DavidOnion farming can be a rewarding and profitable venture; however, it is not without its risks. Diseases can easily spread through onion farms, causing devastating losses.
The six most common diseases affecting onion farms are damping off, bacterial soft rot, Stemphylium leaf blight, purple blotch, fusarium basal rot, and alternaria leaf blight.
Fortunately, various treatments are available to help manage and prevent these diseases. By understanding the causes and treatments of these diseases, the onion you can take proactive steps to reduce the risk of disease and ensure a successful harvest.
6 Common Diseases Of Onion Farm And How To Treat
Onion plants are susceptible to numerous diseases the number of which are great. However, we have compiled 6 of the commonest diseases that occur in onion farms around the world including additional information on how to manage and control the diseases.
#1. Damping Off
Category: Fungal Disease
Damping-off, a fungal disease, is often found in onion production fields. These fungi can survive in soil for long periods and can be spread through plant debris or roots of weeds.
The disease is most severe in environments with high soil moisture and compaction.
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Causes
Damping off in onions is caused by a number of soil-borne fungi, including Pythium, Phytophthora, Fusarium, and Rhizoctonia. These fungi attack the onion seedlings just after germination, making them prone to wilting and death.
Symptoms
Symptoms of damping off include wilting and yellowing of onion seedlings. In more severe cases, roots and stems can become soft and mushy, and may rot away.
Treatment
Treatment of damping off in onions typically involves the use of fungicides. In some cases, a soil amendment such as lime may be added to raise the pH of the soil and reduce the risk of infection.
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Herbal treatments for damping off in onions can include adding neem oil or bokashi to the soil. These treatments are effective at killing the fungi that cause damping off.
Prevention
Prevention of damping off in onions can include rotating crops to reduce the risk of infection, using certified disease-free seed, and avoiding overwatering.
Control
If damping off is detected, control measures include removing infected plants and applying fungicides as soon as possible. In addition, good sanitation practices such as removing crop debris and weeds can help reduce the risk of infection.
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#2. Bacterial Soft Rot
Category: Bacterial Disease
Bacterial soft rot of onions often goes unnoticed until after the harvest, as the pathogen spreads from the neck down into the bulb, causing the water-soaked tissue to disintegrate into pulp.
Interestingly, the decay does not spread from scale to scale; it only rots a few scales while the others remain intact.
Causes
Bacterial soft rot in onions is caused by a number of bacteria, including Erwinia carotovora and Pectobacterium carotovorum. These bacteria can enter the plant through wounds or cracks in the skin, or through the roots.
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Symptoms
Soft rot in onions is characterized by soft, water-soaked lesions on the onion bulb. These lesions may start out as small spots or can quickly enlarge to cover the entire onion. The interior of the onion will become mushy and foul smelling.
Treatment
Treatment of bacterial soft rot in onions is often difficult. The best option is to remove and destroy the infected onions. If the infection is localized, a fungicide or bactericide can be applied to the affected area.
Herbal treatments for bacterial soft rot in onions include applying a mixture of garlic, horsetail, and wormwood to the affected areas. This mixture should be applied every two weeks for several months.
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Prevention
To prevent bacterial soft rot in onions, it is important to practice good sanitation. Remove any infected plants and dispose them in a sealed container. Avoid wounding or cracking the onion skin.
Control
Control of bacterial soft rot in onions can be achieved by proper sanitation and crop rotation. Plant disease-resistant varieties of onions and practice crop rotation every two to three years. Monitor the crop for signs of bacterial soft rot and take immediate action if it is detected.
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#3. Stemphylium Leaf Blight
Category: Fungal Disease
The weak fungal pathogen Stemphylium vesicarium causes Stemphylium leaf blight (SLB) of onion plants. This disease often occurs as a secondary infection, particularly when the plant is already affected by another disease or is experiencing environmental stress.
SLB develops in the form of iris yellow spot lesions and dead onion leaf tips following extreme heat stress.
Causes
The causes of Stemphylium Leaf Blight in Onions include high relative humidity, extended periods of wet weather, and infection of onion leaves by airborne spores.
