Row by Row Episode 138: The Best Way to Control Tomato Diseases

Controlling Tomato Diseases

There are a couple of different tomato diseases that can be very hard to control in the vegetable garden. However, if you know what causes these diseases and the symptoms behind them you can have better success with controlling and treating these pesky diseases. Depending on where you live you may experience more issues with certain diseases than somebody in a different area or zone.

Bacterial Wilt (aka Southern Bacterial Blight)

The main cause of bacterial wilt happens usually overnight and takes out two or three plants. This is a bacterial soil-borne disease that will happen when temperatures are humid and wet. One way to avoid bacterial wilt is by planting disease-resistant varieties such as Invincible. Another way to decrease your chance of avoiding this virus is to have at least a 3-year crop rotation. By implementing crop rotation in your garden you not only improve your soil health but also improve your chances of not dealing with these soil-borne tomato diseases. You should also remove crop debris as soon as those tomato plants are done producing. The quicker you remove all the crop debris from the area the faster those soil-borne diseases will be eliminated in the vegetable garden.

Early Blight

One of the more common tomato diseases that we hear a lot about is early blight. Early blight is caused by fungi that live in the soil and will start up when temperatures become hot and wet. You can identify early blight by looking for brown circular lesions on older foliage and yellowing of the plant tissue as well. The best way to treat early blight is to use drip irrigation to reduce leaf moisture, fertilize monthly with Calcium Nitrate, and treat plants with Mancozeb or Liquid Copper Fungicide.

Late Blight

Similar to early blight, late blight is also caused by fungi that live in the soil. However, late blight is triggered when temperatures become cooler and wetter in the vegetable garden. You can identify late blight on plants when dark and water-soaked spots pop-up on the tomato leaves. Once these spots become visible on the plants soon after the leaves will begin to fall off. The only late blight disease-resistant variety we have available is Invincible Tomato which is a determinate paste variety. Treating both early blight and late blight is very similar, you will need to use drip irrigation, remove crop debris, and use Liquid Copper Fungicide to help control this tomato disease. Also, the most common host for late blight is potatoes, therefore you need to have at least a 3 to 4-year crop rotation so you can avoid planting tomatoes after potatoes.

Septoria Leaf Spot (Gray Leaf Spot)

Septoria Leaf Spot is also known as Gray Leaf Spot is another fungal tomato disease. In order to identify gray leaf spot, the leaves will start forming tiny black specks or small circular spots with dark borders and a beige center. This tomato disease becomes problematic when temperatures reach 68 to 77 degrees and high humidity or heavy leaf moisture. We have several disease-resistant varieties such as Bella Rosa, Red Snapper, Summerpick, Mountain Vineyard, Big Beef, Florida 91, Invincible, Southern Ripe, Roadster, Jolene, Chef’s Choice Pink, and Lemon Boy Tomato. Even though these varieties all have disease-resistance to gray leaf spot it does not mean they are 100% susceptible to getting this tomato disease.

Tomato Spotted Wilt Virus

When it comes to Tomato Spotted Wilt Virus this is spread by thrips that feed on the weeds in the garden. Once one plant gets this wilt virus it spreads quickly and spraying treatment is almost ineffective. Once the plants are infected they will be stunted with bronze or dark spots/purple veins. While the upper foliage will be twisted and cupped with yellow spots on fruits. Like other tomato diseases, the best way to treat this virus is by planting disease-resistant varieties like Bella Rosa, Red Snapper, Summerpick, Tachi, Mountain Vineyard, Southern Ripe, and Roadster. You can also deduce tomato spotted wilt virus by keeping weeds to a minimum throughout the year since they do harbor the virus.

Tomato Yellow Leaf Curl Virus

Another viral disease is the Tomato Yellow Leaf Curl Virus which is transmitted by whiteflies that feed on weeds and other infected plants in the vegetable garden. Once your leaves begin to curl up and turn yellow it’s usually a tell-tell sign that your plants are experiencing tomato yellow leaf curl virus. In order to avoid this tomato disease, you can plant disease-resistant varieties such as Summerpick, Red Snapper, and Jolene. You can’t spray for this disease, but you can apply Horticulture Oil or Canola Oil to reduce whitefly feeding in the garden.

Tobacco Mosaic Virus

The Tobacco Mosaic Virus is transmitted through tobacco use and by aphids, whiteflies, and leafhoppers. The tomato leaves will become light or dark green with mottling surrounding the leaves. The disease-resistant varieties for tobacco mosaic virus are Celebration, Celebrity, Big Beef, Purple Boy, and Chef’s Choice Orange Tomato. You should once again keep weeds to the bare minimum in order to reduce this disease pressure.

Root-Knot Nematode

Another common tomato issue is root-knot nematode which is classified as a disease as well. You will know if you have root-knot nematode problems if you pull your plant out of the soil and root galls are surrounding the roots of your plants. There are several disease-resistant varieties available such as Summerpick, Tachi, Celebrity, Better Boy, Southern Ripe, Chef’s Choice Pink, Lemon Boy, and Purple Boy. The best way to treat root-knot nematodes is through biofumigation using Kodiak Brown Mustard and interplanting marigolds since they have some nematode suppression properties.

Show and Tell Segment

On the show and tell segment this week, Greg and Travis talk a little bit about the new grow light kits that are excellent for indoor seed starting or growing your own food at a smaller scale. Travis shows off a few pepper transplants that he recently stepped up into larger trays. The guys also discuss a few new varieties that have been added to the site now. The first new variety is Impatiens Camelia Mix which is an heirloom flower mix that contains rose, salmon, white, scarlet, and violet double blooms. Another new variety is the Bloomsdale Spinach which is an older heirloom variety that dates back to the 1920s. This spinach produces dark-green crinkled leaves that are great for the summer garden because of heat-tolerance. The next new variety is the Kuroda Carrot which is chantenay-type known for its exceptional sweetness and ability to grow well in harder soils. We have a new long day variety of onion, known as the Sterling Onion, that produces colossal or globe-shaped white bulbs in the garden. The last new variety the guys discuss is the Pimento Pepper which is one of the sweeter peppers in the garden that is excellent for stuffing or making pimento cheese.

Viewer Questions

For the Q & A segment this week, the guys answer some viewer questions about freezing corn on the cob and succession planting sweet corn. Greg and Travis prefer to freeze kernels or cream corn due to the overall taste being better and you get more storage room. You can succession plant sweet corn just be sure to have drip irrigation in order to feed the corn during the hotter months in the summer.

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