Late Blight in Tomato: A Comprehensive Guide for Symptoms, Treatment and Prevention

• June 28 2023, by Agriplex India
• 7 min reading time

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Late blight, caused by the pathogenic oomycete Phytophthora infestans, is a devastating disease that affects tomato plants worldwide. This aggressive fungal-like pathogen can rapidly spread, leading to significant yield losses in both commercial and home gardens. Understanding the symptoms, implementing effective treatment methods, and employing preventive control measures are crucial for managing late blight and preserving tomato crops. In this article, we will delve into the symptoms exhibited by infected plants, explore treatment options, and discuss preventive measures that can aid in mitigating the impact of late blight.

Symptoms of Late Blight in Tomato

Detecting the symptoms of late blight in tomato plants is essential for timely intervention. The disease typically affects all above-ground parts of the plant. Initially, small, water-soaked lesions appear on leaves, which gradually enlarge and develop a pale green to grayish-brown color. These lesions may exhibit a velvety texture and become surrounded by a characteristic white mold during periods of high humidity. Infected leaves eventually wither and die.

As late blight progresses, dark brown to black lesions can also appear on tomato stems. The pathogen can rapidly spread to fruits, resulting in large, irregularly shaped, and firm lesions with a dark, greasy appearance. In humid conditions, a fuzzy white mold may appear on the surface of the fruit lesions. The decay can quickly spread throughout the entire fruit, leading to complete rot.

Treatment of Late Blight in Tomato

Once late blight is identified, prompt treatment is vital to minimize the disease's impact. Here are some effective methods for managing late blight in tomatoes:

• Fungicides: Several fungicides, including copper-based formulations and those containing chlorothalonil or mancozeb, can be used to control late blight. It is essential to follow the product label instructions and apply fungicides preventively or at the first sign of disease. Regular and thorough coverage of all plant parts is crucial for effective control.
• Cultural Practices: Implementing good cultural practices can help reduce the risk of late blight. These include ensuring proper spacing between plants for adequate airflow, practicing crop rotation, and removing and destroying infected plant debris to prevent overwintering of the pathogen.
• Resistant Varieties: Planting tomato varieties that are resistant to late blight can be an effective preventive measure. Consult local agricultural extension services or reputable seed suppliers for recommendations on resistant cultivars suitable for your region.
• Quarantine: If late blight is detected in your garden, isolate and quarantine infected plants to prevent further spread. Avoid transferring infected plant material to other locations, and clean tools thoroughly after use to avoid contamination.
• Sanitation: Practice good sanitation by removing and disposing of any diseased plant material properly. This helps reduce the chances of pathogen survival and recurrence in subsequent seasons.

Preventing Late Blight in Tomato

Prevention is often the best approach when dealing with late blight. By implementing the following measures, you can minimize the risk of infection and protect your tomato plants: 

• Site Selection: Choose a well-drained location with ample sunlight for growing tomatoes. Good air circulation and sufficient sunlight reduce humidity levels, creating an unfavorable environment for late blight development.
• Proper Watering: Avoid overhead irrigation, as wet leaves promote disease development. Instead, use drip irrigation or water at the base of the plants to keep foliage dry.
• Crop Rotation: Rotate tomatoes with non-host crops, such as legumes or grains, to break the disease cycle. Avoid planting tomatoes or other susceptible plants in the same location for consecutive seasons.
• Mulching: Apply organic mulch, such as straw or wood chips, around tomato plants to prevent soil splashing, which can spread the pathogen. Mulch also helps maintain consistent soil moisture.
• Early Blight Management: Early blight, caused by the fungus Alternaria solani, often occurs alongside late blight. Managing early blight through cultural practices and fungicide application can help reduce stress on the plants, making them less susceptible to late blight.
• Regular Inspection: Routinely inspect tomato plants for early signs of late blight. Prompt detection enables immediate action, minimizing the disease's impact.
• Weather Monitoring: Monitor weather conditions in your area, as late blight thrives in cool and wet conditions. By staying informed, you can anticipate periods of high disease risk and take preventive measures accordingly.

Protect your tomato crop and buy the best Fungicide online at Agriplex

Here are the top Fungicides used in Tomato Crops against late blight

Product Name	Technical	Dosage
UPl Saaf Fungicide	Mancozeb 63% + Carbendazim 12% Wp	300 gm/ 200 Litre water
Bayer Nativo Fungicide	Tebuconazole + Trifloxystrobin 75 WG(50% +25% W/W)	0.5 gm per liter of water
BASF Systiva Fungicide	Fluxapyroxad 33.3% w/v	1 ml/kg seeds
Syngenta Ridomil Gold	Metalaxyl 4% + Mancozeb 64%	1-1.5 gm/ liter of water.
BASF Xelora Fungicide	Thiophanate Methyl 45%+ Pyraclostrobin 5% FS	1.0-1.2 Liter per ha
Bayer EverGol Fungicide	Penflufen 13.28% W/W + Trifloxystrobin 13.28% W/W	8 ml/kg of seed
BASF Acrobat Fungicide	Dimethomorph 50% WP
Syngenta Amistar Fungicide	Azoxystrobin 23%SC	0.5 to 1ml/liter of water
Bayer Buonos Fungicide	Tebuconazole 38.39% SC	250ml/acre.
Dhanuka Lustre Fungicide	Flusilazole 12.5% + Carbendazim 25% Se	384-400ml per Acre
Bayer Infinito Fungicide	Fluopicolide 5.56% Ww + Propamocarb Hydrochloride 55.6% Ww	2.5-3ml per liter of water
Crystal Blue Copper Fungicide	Copper Oxychloride 50wp	1- 2 gm/ ltr of water
Bayer Antracol Fungicide	Propineb 70% WP	3gm per liter of water
Multiplex Neel Cu	Copper EDTA 12%	0.5 g per liter
Syngenta Amistar Top Fungicide	Azoxystrobin 18.2% + Difenoconazole 11.4% SC	200 ml / acre

Conclusion

Late blight is a significant threat to tomato crops, but with vigilant monitoring, timely treatment, and proactive preventive measures, its impact can be minimized. Recognizing the symptoms, employing appropriate treatment options, and implementing effective control measures will help protect your tomato plants and ensure a successful harvest. By adopting a holistic approach to managing late blight, gardeners and farmers can mitigate the disease's impact and maintain healthy tomato crops for years to come.

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Agriculture Blogs Gallery Diseases Late Blight Tomato

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