Symptoms
The symptoms of Stemphylium Leaf Blight in Onions include small, tan lesions on onion leaves, lesions may coalesce, forming larger, irregularly shaped spots, and lesions may contain sporulation of the fungus.
Treatment
Treatment of Stemphylium Leaf Blight in Onions is tasking. The best treatment method is to apply fungicides to onion leaves as soon as symptoms appear.
Also, fungicides should be applied in a preventative manner to protect from, and application should be done repeatedly to ensure complete control.
Interestingly, there are herbal or organic treatments of Stemphylium Leaf Blight in Onions. first of all, you can treat with a mixture of neem oil and garlic oil or spray the mixture on affected onion leaves. You should repeat the application every 7-10 days.
Prevention
Prevention of Stemphylium Leaf Blight in Onions include keeping the relative humidity low (below 90%), avoiding overhead irrigation, removing any weeds or debris from the onion farm, and rotating onion crops with non-susceptible crops.
Control
Stemphylium Leaf Blight in Onions in Onions can be controlled by removing infected plant material from the onion farm, disposing of material in a sealed plastic bag.
Also, applying fungicides as soon as symptoms appear, planting of resistant varieties of onions, and monitoring the onion farm regularly for signs of infection are other control measures.
#4. Purple Blotch
Category: Fungal Disease
Purple blotch is a fungal disease caused by the fungus Alternaria porri. It affects onion plants and can cause significant damage to onion crops.
Throughout the entire growing season, there is a worry that fungal spores from other plants may be carried by the wind and infect wounded onion plants in the field.
Causes
The fungus is spread through spores that can be found in soil and on other onion plants. Environmental conditions such as high humidity and wet weather can also contribute to the spread of the disease.
Symptoms
The symptoms of purple blotch include purple lesions on the leaves and stems of onion plants. These lesions can cause yellowing and browning of the leaves and can eventually lead to wilting and death of the plant.
Treatment
Treatment for purple blotch includes the use of fungicides and other preventative measures. Fungicides can be applied to the plants to reduce the spread of the fungus, but the effectiveness of the treatment will depend on the severity of the infection.
Herbal treatments for purple blotch include the use of garlic, chamomile, and neem oil. These treatments can help reduce the spread of the fungus and protect the plants from further damage.
Prevention and Control
Preventative measures for purple blotch include crop rotation, avoiding wet conditions, and removing infected plants from the field. Crop rotation can help reduce the spread of the fungus, while avoiding wet conditions can help prevent the spread of spores. Removing infected plants can also help reduce the spread of the fungus to other plants.
#5. Fusarium Basal Rot
Category: Fungal Disease
Fusarium Basal Rot in onions is a fungal disease caused by the fungus Fusarium oxysporum. It is a major cause of onion disease in many parts of the world.
Cause
The Fusarium fungus lives in the soil, and thrives in warm, moist conditions. It can enter onion bulbs through wounds or cracks in the skin.
Symptoms
Symptoms of Fusarium Basal Rot include yellowing of the base of the onion and soft rot of the base. Also, brown spots on the leaves and stems, and lesions on the roots and base of the onion.
Treatment
There is no effective treatment for Fusarium Basal Rot in onions. Infected onions should be discarded. However, there is no known herbal treatment as of the time this writing is compiled.
Prevention
The best way to prevent Fusarium Basal Rot in onions is to practice good sanitation and crop rotation, and to use disease-free seed when planting.
Control
Control measures for Fusarium Basal Rot in onions include proper crop rotation, using disease-free seed, and avoiding overhead irrigation. Also, good sanitation practices, including destroying infected plants, can help control Fusarium Basal Rot.
#6. Alternaria Leaf Blight
Category: Fungal Disease
Alternaria Leaf Blight in onions is a fungal disease caused by Alternaria porri which can cause significant damage to onion crops. It is a serious problem in many parts of the world, especially in warm and humid climates.
Cause
Alternaria Leaf Blight is caused by the fungus Alternaria porri which is spread through wind-borne spores. This disease is highly active during warm and humid conditions.
Symptoms
Symptoms of Alternaria Leaf Blight include yellowing, browning, and necrotic spots on the leaves of the onion plant which eventually lead to leaf death.
