Identification and Control of Botrytis on Garlic, Onion and Shallot Bulbils

Botrytis, also known as gray mold, is a pathogenic fungus that can infect garlic, onions, and shallots. The most common species are Botrytis cinerea , Botrytis allii , and Botrytis squamosa . This article will help you identify signs of contamination and implement effective methods to control this fungus.

Summary

• Identification of Botrytis Contamination
• Methods of Controlling Botrytis
• Prevention of Contamination
• Detailed Processing Steps
• FAQ
• Economic Impact
• The most resistant garlic varieties
• The most resistant onion varieties
• The most resistant shallot varieties

Identification of Botrytis Contamination

Botrytis contamination can manifest itself in different ways on garlic, onion and shallot:

• Garlic: Symptoms include watery spots on leaves and bulbs, which develop into soft rot, often accompanied by a gray, velvety fungal growth.
• Onion: Symptoms include water spots on leaves and bulbs, soft rot, and gray mold growth. Leaves may also have white lesions caused by Botrytis squamosa .
• Shallot: Symptoms are similar to those seen on onion, with spots on leaves and bulbs and the development of gray mold.

Methods of Controlling Botrytis

To combat Botrytis, several methods can be implemented:

• Cultural hygiene: Remove and destroy infected plant debris to reduce sources of inoculum.
• Chemical treatment: Use appropriate fungicides according to local recommendations. Be sure to follow the manufacturer's instructions for maximum effectiveness.
• Crop rotation: Avoid growing alliums (garlic, onion, shallot) in the same soil for several consecutive years to reduce pathogen buildup.

Prevention of Contamination

Prevention is essential to minimize the risks of contamination by Botrytis:

• Aeration and drainage: Ensure good air circulation and adequate drainage to reduce excessive moisture, which promotes the growth of Botrytis.
• Plant Spacing: Plant bulbils with sufficient spacing to avoid crowding and improve air circulation.
• Humidity Control: Avoid overwatering and evening watering to limit prolonged moisture on leaves and bulbs.
• Use resistant varieties: When possible, choose disease-resistant varieties of garlic, onion, and shallot.

Detailed Processing Steps

Here is a step-by-step guide to treating Botrytis with fungicides:

1. Identify infected areas and remove affected plant debris.
2. Choose a fungicide recommended for Botrytis, such as fungicides based on boscalid, pyraclostrobin, or cyprodinil.
3. Mix the fungicide according to the manufacturer's instructions.
4. Apply the fungicide evenly to the plants, concentrating on infected areas.
5. Repeat treatment according to the recommended schedule, generally every 7 to 14 days during periods of high humidity.

Economic Impact

Botrytis can have a significant economic impact on garlic, onion, and shallot crops, resulting in yield losses and reduced product quality. Proactive management of this disease is essential to minimize these losses and ensure profitable production.

FAQ about Botrytis

Here are some frequently asked questions about Botrytis:

• When is the best time to apply fungicides? It is generally recommended to apply fungicides during periods of high humidity or rain, when the risk of contamination is highest.
• Are biological treatments effective against Botrytis? Some biological treatments, such as plant extracts or beneficial microorganisms, can help reduce Botrytis infections, but they are often less effective than chemical fungicides.

The most Botrytis-resistant garlic varieties

• Garlic Autumn Thermidrome
• Garlic Autumn Messidrome
• Clédor Spring Garlic

The most Botrytis-resistant onion varieties

• Setton Onion
• Red Baron Onion
• Shakespeare Onion

The most Botrytis-resistant shallot varieties

• Melkior Shallot
• Yellow Moon Shallot
• Biztro Shallot