Welcome to the wonderful world of tomato plant diseases. This short list of 20 popular tomato plant diseases and their treatments will help you identify a problem early, so that you can fix it and save your tomato gardens and bring them back to grow and produce sweet, delicious tomatoes next season. The good news is, most of these problems are easily corrected and easily preventable with early detection and appropriate treatment.
Weeding Tomatoes: Weeds can be bad business for your tomato crops. They’re a lot slower growing than fruit plants, but they also take more water, thus decreasing your nitrogen and phosphorous figures in your soil. Most weeds are tolerant to a light frost. You can control the weed population by pre-weeding, timing the weeding carefully, and using an herbicide. You should also lightly water the soil after weeding, to give it a chance to drain excess water from the soil, before your next application of fertilizer.
Leaf Spot and Mildew: These diseases occur when too much water is taken out of the soil, causing a loss of moisture in the soil for the plants. Most often, they are set in place by other pests or disease, and you might not even know about them unless you are doing a thorough gardening inspection of your garden. To detect leaf spots, dig up a handful of healthy leaves and squeeze them dry. If the spots are black, they are probably leaf spots. For mildew, you can apply a commercial prevention product like Rust Control to the area.
Rotting of Tomatoes And Other Tomatoes: Most tomato plant diseases are caused by fungi. Most of the time, fungi will infect a plant that has not been weeded properly, like young seedlings that have not yet been planted in the garden. You can identify rot diseases easily by looking at the foliage and discoloring of the plant and by carefully watching for brown, smoky spots on the plants.
Aphids: These nematodes damage the foliage of plants by feeding on the sap or juices. They cause a powdery, sticky destruction of the plant foliage. Aphids are particularly active during the warmer months, when they are attracted to plants that are receiving heavy watering. In winter, they feed on fruits that are still on the tree or bush. The nematode may survive for some time until spring, when it searches for warmer areas to feed.
Whiteflies: These are a type of pest called caddisflies, which live and lay their eggs on plant surfaces. They usually cause mild infestations, especially in containers. Whiteflies are attracted to plant leaves, stems, and fruits, but can also be found on soil, rocks, and drains. Some resistant varieties can remain alive under cold conditions.
Scales: These are small insects with smooth bodies and dark brown or blackish color on the lower surface of their body. They have long narrow bodies, and short antennae which guide them to food. They damage roots and can even be found under plant leaves, stems, and fruits. They feed on the sap of tomatoes, raisins, and cantaloupe.
Brown Canker: This species occurs on the underside of leaf blades and can damage the inner bark and foliage of plants. It can be confused with scale insects on the plant leaves, stems, and fruits. It is more difficult to spread disease to tomato plants than other insects. It is a common problem with citrus groves, especially the young shoots growing close together.
Black Spots: These are also small pests that can damage roots and leaves. They usually appear as dark spots on a plant leaf, trunk, or fruit. They have wide mouth parts and are attracted to the chemical composition of the tomato plants and soil. They can survive in poor soil conditions, but are not as good on organic matter or compost as some of the other environmental conditions mentioned above.
The main diseases that are treated with systemic pesticides, like the systemic fungicides mentioned above, are diplobacteriosis, aeruginosa, and mycotoxins. These are diseases that develop in the soil, which is rich in nutrients. They tend to affect plants in warm climates and in soil that are not chemically treated. They need specific conditions, such as high nitrate and phosphorous content soil, to flourish.
Watering Wounds: In extreme cases, aphids can cause plants to die when they suck out plant juices. This may cause leaves to become curled and turn black. Aphid growth can cause the plant leaves to curl up, which can eventually break off from the plant. The leaves will eventually fall from the plant and then grow in new shoots. If the leaves die off, the plant dies off too. Aphids only attack healthy plants, so it is unlikely they will harm tomato plants unless they are excessively fed.