What is Killing My Tomatoes

Asked July 15, 2013, 6:21 PM EDT

Please see the attached picture and answer what is killing my poor tomato plants. I thought it was just leaf spot, but that only kills the branches on the bottom as far as I know. The entire plant seems to be affected here. Is it fusarium or verticillium wilt?

Wayne County Michigan fruits and vegetables

1 Response

As best as I can tell from the pictures, this appears to be Septoria leaf spot. Septoria leaf spot – The leaf spots of septoria begin as small yellow specks, which later enlarge, becoming brown with a yellow border. They can be either circular or irregular in shape, and often have a black dot in the center. You will see them scattered all over the older leaves of infected tomato plants. Apply copper dust or a liquid copper spray fungicide every 7 to 10 days after discovering the disease until 3 to 4 weeks before harvesting. Control perennial weeds, since they carry this fungus. Remove all plant debris from the garden in fall. Do not work around plants when they are wet. Septoria spores require a high moisture level for germination. Water the plants at ground level rather than overhead to avoid wetting the leaves. In addition water early in the day so plants will dry by evening.

There could also be a flea beetle problem as I see small spots that may be holes caused by the flea beetle. If you find any flea beetles you can control them with an insecticide.

The following are other tomato diseases to be aware of:

Curly top virus – The foliage of seedlings infected with curly top yellows, curls, and twists, and the seedlings usually die. Leaflets of older plants that become infected twist and roll upward, exposing their undersides. The foliage becomes stiff and leathery, and the entire plant assumes a dull yellow appearance. Branches and stems are abnormally erect. Leaf stalks bend downward and the veinsd in the leaflets turn purple. Curly top cannot be cured. Remove and destroy.

Flea beetles - If you find several little holes or perforations in the leaves of your plants, the plants may have flea beetles. Flea beetles are 1/10 inch long, shiny and black, and may have yellow or white markings. They are very active and jump like fleas when disturbed. Their feeding can destroy small plants rapidly.

Early blight – Tomatoes infected by early blight develop collar rot-dark, girdling lesions on the stem at the soil line. The foliage infection appears first as circular or irregular dark spots on older leaves. As these spots enlarge, a series of concentric rings develops, forming a target pattern. Often these spots grow together. Cankers develop of fruit stems, branches and large stems. Green or ripe fruit cracks at the stem. As soon as you spot early blight, begin applying a copper-based fungicide every 7 to 10 days as directed on the label.

Bacterial Spot – The leaves of tomato plants infected with bacterial spot show minute water-soaked areas, which later become angular, turn black, and develop a greasy appearance. Bacterial Spot cannot be cured. The first line of defense, if the disease is identified early in its development, is to apply a copper-based fungicide every 7 to 10 days until 3 to 4 weeks before harvest. Prune the infected parts immediately, disinfecting tools and hands in a bleach solution after each cut. If good results don’t show up after a second spraying of fungicide, the plant or tree must be destroyed. Try to prevent bacterial spot by following good fall cleanup practices.

Fusarium Wilt – Yellowing of the leaves occurs in tomatoes infected with fusarium wilt. This yellowing spreads upward from the base of the plant as the disease progresses. It may occur on only one side of a leaf midrib or on one side of a plant. The leaves wilt noticeably before they die, and the whole plant eventually dies. In most cases you should remove and destroy infected plants. Fungicides are not effective against fusarium fungi.

I hope this was helpful. Please feel free to contact us again if you have further questions.