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Each season brings different conditions that can be conducive to blight.  

In a typical year, we tend to see more tomato light blight alerts in late July and August due to cooler nights and longer dew periods. This destructive disease thrives in cool, wet, and humid conditions.  

Sometimes, we see alerts earlier in the season, when seasonal weather patterns and agronomic practices, like overhead irrigation, create conditions for infection before we expect. 

So, what can be done to figure out when tomatoes are at risk for late blight, regardless of calendar date?
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Watch the weather  

• Hazy, misty, foggy mornings are great times to scout for early signs and symptoms of late blight.   
• Tomato late blight is active across a range of temperatures but prefers 15-21°C, in combination with moisture. 
• Learn how to identify blight in tomatoes. 

Leverage available knowledge and data

• What’s happening in your neighbourhood? Late blight is an airborne, community disease. Tap into your network of scouts, agronomists, and crop reports for updates on local conditions. 
• In some regions, disease forecasting models and spore traps are available to help predict late blight outbreaks. Check with your local provincial specialist to determine what models are available for your area.   

 

Use the right tool for the right conditions for tomato late blight:  

Revus (Group 40) is known for its translaminar movement through the leaf and slight systemic movement. Often used earlier in the season or when conditions are conducive for disease development, Revus can be used at 0.24 L/ac with a non-ionic surfactant (0.25% v/v).  


Orondis^® Ultra (Group 40 + 49) is a systemic fungicide that moves into new growth and provides long-lasting control. With two different modes of action, growers tend to choose Orondis Ultra when disease pressure is high, and harvest is imminent. Apply at 0.24 L/ac. 


Bravo^® ZN and Bravo^® ZNC (Group M5) offer proven broad-spectrum control of several diseases, including late blight. At low risk for resistance and with a two-day PHI, apply at 0.9-1.6 L/ac for control of late blight. Please note that directions for use and REI vary by type of tomato grown.

When multiple applications for tomato late blight are required, remember to keep resistance management top of mind by mixing and alternating FRAC Groups, and incorporating multi-site fungicides in the program. multi-site fungicides in the program. 

*Always consult the product label to confirm the application rate and targets by crop. 

Performance evaluations are based on internal trials, field observations and/or public information. Data from multiple locations and years should be consulted whenever possible. Individual results may vary depending on local growing, soil and weather conditions. Always read and follow label directions. Trademarks are property of their respective owners.

Always read and follow label directions. Bravo^®, Orondis^®, Revus^®, Ridomil Gold^® and the Syngenta logo are trademarks of a Syngenta Group Company. All other trademarks are the property of their respective owners.