Cilantro, or coriander, is a great herb that can add a nice aroma and presentation to your herbal garden without demanding too much care. Not only this, cilantro also attracts beneficial insects to your garden. Being non-toxic, it is a great addition to your pet-friendly garden. But like other plants, cilantro is also susceptible to pests and diseases. In this article, we will discuss common cilantro (coriander) pests and diseases, symptoms and control tips. You will learn about common bacterial, viral, and fungal diseases of cilantro as well as pests. Plus, you’ll learn how to keep the pests away from your coriander plants.
The most common diseases of cilantro (coriander) include bacterial blight, soft rot, Carrot Motley Dwarf disease, powdery mildew, damping off. Common pests in cilantro include aphids, beet armyworm – cilantro often repels spider mites due to its scent (but if you notice webbing and black/red spots on leaves, it might be spider mites).
Bacterial diseases of cilantro
Coriander (Coriandrum sativum) is a herb that can survive only for one growing season. It reaches a height of around 1-1.6 feet (30-50 cm). Most bacterial diseases of cilantro are ones seen in field crops. However, some of these diseases also affect homegrown herbs.
The most common bacterial diseases of cilantro are discussed below.
Cilantro (coriander) bacterial blight
Bacterial blight is the most serious diseases in coriander plants. It commonly occurs in both outdoor and pot-grown plants. Infected cilantro plants can’t be consumed or marketed.
Causes: It is caused by the bacterium Pseudomonas syringe, which is transmitted through infected seeds. The disease spreads from one plant to another by pollinator insects, splashing rain or irrigation water, movement of machinery.
Symptoms:
- Black to brown necrotic spots on all cilantro plant parts with water-soaked margins.
- Angular spots on both sides of the leaves.
- Infected seeds fail to germinate.
- Lesions on the stem cause the infected flowers and petals to collapse.
- The infected inflorescence appears blighted initially by turning yellow, and then brown.
- Unripe green fruit becomes dark and shriveled.
Control:
Severe bacterial blight is difficult to control. A few preventive measures can be taken to control the spread of disease.
- Make sure to use healthy tested seeds that meet the seed health standards.
- Treating seeds with hot water at a temperature of 260 F (127 degrees Celsius).
- Disinfect gardening equipment or tools after harvesting/cutting coriander.
- Don’t use overhead irrigation as it promotes disease spread.
- For gardens, use a sterile potting mix for growing cilantro to avoid this problem
Soft Rot
Bacterial soft rot is highly responsible for destroying cilantro plants throughout the world. The bacteria attack the petioles and other fleshy organs, destroying the whole plant. The bacteria grow at high temperatures of 70–80 °F (21-27 C). Moreover, high humidity levels are another main reason for the spread and growth of soft rot.
Causes: The bacteria named Erwinia carotovora, Erwinia chrysanthemi, Pseudomonas marginalis are the main cause of bacterial soft rot in cilantro.
These bacteria enter the plant through exposed or damaged tissues, and wounds. It spreads through uncleaned garden tools and infected plant debris or soil. The insects also carry the disease from infected plants to healthy plants.
Symptoms:
- Small water-soaked spots appear at the base of petioles.
- These spots cause the soft tissues to become mushy and brown.
- The petioles of cilantro start to rot (with a bad smell).
Control:
Soft rot is hard to control. It has no treatment. You can take measures to prevent this disease of cilantro in the future.
- Remove the infected plant parts as soon as you can.
- Don’t add the infected plant parts to compost.
- Avoid overcrowding the plants. Ensure wide spacing between plants for good ventilation (8-10″/20-25 cm between each cilantro).
- Don’t damage plants during weeding or transplanting.
- Grow cilantro in well-drained soil.
- Avoid overwatering and allow the plants to dry before each watering.
- Disinfect garden tools by rubbing 10% bleach and 70% alcohol before and after harvest.
Viral diseases in cilantro (coriander)
Viruses are submicroscopic organisms that replicate in plants and cause considerable damage. When a virus enters a plant, it takes control of the plant and keeps multiplying. The common viral diseases of cilantro are:
Carrot Motley Dwarf Disease (CMDD)
CMDD is caused by the carrot redleaf virus (CRLV) and carrot mottle virus (CMV). Both of these viruses are transmitted by Willow carrot aphids from plant to plant. The cilantro plant is not a host of this aphid. Carrot plants are the main hosts of both of these viruses.
Symptoms:
- Severely stunted seedling growth.
- The infected leaves on cilantro turn orange, yellow, and red.
Control:
- Don’t plant cilantro close to overwintered carrots.
- Plant coriander in soil that has no previous history of this disease.
- Take steps to control carrot willow aphids.
Fungal diseases in cilantro (coriander)
Fungi are the plant pathogens that decompose the plant remains and feed on them. High humidity levels, overcrowded plants, overwatering, and high temperature provide an ideal medium for fungal growth in cilantro plants. The common fungal diseases of cilantro (coriander) are:
Powdery Mildew
Powdery mildew is the most common fungal disease of cilantro. The fungus affects the overall coriander production and changes the flavor of leaves. The cilantro plant affected with powdery mildew looks like it’s been dusted with baby powder.
