The most direct approach to getting rid of fungus in an herbarium is using room-temperature nitrogen.
Fungal contamination can be a significant problem for herbarium collections, threatening the integrity and longevity of valuable plant specimens. Here’s a breakdown of how to address it:
Strategies for Eliminating Fungus in Herbaria
Here’s a detailed look at methods for removing fungus from herbarium specimens:
1. Nitrogen Treatment
- Process: Specimens are treated with room-temperature nitrogen. This effectively kills the mold.
- Post-Treatment: After the nitrogen treatment, the dead mold may still need to be physically cleaned off the specimen, depending on the extent of the contamination and the desired aesthetic.
- Advantages: This method is relatively inexpensive and effective.
2. Physical Cleaning
- Process: Carefully removing visible mold with soft brushes or specialized cleaning tools.
- Limitations: This method only addresses the visible fungus and may not eliminate spores or deeply embedded fungal growth. It's often used after a treatment like nitrogen exposure.
- Best Used For: Removing surface mold after it's been killed.
3. Chemical Treatments (Use with Caution)
- Caution: Many chemicals used historically are now considered hazardous. If considering chemical treatment, prioritize safety and consult with conservation professionals.
- Examples (Historical):
- Mercuric Chloride: Highly toxic; no longer recommended.
- Thymol: A volatile antifungal agent that can be used in closed environments.
- Considerations: Chemical treatments can potentially damage the plant specimens and pose health risks to personnel. Always prioritize less invasive methods first.
4. Freezing
- Process: Subjecting specimens to very low temperatures (e.g., -20°C or lower) for a specified period.
- Efficacy: Effective for killing many types of fungi.
- Considerations: May not be suitable for all types of specimens, especially those that are very fragile. Rapid temperature changes can also cause damage.
5. Prevention
- Maintain a Dry Environment: Fungi thrive in humid conditions. Ensure the herbarium storage area is dry and well-ventilated.
- Proper Storage: Use acid-free paper and archival-quality materials for mounting and storing specimens.
- Regular Inspection: Routinely inspect specimens for signs of fungal growth. Early detection allows for prompt intervention.
- Quarantine New Specimens: Isolate newly acquired specimens until you are certain they are free of pests and fungal contamination.
Summary Table of Methods
| Method | Description | Pros | Cons |
|---|---|---|---|
| Nitrogen Treatment | Exposure to room-temperature nitrogen. | Inexpensive, effective at killing mold. | May require post-treatment cleaning. |
| Physical Cleaning | Manual removal of mold with brushes/tools. | Simple, removes visible mold. | Does not kill spores, may not remove all fungus. |
| Chemical Treatments | Application of antifungal chemicals (use with extreme caution). | Can be effective at killing fungus. | Can be hazardous, potentially damages specimens. |
| Freezing | Exposing specimens to very low temperatures. | Effective for killing many fungi. | May damage fragile specimens. |
| Prevention | Maintaining dry conditions, proper storage, regular inspection, quarantine. | Prevents fungal growth, protects collection long-term. | Requires ongoing effort. |
Ultimately, the best approach to dealing with fungus in an herbarium is a combination of prevention, early detection, and appropriate treatment methods. Nitrogen treatment offers a cost-effective and relatively safe method for killing existing mold, but ongoing vigilance is key to preserving the collection.
