What to do About Bacterial Speck

Many Missouri tomato producers have encountered significant problems with bacterial speck this year. Bacterial diseases have become increasingly more severe with some bacterial races becoming resistant to copper. Speck is more common in cool, wet weather while spot is more likely to occur in warm, wet weather. Management for control of both diseases is similar.

1. Fumigate, steam or soak tomato stakes in a 10% bleach solution for 10 minutes. Bacterial speck/ spot will carry over on stakes. Sterilizing can be done before you stake tomatoes in the spring.
2. Do not save seed from any tomato plants that show symptoms of bacterial speck or spot. Both of these diseases can be seed borne.
3. If you grow your own transplants, make sure the greenhouse is sanitized.
4. Actigard 50WP is currently labeled for control of bacterial speck and spot on tomatoes. Copper sprays will suppress bacterial diseases while Actigard increases plant resistance. Research at the University of Kentucky has indicated a 14 day spray schedule with Actigard provided acceptable disease control.
5. Copper products (Kocide, Bravo C/M) will suppress bacterial diseases. Mixing copper with mancozeb and maneb is particularly effective.
6. Avoid overhead watering.
7. Rogue infected plants.
8. Deep plowing in the fall will bury disease residue.
9. Control weeds such as nightshade and horsenettle in the field and in border areas. Bacterial diseases (and other diseases) can overwinter on these weed species.
10. Rotate out of tomatoes for 2 years.

Bacterial Speck on a Tomato (photo courtesy of North Dakota State University)

Lewis Jett, Assistant Professor & State Vegetable Crops Specialist, UMC (573) 884-3287