Causes:
It is caused by the fungus Erysiphe heraclei. The fungal spores germinate and spread faster when the plant is exposed to moisture for longer periods. Overhead watering also promotes the spread of disease.
Symptoms:
- White coating or fluffy growth on the leaves, petioles, bracts, and flower stalks
- Discoloring of leaves
- Distortion of flowers
- Cilantro plants dropping leaves if untreated
Control:
- Rub the leaves to remove pests in mild cases. Crush some cloves of garlic and dilute them with water. Spray this solution as an organic control of fungus on the cilantro leaves.
- Spray a solution of baking soda mixed with water on the leaves. It prevents fungal growth by altering the pH of leaves.
- Use sulfur foliar spray every 7 to 14 days on the cilantro leaves.
- Spray leaves with organic neem oil solution like this. Neem oil is one of the best natural remedies for a wide range of pests and fungal infections.
- Use drip irrigation to water the roots. Avoid wetting the foliage during watering.
- If every solution fails, destroy the affected leaves. Plant new cilantro as it grows rather quickly.
- Grow coriander in a sunny spot. The fungal spores and mycelium are sensitive to sunlight.
Damping-off in cilantro (coriander)
Damping-off is a fungal disease of cilantro, that mainly attacks seeds and newly germinated plants. It is the most common problem in indoor seed raising. The spores of this fungus are present in almost every type of soil.
On a commercial level, growers prefer to sterilize the soil before planting cilantro with heat and chemicals. However, home gardeners can avoid this problem by taking precautions to avoid the growth of this fungus.
Causes:
It is caused by the fungus Pythium spp. Rhizoctonia solani. High humidity levels and overcrowded seeds allow the growth of the spores of this fungus. One of the main causes of damping-off is overwatering cilantro on days with low sunlight, leading to the soil not drying up properly. Also, it spreads with contaminated water and equipment.
Symptoms:
- Water-soaked red spots on the stem of newly emerging seedlings.
- Seeds become rotten and fail to germinate. Or, apparently healthy cilantro seedlings suddenly start collapsing.
- The roots rot, causing the plant to become yellow and die.
Control:
- Use high-quality coriander seeds for planting.
- Plant seeds in well-drained soil.
- Avoid overwatering and overcrowding the plants.
- Disinfect all the garden equipment.
- Seaweed tea or chamomile tea also helps in preventing the spread of fungus on small areas of plants.
- Allow good air exchange.
Common pests of cilantro (coriander)
The insects that damage plant parts by feeding on them are considered pests. Different insects cause different symptoms in cilantro plants. By identifying these pests, you can start getting rid of the problem. Besides, you can learn the causes and prevent or reduce infestation by maintaining good horticultural practices in the future.
The common pest insects of cilantro plants are:
Aphids in cilantro (coriander)
Aphids are soft small-bodied insects that feed on the sap of plants. Willow-carrot aphids (Cavariella aegopodii) are highly problematic for cilantro plants. That’s because they are responsible for spreading plant viruses – carrot mottle virus (CMV) and Carrot Redleaf Virus (CRLV). Carrot plants are the hosts of these viruses and cilantro plants grown near overwintered carrots are at a high risk of willow carrot infestations.
Symptoms:
- Small dark spots on leaves, which might look like streaks too.
- Stunted growth of new shoots
- Necrotic spots on leaves
- Yellowing and browning of leaves
- Aphids secrete honeydew that causes sooty mold growth on infested plant parts.
Control:
- If infestation is at an early stage, prune affected parts of the cilantro plant.
- You can spray the plants with a dependable pressure washer if an infestation is mild.
- Spray neem oil, canola oil, or insecticidal soap like this for mild-moderate infestation.
- Silver-colored reflective mulch is effective for deterring aphids.
- Plant pest-resistant varieties of coriander seeds if everything fails.
Beet armyworm in cilantro (coriander)
Beet armyworms are brown-colored moths ranging from ½ to ¾ inches in size (might notice their larvae/caterpillars). The population of moths increase during warm weather, and attack the cilantro plants during late summer and fall. Beet armyworm contaminates leaves of cilantro and reduces its marketability,
Symptoms:
- Large larvae feed on the petioles
- Stunted growth on developing buds
- Closely grouped irregularly shaped holes on the leaves.
Control:
- Hand-pick caterpillars
- Apply neem oil if you notice larvae, or cottonseed oil if eggs/larvae.
- Spray Bacillus thuringiensis, a naturally occurring bacterium that produces toxins to kill the beet armyworm.
Conclusion
Fortunately, the strong scent of cilantro plants keeps most of the pests away. However, the most common diseases of cilantro are fungal diseases. You can avoid them by planting cilantro in a sunny spot in well-drained soil. Make sure to solve the problem by properly identifying the reason first.
Avoid using chemical sprays on your cilantro plants as you will be consuming them. Always use natural controls against cilantro pests, such as insecticidal soap, neem oil, and horticultural oil. And if you don’t get to manage the problem, start with a new plant.
To read more about cilantro growing and care tips, visit this page.