillus and Penicillium, found globally. Commonly contaminates cereals, coffee beans, dried fruit, and spices. Often occurs during inadequate storage.
Fusarium Mycotoxins: This group includes DON, fumonisins, and zearalenone, produced by Fusarium species. They infect crops before harvest, particularly in moderate to cool, wet conditions.
- DON and ZEA: Found in cereal grains like wheat, corn, and barley.
- Fumonisins: Primarily affect corn and maize products.

The Most Vulnerable Crops

Some crops are particularly susceptible due to their growth and storage needs:

Cereals: Corn, wheat, rice, barley, and oats are highly prone to Fusarium and Aspergillus mycotoxins.
Nuts and Oilseeds: Peanuts, pistachios, almonds, and cottonseed are frequent hosts for aflatoxin-producing molds, especially in warm, humid storage.
Dried Fruits: Figs, raisins, and prunes can be contaminated with ochratoxin A and aflatoxins.
Coffee Beans: Improper handling can lead to Ochratoxin A contamination.
Apples and Apple Products: Patulin is linked to rotting apples and found in apple juice.

Factors Causing Mycotoxin Contamination

Mycotoxin production is complex, influenced by environment and agriculture. Fungi need specific conditions to produce toxins.

1. Environmental Conditions

Temperature and Humidity: Molds thrive in warm, humid areas.
Drought Stress: Stressed crops are more vulnerable to infection.

2. Agricultural Practices

Pre-Harvest: Includes soil, pests, and tillage.
Post-Harvest: Crucially, poor drying and inadequate storage allow mycotoxins to proliferate in moist conditions.

Strategies for Prevention and Control

Controlling mycotoxins requires action across the food chain.

Field Management: Practices like crop rotation and pest control reduce initial contamination.
Proper Storage: Drying crops thoroughly and storing them in cool, dry places is vital.
Food Processing: Regulations set maximum mycotoxin limits. Processing can reduce levels, but often doesn't eliminate them.
Monitoring: Testing helps identify contaminated batches.

Mycotoxin vs. Fungal Contamination


Feature	Mycotoxins	Fungal Contamination
Nature	Toxic chemical compounds.	Presence of mold/fungi.
Appearance	Invisible; odorless/tasteless.	Often visible mold.
Persistence	Stable, resistant to processing.	Mold can be killed, toxins remain.
Toxicity	Poisonous at low concentrations.	Fungi cause issues, mycotoxins cause mycotoxicosis.
Cause	Produced by certain fungi under stress.	Caused by poor conditions favoring growth.

Conclusion

Mycotoxin contamination is a major global food safety issue. Crops like cereals, nuts, and dried fruits are highly susceptible to toxins from molds like Aspergillus, Fusarium, and Penicillium. Contamination results from pre- and post-harvest factors, including environment and practices. Preventing fungal growth through good agriculture, proper storage, and testing effectively reduces risk. Consumers can reduce exposure by checking food, storing it correctly, and eating a varied diet. Research continues on detection and detoxification methods.

Frequently Asked Questions

A mycotoxin is a toxic chemical compound produced naturally by certain types of fungi or molds. They are not the fungi themselves, but a toxic byproduct of their metabolism.

The most vulnerable crops include cereals (corn, wheat, barley), nuts (peanuts, pistachios), oilseeds (cottonseed, sunflower seeds), dried fruits (figs, raisins), and coffee beans.

Crops can be contaminated in the field before harvest by 'field fungi' like Fusarium, or after harvest during storage by 'storage fungi' like Aspergillus and Penicillium, especially under warm and humid conditions.

Most mycotoxins are resistant to standard food processing, including heat from cooking, baking, and roasting, meaning they often remain in the food even after it has been prepared.

Exposure can lead to a range of health issues, including acute poisoning with symptoms like nausea and vomiting, and chronic effects such as cancer, kidney damage, and immune system suppression.

To reduce exposure, you should inspect grains and nuts for signs of mold, discard any discolored or shriveled food, store food properly in dry conditions, and maintain a diverse diet.

Mold is the fungus itself, which can be visible. A mycotoxin is the invisible, toxic substance that some molds produce. A food can contain mycotoxins even if the mold that produced it is no longer alive.