Tell-tale sign of bacterial spot

Q. The leaves on my pepper plants are turning brown. There are spots all over them. The leaves fall off after a couple of weeks. The bell peppers seem to be more affected. What’s wrong?

Thomas from Hubbard

A. The peppers Thomas brought into the office looked like they had been through the ringer. Many leaves were gone. Others had large, water-soaked lesions that were brown to black on the edges with a hole in the center.

This is a tell-tale sign of bacterial spot.

It is a destructive disease of peppers. The disease can over-winter on plant material in the garden that’s left from last year’s crop. But the most common infections come from contaminated seed.

Many gardeners tend to treat this disease like a fungal disease, spraying fungicide on the plant and wondering why the plants do not improve. This is why it is so important to bring samples to our plant and pest diagnostic clinic for proper identification. Copper and other products can help and reduce spread, but are limited due to the nature of the disease.

This is not a typical year for the disease. The warm, moist summer of 2015 is a more typical year when we see lots of infection from this disease. Thus, we speculate the disease pressure was high and the consistent watering of the garden during the growing season was favorable to the disease.

If you see this disease in your garden, it is most likely coming from the seed. If you are saving seed and growing your own transplants each year, you are most likely contributing to the livelihood of the disease. To stop the reinfection, you need to treat your seeds (and seeds you get from others). There is a process of using either hot water or chlorine to treat your seeds for this bacterial pathogen. To learn the details of these processes, go to: http://go.osu.edu/hotwater.

If you purchased your plants from some other place and have never seen this disease before, it may have come in on the transplants.

When working with peppers and related vegetable crops, there are some basic practices that can limit the spread of this disease:

Wait until after the dew dries before handling plants.

Remove affected plants. Do not put into the compost pile.

Work on a true rotation, with three years of no tomatoes or peppers before planting them again.

For complete details on this disease, including photos, go to: http://go.osu.edu/bacspot

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. Call the office hotline at 330-533-5538 to submit your questions. Regular clinic hours are 9am to noon Mondays and Thursdays.