Growing your tomatoes

County Agent’s Corner



It’s almost tomato time Blount County. As a matter of fact, there are some county-grown, vine-ripe tomatoes here, if you know where to look. Producers that have high tunnels or greenhouse operations are picking ripe tomatoes, and they are good! Of course they may cost a little more, but I am willing to pay for that first tomato sandwich. Field-grown tomatoes usually begin to ripen in late June or the first week of July. Several factors come in to play with tomato ripening, including heating degree units, variety, irrigation, soil fertility, planting date etc. Some folks will plant on raised beds and utilize black plastic, which will also speed the ripening process. Anything that can be done early in the season to provide additional heat to the production system will speed up the process.

To be successful growing tomatoes or any other crop, there are other issues that must be dealt with, including disease and insect pressure. Early blight is a common fungal disease that always visits tomato plants. In wet conditions, the disease will devastate the lower leaves of the plant. A lot of folks will tell me their plants are “firing up” from the bottom. Regular applications of fungicides, especially those containing chlorothalonil as an active ingredient, should prevent or at least slow the progression of the disease. It will also work well on several other fungal disease organisms that attack tomatoes. However, some tomato disease issues are not caused by fungal pathogens, but rather by bacteria. Bacterial spot and bacterial speck are two of these. Products containing copper must be used to prevent or manage bacterial problems in tomato production. ManKocide contains two products, one for bacteria and one for fungal pathogens; this makes it a good product to have on hand if you are growing tomatoes.

Tomato disease issues may also be caused by viruses. Tomato Spotted Wilt Virus (TSWV) is one that can raise havoc in your garden. Thrips, small cigar-shaped insects, pick the virus up from overwintering weed hosts. As they mature, they take flight, and if they get caught up in a wind event, can travel for miles. They light on your tomato plant, begin to feed, and transfer the virus to your plant. The first thing you will notice is your plant is not growing properly. The plant beside it may be twice as big because it didn’t get infected. After a short period of time, you will notice the terminal leaves will begin to turn bronze or black.

Once infected, there is no cure, so it’s best to try to deter thrips with regular insecticide applications early in the season. If your plants do become infected, pull them up and destroy them. I know that is hard to do, but that plant is history. If the fruit are almost ripe at the time of infection, you may harvest those, if you’re lucky. The best way to prevent TSWV is to plant varieties that have resistance. My favorite is Bella Rosa. It is a good garden tomato with heat tolerance, good yields and good flavor. This is just one of several tomato varieties with resistance to this disease.

Abiotic tomato diseases are those caused by something other than living organisms, and may impact your crop. Blossom-end rot (BER) is caused by lack of calcium movement in the plant. The blossom end of the tomato fruit will turn black and eventually rot. This symptom may be seen if the plants are not irrigated or if they are planted in wet areas. It may also be caused due to low soil pH, or the lack of lime (calcium) in the soil. Calcium may not be present in the garden, in enough quantity, to prevent the issue. Most vegetable crops require a soil pH of 6 – 6.5 which means your gardens need lime every three or four years. You can pick up a soil test kit at the Extension office. Knowing what your pH is in the garden is important!

Other abiotic diseases include herbicide injury (which is more common than you would think), graywall, and micronutrient deficiencies. There’s lots of problems that can impact a tomato plant, but if everything goes well, you get a sandwich for the Fourth of July and what could be better than that?

The Farmers Market at the Blount County – Oneonta Agri-Business Center will open on Saturday, June 2. It will be open on Saturdays, Tuesdays, and Thursdays from 7 a.m. until 1 p.m. each day until late October. If other activities are taking place, the market will be moved to the rail bed across from the Agri-Business Center. Produce that may be there this weekend includes locally grown peaches, strawberries, onions, cabbage, squash, lettuce, and other cool season vegetables. It just depends on which producers show up at the market. I think it’s time for a peach pie!

Dan Porch is County Extension Coordinator with the Blount County Extension Office. Dan lives in and loves Blount County and is available to answer your questions about conservation, agriculture, natural resources, and gardening. He can be reached at (205) 274-2129 or