Bacterial Speck is a Common Tomato Disease

There are many types of diseases that can infest your tomato plant and cause the tomato to rot or wilt prematurely. Tomatoes are susceptible to diseases and bacteria just like people are and it can have devastating long-term effects on the tomato plant. Bacterial speck is just one of the many various diseases that can harm your tomato plant and cause the whole crop to die or become physically damaged. Bacterial speck found on a tomato is very distinguishable by the unique physical symptoms. In order to make sure you do not have a tomato crop infected with bacterial speck you need to know what it is and how to prevent or treat the disease.

Bacterial speck in a tomato is a disease that often harms the fresh-market production of tomato crops. Bacterial speck is a bacterial infection that occurs on a tomato and it shows physical symptoms such as a change in appearance. Bacterial speck will look similar to a necrotizing disease that affects people which means it will appear like an area of the tomato is dead or decaying. A tomato infested with bacterial speck will often show speck lesions which are more noticeable on a green tomato. The bacterial speck will show up as small black spots that are sunken in and it will have a dark green circle around it. If you have a ripe tomato then the spots will appear black or very dark brown and will be superficial in nature. The bacterial speck is very hard to differentiate from another tomato disease if it occurs on the foliage. You might see small leaf spots that have black lesions with a yellow halo around the outside. If the foliage is infected with the bacterial speck you also might notice that the dark brown or black spots appear like an oval on the tomato. The halo will be the first thing you will notice because it is quite large in nature and usually is about twice the size of the bacterial speck itself.

Bacterial speck is a tomato disease that often favors certain environments so it is important to know what type of environment it will mostly occur in. Bacterial speck will be seen predominantly in cooler environments that are moist and humid. The bacterial speck will grow rapidly in temperatures over 75 degrees Fahrenheit which is the perfect temperature for bacterial growth. The bacterial speck is spread by mechanical means and is also spread by wind and rain. Since bacterial speck grows rapidly in wet and cool conditions, the longer a tomato is exposed to wetness the greater chance it has of developing the disease. Even just one day of hard rain in a location where the tomato grows is enough for the bacterial speck to form and start infesting the whole tomato crop. In order to keep your tomato from getting bacterial speck you need to know what type of management and prevention you can do before it happens.

The residue of a tomato should be discarded and not left in the soil to prevent the growth of the bacterial speck. Bacterial speck has a limited host range which means you should avoid double-cropping your tomatoes to help control and prevent the disease. There are no chemical treatments on the market to specifically get rid of bacterial speck or prevent the infestation of the disease on your tomato plant. You might be able to control the growth of bacterial speck by applying bacterial spot pesticide control if you want to use a chemical option. Copper tank mixed with Mancozeb have been used before in the prevention and control of bacterial speck but it is not guaranteed to help the tomato plant. The most important thing you can do to prevent or control bacterial speck on your tomato is to limit the amount of wetness and cool weather that the tomato gets. Since bacteria grow in the moist and damp environments, it is best to try to keep your tomato out of that situation as much as possible.

Ken Pernezny and Shouan Zhang, "Bacterial Speck of Tomato", University of Florida, Institute of Food and Agricultural Sciences, Florida A. & M. University