Surreal illustration of an onion battling fungal diseases in a refrigerator.

Onion Storage SOS: How to Keep Your Onions Fresh and Rot-Free!

Nico Varela in Health & Wellness December 2025 • 4 min read.

"Don't let onion rot ruin your recipes! Learn the secrets to storing onions for long-lasting freshness and flavor."

Onions are a kitchen staple, adding flavor to countless dishes worldwide. Yet, these pungent bulbs are surprisingly delicate when it comes to storage. One of the biggest challenges? Storage rot, a common issue caused by bulb-rotting fungi that can lead to significant losses. Imagine reaching for an onion only to find it soft, moldy, and unusable – a frustrating experience for any cook.

In Bangladesh, where onions are a crucial part of the cuisine, researchers have been studying the best ways to combat storage rot. A recent study focused on understanding how different storage conditions and onion varieties affect the incidence of disease. This research, conducted across various markets and storage facilities, provides valuable insights into keeping your onions fresher for longer.

Whether you're a seasoned gardener, a passionate home chef, or simply someone looking to reduce food waste, understanding the factors that contribute to onion storage diseases is essential. Let's explore the key findings from this study and uncover practical tips to help you prevent onion rot and enjoy the full flavor of your onions every time.

Unveiling the Culprits: Common Fungal Diseases in Stored Onions

Surreal illustration of an onion battling fungal diseases in a refrigerator.

The primary cause of onion storage issues is fungal diseases. Several types of fungi thrive in storage environments, leading to bulb rot and spoilage. Identifying these culprits is the first step in preventing them from wreaking havoc on your onion supply. Some of the most common fungal diseases include:

These fungi can attack onions in various ways, leading to different types of rot. Factors like temperature, humidity, and physical damage can all influence the development and spread of these diseases. Understanding the conditions that favor fungal growth is crucial for implementing effective storage strategies.

Black Mold Rot (Aspergillus niger): Thrives in high temperatures and humidity.
Blue Mold Rot (Penicillium spp.): More common in cooler conditions.
Fusarium Bulb Rot (Fusarium spp.): Can cause significant damage, leading to soft and mushy bulbs.
Basal Rot (Fusarium moniliforme): Affects the base of the bulb, causing decay.
Dry Rot (Macrophomina phaseolina): Results in dry, shrunken bulbs.

Beyond these common fungal diseases, other less frequent but still problematic issues include Smudge, Grey neck rot, White rot and Anthracnose. Proper identification of the specific disease affecting your onions can help you tailor your storage methods and take preventative measures.

Small Changes, Big Impact: Simple Steps to Maximize Onion Freshness

By understanding the science behind onion storage and implementing practical strategies, you can significantly extend the shelf life of your onions and reduce food waste. Remember, every small step you take – from choosing the right variety to optimizing storage conditions – contributes to keeping your onions fresher, flavorful, and ready to use in your favorite recipes. So, take control of your onion storage, and enjoy the delicious rewards!

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.3329/pa.v26i1.24515, Alternate LINK

Title: Storage Diseases Of Onion Under Variable Conditions

Subject: Pharmaceutical Science

Journal: Progressive Agriculture

Publisher: Bangladesh Journals Online (JOL)

Authors: Ms Mahmud, Ms Monjil

Published: 2015-08-12

Everything You Need To Know

What are the most common fungal diseases that cause onion storage rot, and what conditions do they thrive in?

The most common fungal diseases include Black Mold Rot (Aspergillus niger), which thrives in high temperatures and humidity; Blue Mold Rot (Penicillium spp.), more common in cooler conditions; Fusarium Bulb Rot (Fusarium spp.), which causes soft and mushy bulbs; Basal Rot (Fusarium moniliforme), affecting the base of the bulb; and Dry Rot (Macrophomina phaseolina), resulting in dry, shrunken bulbs. Understanding these conditions is crucial for effective storage strategies to minimize spoilage. Less frequent diseases such as Smudge, Grey neck rot, White rot and Anthracnose can also impact storage.

How does temperature and humidity affect the development of fungal diseases in stored onions?

Temperature and humidity play a significant role in the development and spread of fungal diseases. For example, Black Mold Rot (Aspergillus niger) thrives in high temperatures and humidity, while Blue Mold Rot (Penicillium spp.) is more common in cooler conditions. Maintaining proper environmental control, such as adequate ventilation and appropriate temperature, is essential to inhibit fungal growth and prevent bulb rot. Without control of these factors fungal growth is hard to prevent. Physical damage can also influence the development and spread of these diseases.

What practical steps can home cooks and gardeners take to maximize onion freshness and extend their shelf life, and why is variety selection important?

To maximize onion freshness, implement strategies such as choosing the right variety, optimizing storage conditions (temperature and humidity), and ensuring proper ventilation. Variety selection is important because some onion varieties are more resistant to storage diseases than others. By understanding the science behind onion storage and implementing practical strategies, you can significantly extend the shelf life of your onions and reduce food waste. Proper identification of the specific disease affecting the onions can help tailor storage methods and preventative measures.

What are the implications of storage rot for cooks, and how does understanding fungal diseases help in preventing food waste?

Storage rot can lead to significant losses, causing frustration when cooks reach for an onion only to find it soft, moldy, and unusable. Understanding fungal diseases like Black Mold Rot (Aspergillus niger), Blue Mold Rot (Penicillium spp.), Fusarium Bulb Rot (Fusarium spp.), Basal Rot (Fusarium moniliforme), and Dry Rot (Macrophomina phaseolina) allows for targeted storage methods, preventing spoilage and reducing food waste. Implementing strategies based on this knowledge ensures onions remain fresher, flavorful, and ready for use.

In what ways can understanding the causes of onion storage diseases, such as Fusarium Bulb Rot, Basal Rot and Dry Rot, help both home cooks and gardeners make more informed decisions about storage?

Understanding the causes of onion storage diseases allows for more informed decisions about storage environments and practices. For example, knowing that Fusarium Bulb Rot (Fusarium spp.) causes soft, mushy bulbs, Basal Rot (Fusarium moniliforme) affects the base, and Dry Rot (Macrophomina phaseolina) results in dry, shrunken bulbs helps in identifying early signs of spoilage. This knowledge enables home cooks and gardeners to adjust storage conditions, such as temperature and humidity, and implement preventative measures to minimize losses and maintain onion quality. Additionally, identifying the specific diseases early helps to tailor the approach to the storage.