What to Do for Blight on Tomato Plants?

What To Do For Blight on Tomato Plants?

Tomato blight requires immediate and multi-faceted action: remove and destroy infected foliage, apply copper-based fungicides preventatively, and ensure proper air circulation and soil health to minimize future outbreaks.

Understanding Tomato Blight

Tomato blight, a devastating fungal disease, can quickly decimate tomato plants, robbing gardeners of their prized harvest. Understanding its causes, symptoms, and management strategies is crucial for successful tomato cultivation. Blight isn’t a single disease, but rather a term often used to describe several fungal diseases affecting tomatoes, primarily early blight and late blight. Early blight, caused by Alternaria solani, is typically less aggressive than late blight. Late blight, caused by Phytophthora infestans, the same culprit behind the Irish potato famine, can rapidly destroy entire crops under cool, wet conditions.

Identifying Blight Symptoms

Early detection is key to managing blight effectively. Learn to recognize the telltale signs of both early and late blight:

• Early Blight:

  • Small, dark brown spots on lower leaves, often with concentric rings resembling a target.
  • Yellowing of the tissue surrounding the spots.
  • Spots enlarge and coalesce, leading to defoliation.
  • Fruit may develop dark, sunken lesions near the stem end.

• Late Blight:

  • Water-soaked, light green to brown lesions on leaves, often starting at the leaf tips or edges.
  • White, fuzzy growth (sporangia) on the underside of leaves during humid conditions.
  • Rapid spread and collapse of entire plants.
  • Fruit develops large, greasy-looking brown blotches.

Prevention is Paramount

Preventing blight is always easier than curing it. Implementing these preventative measures can significantly reduce the risk of infection:

• Choose Resistant Varieties: Select tomato varieties bred for blight resistance.
• Start with Disease-Free Seedlings: Purchase seedlings from reputable sources or start your own from certified disease-free seeds.
• Practice Crop Rotation: Avoid planting tomatoes in the same location year after year. Rotate with unrelated crops like legumes or brassicas.
• Provide Adequate Spacing: Proper spacing between plants allows for good air circulation, which reduces humidity and inhibits fungal growth.
• Water Carefully: Water at the base of the plants to avoid wetting the foliage. Drip irrigation or soaker hoses are ideal.
• Mulch Around Plants: Mulch helps to prevent soilborne pathogens from splashing onto the leaves.
• Maintain Soil Health: Healthy plants are more resistant to disease. Amend the soil with compost and other organic matter to improve drainage and fertility.
• Remove Suckers: Prune suckers (small shoots that grow between the main stem and branches) to improve air circulation and reduce humidity.

Treatment Strategies Once Blight Strikes

Even with the best preventative measures, blight can still occur. If you spot signs of blight, act quickly:

1. Remove Infected Foliage: Prune away any leaves or stems showing signs of blight. Dispose of the infected material in the trash or burn it – do not compost it, as the fungus can survive in compost.
2. Apply Fungicides: Copper-based fungicides are effective against both early and late blight. Apply according to the manufacturer’s instructions, paying close attention to re-application intervals, especially after rain. Other options include chlorothalonil or mancozeb-based fungicides for more severe infections, always consulting and adhering to label instructions.
3. Improve Air Circulation: Prune plants further to improve air circulation and reduce humidity. Consider staking or caging plants to keep them off the ground.
4. Monitor Plants Closely: Check plants daily for new signs of infection. Continue to remove infected foliage and reapply fungicides as needed.
5. Consider Harvesting Remaining Fruit: If the plant is severely infected and unlikely to recover, harvest any mature or nearly mature fruit. Green tomatoes can be ripened indoors.

Choosing the Right Fungicide

The selection of a fungicide depends on the type of blight and the severity of the infection.

Common Mistakes to Avoid

• Composting Infected Material: This can spread the disease.
• Overwatering: Wet foliage encourages fungal growth.
• Ignoring Early Signs: Early detection is crucial for successful treatment.
• Using Homemade Remedies Without Testing: Some homemade remedies can be ineffective or even harmful to plants.
• Planting Tomatoes in the Same Spot Every Year: This allows soilborne pathogens to build up.
• Failing to Read and Follow Fungicide Labels: Improper application can be ineffective or even harmful.

Frequently Asked Questions (FAQs)

What exactly is the difference between early blight and late blight?

Early blight is caused by the fungus Alternaria solani and typically starts on the lower leaves with target-like spots, progressing more slowly. Late blight, caused by Phytophthora infestans, spreads rapidly, creating water-soaked lesions and fuzzy white growth, and can devastate entire plants quickly.

Can I eat tomatoes from a plant with blight?

It depends on the severity of the blight and the specific symptoms on the fruit. If the fruit shows signs of blight (dark, sunken lesions or greasy blotches), it is best to discard it. Tomatoes without obvious symptoms can be harvested and consumed, but wash them thoroughly.

How often should I apply fungicide to my tomato plants?

The application frequency depends on the fungicide and weather conditions. Generally, copper-based fungicides need to be reapplied every 7-10 days, or more frequently after rain. Always follow the manufacturer’s instructions on the product label.

Will removing infected leaves cure my tomato plant of blight?

Removing infected leaves can help slow the spread of the disease, but it is unlikely to cure the plant completely. Blight is a systemic disease, meaning it can spread throughout the plant’s vascular system. Removing infected leaves must be combined with fungicide applications and other preventative measures.

What are some tomato varieties that are resistant to blight?

Some tomato varieties with reported blight resistance include ‘Mountain Magic’, ‘Defiant PHR’, ‘Legend’, and some hybrid varieties bred specifically for disease resistance. Check seed catalogs and local nurseries for available varieties that are well-suited to your region.

Is there an organic way to treat tomato blight?

Copper-based fungicides are generally considered an organic option for managing tomato blight. Other organic approaches include improving soil health, ensuring good air circulation, and removing infected foliage promptly. Biofungicides may also offer some protection.

How can I prevent blight from spreading to my other plants?

• Remove infected plants immediately.
• Improve air circulation.
• Avoid overhead watering.
• Apply preventative fungicides.
• Clean tools after using them on infected plants.

Can blight survive in the soil?

Yes, early blight can survive in the soil for several years, especially on tomato debris. Late blight, however, usually doesn’t survive in the soil long-term, relying on infected plant material or seed potatoes. Practicing crop rotation and removing plant debris can help reduce the risk of soilborne blight.

What causes blight to be worse in some years than others?

Weather conditions play a significant role. Cool, wet weather favors the spread of late blight, while warm, humid weather encourages early blight. Also, the presence of infected plants nearby can increase the risk of blight outbreaks.

Can I save seeds from my tomato plants if they had blight?

It’s generally not recommended to save seeds from tomato plants that showed signs of blight, as the seeds may be contaminated with the fungal spores. Using certified disease-free seeds is a safer option.

My tomato plant has blight, but I have lots of green tomatoes on it. Can I ripen them indoors?

Yes, you can harvest green tomatoes from a blighted plant and ripen them indoors. Place the tomatoes in a paper bag with a ripe banana or apple, which will release ethylene gas and speed up the ripening process. Regularly check the tomatoes and remove any that show signs of rot.

Should I completely destroy my tomato plants if they are infected with late blight?

If your tomato plants are severely infected with late blight and showing rapid decline, it’s generally best to remove and destroy them to prevent the disease from spreading to other plants in your garden or community. Proper disposal, like burning or bagging and discarding as trash, is vital.

Ready to Level Up Your Cooking? Watch This Now!