A major problem in tomatoes, target spot can be easily misdiagnosed in its early stages and is often confused with bacterial spot and early blight. The pathogen, Corynespora cassiicola, has a wide range of hosts and can survive in crop debris for up to two years. Its spores are primarily spread through the air in midmorning at air temperatures around 82 degrees.
Growers are reporting more difficulty managing target spot in tomatoes due to dependence on strobilurin fungicides. With any disease-control program, one of the best ways to avoid resistance development is to alternate modes of action during the season.
Identifying Target Spot
- Lesions with bull’s-eye appearance
- Small, brown, sunken flecks in early stages
- As disease matures, legions coalesce
- Advanced stages show visible fungal growth in center of lesions
Timing Is Everything
A timely fungicide application prior to infection is the best way to control target spot. We recommend an application of DuPont™ Fontelis® fungicide at 16 to 24 fluid ounces per acre. Fontelis® can be applied at 7- to 14-day intervals, depending on disease pressure. It provides excellent crop safety and is rainfast within one hour of application.
In addition to the above fungicide application, now is the time to review cultural best practices with growers. The University of Florida IFAS Extension specialists recommend using the following steps to reduce disease pressure in tomatoes and other cucurbits:
- Use plastic mulch to help control fruit rot
- Eliminate volunteer plants and rotate crops to reduce pathogen carryover between seasons
- Increase soil pH with lime applications, especially on sandy soils
- Avoid excessive plant handling, especially when plants are wet
- Sanitize stakes and decontaminate equipment before moving to another field
Always read and follow all label directions and precautions for use. DuPont™ Fontelis® is not available in all states. See your local DuPont sales representative or retailer for details on availability. Unless indicated, trademarks with ®, ™ or ℠ are trademarks of DuPont or affiliates. © 2016 DuPont