How to Prevent and Control Late Blight in Tomato

Tomato blight, particularly late blight, is one of the serious diseases affecting tomato farming in Kenya. It is a fungal disease caused by a pathogen called Phytophthora infestans. The disease is more common during the rainy season due to the wet and humid conditions that favor the development of the pathogen. 

Tomato Late Blight: in Kenya, it is common during the rainy season

Here’s how you can prevent, manage and control tomato blight effectively:

1. Start With Preventative Measures

• Choose Resistant Varieties: Plant hybrid tomato varieties that are resistant to blight. From experience, Harmony, Ansal, Terminator, and Nyanya F1 are some of the best varieties available in Kenya in this regard. 
• Use Certified Seedlings: I would have said seeds but I know farmers nowadays prefer buying ready-to-plant seedlings. Contact Richfarm Kenya on 0724698357 / 0723213602 in order to buy certified, high-quality tomato seedlings. They will deliver to you any where. 
• Crop Rotation: Do not plant tomatoes on the same plot for 2 consecutive seasons. Rotate tomatoes with non-solanaceous crops like beans, peas or maize. This helps to reduce the build-up of blight-causing organisms in your soils.

2. Follow Good Agronomic Practices

• Proper Spacing: We recommend the standard spacing of 1m between the rows and 0.5m from plant to plant. This helps to improve air circulation, reducing humidity around the plants, therefore reducing the risk of developing tomato blight. 
• Pruning: Remove all the lower leaves and excess branches. Like proper spacing, this practice helps to improve airflow and reduce the spread of the tomato blight.
• Avoid Overhead Irrigation: If you must irrigate your tomatoes, please strive to use drip or flood irrigation methods: avoid sprinklers at all cost. The reason why tomato late blight is more prevalent during the rainy season is because the organisms causing it thrive in wet conditions.
• Mulching: Use dry plant matter or the commercial plastic mulch to reduce soil splashing onto leaves and help maintain soil moisture.

3. Observe Top-notch Cleanliness 

• Remove Infected Plants: Uproot and burn all the plants showing signs of blight. You better lose a few plants than damage the entire farm. 
• Clean Your Farm Tools: Treat your tools regularly with disinfectants to avoid transmitting the disease. Spray all your staking sticks before using them the next season. 
• Weed Management: Well, why would any serious tomato farmer in Kenya even be reminded of this? I am just insisting on the importance of keeping your farm free from weeds. Weeds can host the pathogens that cause late blight in tomatoes, and they also  increase humidity in the field hence creating a favourable environment for the spread of the disease.

4. Chemical Control

• Preventive Fungicides: Apply fungicides containing copper or mancozeb starting early; immediately after transplanting. some of the brands available in Kenya are: TRINITY GOLD 452 WP at 50g in 20L of water, ABSOLUTE STAR 400 SC at 10ml in 20L of water, TOWER EXTREME 680 WG at 50g in 20L of water. There are many other brands: all you need to ensure is that they have copper or Mancozeb as the active ingredient.

• Systemic Fungicides: If your crops have already been affected, use systemic fungicides to treat them. These are the fungicides containing metalaxyl or propamocarb as the active infections. I also recommend that you have 2 types of fungicides so that you use them interchangeably to avoid the disease from building up resistance.
• Frequency of Spraying: During the rainy seasons, spray once every 7–10 days. Spray once a week during if already infected.

5. Alternative Biological Control

My honest opinion of this method is that it is only suitable for small gardens. For commercial tomato farming in Kenya, I suggest sticking to the chemical control methods. However, the biological control methods available for tomato late blight are: 

• Trichoderma spp.:  Trichoderma is an active component in bio-fungicides that acts to suppress the blight pathogen. It is sprayed in crops or drenched into the soil. 
• Neem Oil and Extracts: It's application is similar to that of Trichoderma. Be careful not to cook your tomatoes by applying too much oil on the leaves that the stomata are blocked. 

6. Constantly Monitor Your Farm for Early Detection

• Tomato farming calls for a lot of dedication to the process. You must ensure that you inspect your plants regularly; everyday if possible. This will help you reduce losses by dealing with the challenge at its first signs; (dark, water-soaked spots on leaves or stems).
• Act immediately by removing infected plants and applying fungicides as directed above.

7. Post-Harvest Hygiene

• Clean up all plant remains after harvest and dispose of them away from the farm. You would better invest in proper manure than risking. 
• Do not use infected plant material to make compost manure since the pathogens will be carried on to your farm when you apply such compost.

Integrated Approach

Instead of relying on chemical control like most farmers do, I recommend combining these strategies.  We are also ever ready to help you whenever you have challenges. You can always reach us on 0724698357 / 0723213602. 

Read Also:

Tomato Farming in Kenya: How To Do It Without Burning Your Fingers

Everyone knows someone who has made millions with in tomato farming but they also know many others who have lost terribly while at it. What makes the difference is...