Treatment
Chemical fungicides are the most common treatment for Alternaria Leaf Blight. Copper-based fungicides and strobilurin fungicides are both effective at controlling the disease.
Herbal treatments such as neem oil and garlic oil can be used to help control Alternaria Leaf Blight.
Prevention
The best way to prevent Alternaria Leaf Blight is to practice proper crop rotation and sanitation techniques. Additionally, it is important to monitor the onion crop for signs of infection and to apply fungicides as soon as symptoms appear.
Control
To help control Alternaria Leaf Blight, it is important to practice crop rotation and avoid planting onions in the same spot year after year. Also, it is important to remove any infected plants and dispose of them properly.
Onion Diseases PDF
Onion Diseases PDF describes the various types of diseases that can affect onions, including bacterial blights, viruses, fungi, nematodes, and other pathogens.
It discusses the signs and symptoms of each disease, as well as control measures for prevention and management.
It also includes information on cultural practices that can help reduce the risk of disease.
Onion Diseases Chemical Control
Onion diseases can be managed with chemical control, such as fungicides, insecticides, and nematicides.
These chemicals can be applied as foliar sprays, soil treatments, or crop drenches.
Rotating chemical treatments and using multiple modes of action can help prevent the development of resistance in pest populations.
Onion Diseases and Their Control Pdf
Onion diseases can have devastating effects on onion production, reducing yields and quality.
To mitigate these losses, effective control measures must be implemented. Proper identification of the disease and its causal agent is the first step in effective control. This guide provides an overview of some common onion diseases and their control.
The most common diseases affecting onion production include white rot (caused by the fungus Sclerotium cepivorum), leaf blight (caused by Alternaria spp.), and downy mildew (caused by Peronospora destructor).
White rot is characterized by white lesions on the leaves which may cause the plant to wilt and die. Leaf blight is characterized by yellow spots or lesions on the leaves and can be a serious problem if not controlled.
Downy mildew is characterized by a white, fuzzy growth on the underside of the leaves and can cause the leaves to yellow and die.
The most effective control measures for onion diseases include crop rotation, the use of resistant varieties, and the use of fungicides.
Crop rotation with other non-host crops is essential to reduce the build-up of inoculum in the soil and minimize the spread of disease.
The use of resistant varieties is another strategy to reduce losses due to disease. Fungicides can also be used to control onion diseases but should be used only as a last resort.
To ensure the effectiveness of control measures, it is important to monitor the crop regularly for signs of disease and take preventive measures.
Cultural practices such as proper weed control, avoiding overcrowding, and providing adequate drainage can also help reduce the spread of disease.
Finally, good sanitation practices should be followed to avoid the spread of diseases.
Onion Fungus Treatment
Onion fungus treatment typically involves the use of fungicides or other chemical agents to eradicate the fungus.
In some cases, the application of a fungicide can be combined with other treatments, such as pruning or removing affected plant parts. Also, proper hygiene and sanitation practices can help to reduce the risk of fungal infections.
Onion Diseases Ppt
Onion diseases can affect the quality and yield of an onion crop. Causes of onion diseases can include pests, environmental conditions, improper agricultural practices, and soil-borne pathogens.
Common onion diseases include Fusarium wilt, bacterial soft rot, and white rot. Prevention and control methods include crop rotation, good sanitation practices, use of disease-resistant varieties, and fungicides.
Onion Fungal Diseases
Onion fungal diseases are caused by a variety of different fungi that attack onion plants. These diseases can cause stunted growth, leaf discoloration, and reduced yields.
Common onion fungal diseases include white rot, purple blotch, and downy mildew. Proper cultural practices such as crop rotation, avoiding overcrowding, and proper irrigation can help to prevent and manage onion fungal diseases. Chemical fungicides may also be used to control these diseases.
Conclusion
Onion farms are vulnerable to a range of diseases, including damping off, bacterial soft rot, Stemphylium leaf blot, purple blotch, Fusarium basal rot, and Alternaria leaf blight. To reduce the risk of disease, you should practice crop rotation, use disease-resistant varieties, and monitor your fields regularly. Also, treatments such as fungicides, insecticides, and manure can be used to treat infected crops.
