Growing Tomatoes – Common Diseases and Pest Information

Fresh tomatoes are both delicious and nutritious, and growing your own tomatoes in your garden can be a wonderful and rewarding experience. One of the great things about tomatoes is that even beginner gardeners can grow them, but it is important for those gardeners to be on the lookout for common diseases, insect infestations and other problems. Tomato plants can be prone to a number of diseases and conditions and it is important for tomato growers to watch for the early warning signs.

The good news for gardeners is that the diseases contracted by tomato plants are rarely fatal to the plants. If gardeners pay attention to the early warning signs and treat the problems promptly, the plants should be able to recover promptly and grow some delicious tomatoes.

Early Blight

Gardeners should watch their tomato plants for signs of early blight . This common disease will be most evident on the foliage of the plants, but it can often be seen on the stems and even on the fruit itself.

The classic symptom of early blight is dark spots surrounded by concentric rings. These rings will typically develop on the older leaves first, and then they will start to invade the younger foliage, stems and fruit. The affected foliage areas will often turn yellow, and they may die prematurely as well.

Early blight is a soil based problem and the fungus that causes it can survive the winter. In order to control the problem gardeners should remote the affected plants and clean the garden thoroughly. Copper and sulfur sprays can be effective at reducing the spread of the disease, as can proper management of the garden.

Late Blight

Like early blight, late blight can affect both the leaves and the fruits of tomato plants. Late blight, however, spreads much more rapidly than early blight , so it is important for gardeners to be on the lookout for signs of the disease. Cool and wet weather conditions can make encourage the growth of late blight, so if those weather conditions are present it is important for gardeners to be especially vigilant.

Common signs of late blight include greasy looking spots on the leaves, often gray in color, as well as rings of white mold around those spots. These spots will eventually dry out and develop a papery appearance. Gardeners may also notice black areas on the stems, while the fruit may harbor greasy gray spots as well. The key to controlling this serious disease is to treat it promptly. Sulfur can be effective if the disease is caught early.

Gray Leaf Spot

This common tomato disease gets its name from the distinctive gray spots that form on the affected plants. As with blight, the fist signs of infection are seen on the oldest leaves, but the illness can quickly spread to the other leaves as well. The spots on the leaves will enlarge and eventually turn a grayish brown color. As the disease spreads the center of the spots will crack and fall off, while the surrounding leaves will turn yellow and begin to drop. This disease will also inhibit tomato production, so it is important for gardeners to treat it as soon as possible.

The first thing gardeners should do to reduce a problem with gray spot disease is to manage their gardens properly. Moist and warm conditions will make gray spot disease worse, so it is important not to over-water the plants. As soon as the disease has been identified it is important to remove all affected plants and garden debris at once. It is also a good idea to use tomato varieties that have been engineered to be resistant to this common problem.

Septoria Leaf Spot

The first sign of Septoria Leaf Spot, a common disease, is the appearance of papery patches on the leaves . Over time these patches will develop small black spots inside them. The older leaves will be affected by leaf spot first, but the disease can quickly spread to the younger foliage as well.

Copper sprays can be effective against this problem, but it is important for gardeners to begin their treatment regimens as soon as possible. Early treatment is the best defense against this common problem.

Verticillium Wilt

The first signs of verticillium wilt are often yellow leaves that have a dry and turned up appearance. If gardeners notice these symptoms they should act at once, since this disease is caused by a fungus that lives in the soil. This same fungus can affect many different vegetables, so the problem can easily spread throughout the entire garden. Other symptoms to look out for include wilting, especially during the heat of the day, and yellowing or browning between the veins of the leaves, beginning with the oldest leaves.

The fungus that causes verticillium wilt will eventually interfere with the ability of the plants to take in water, and that can be fatal. In order to control the problem gardeners should remove the affected plants along with any garden debris. It is important to remove any infected plants right away, since the disease can quickly spread throughout the garden and affect other varieties of vegetables as well.

Tomato plants are also prone to a number of garden pests, and it is important for gardeners to be on the lookout for the early warning signs. Some of the most common garden pests tomato growers should watch out for include the following.


Aphids are tiny insects , generally either green or black, and they tend to cluster on the underside of the leaves of the tomato plants. The first sign of an aphid problem is often the appearance of curled and distorted leaves. Gardeners may also notice that their plants are not growing as quickly as they should.

For a localized problem gardeners can blast the insects off of the plants with water, or the aphids can be picked off by hand. An application of special insecticidal soap can also be effective against aphids.

Blister Beetles

Gardeners will also need to be on the lookout for blister beetles, slender black, gray or striped insects. These bugs are easier to see than aphids, since they are generally at least half an inch long. Gardeners can use pyrethrins to control them, or they can be picked off by hand. When picking these bugs off of the plants gardeners should be sure to wear gloves, since the beetles can let off a caustic fluid when they are frightened or disturbed.

Stink Bugs

There are several varieties of stink bugs that inhabit tomato plants, so gardeners should be on the lookout for black, grown or green bugs with no markings and a distinctive shield shape. Controlling the growth of weeds around the tomato plants can reduce the appearance of these troublesome creatures, and a dust of sabadilla can be used to treat an infestation.

Tomato Hornworm

Tomato hornworms appear as ¾” long caterpillars, green in color with diagonal lines on their sides and a prominent horn on the rear end. If left untreated these caterpillars will quickly eat through the tomato plants and destroy it, but the good news is that these large caterpillars are easy to spot and easy to remove by hand.

Being on the lookout for these common problems is one of the best ways to keep your garden pest free and ensure you will be enjoying fresh and delicious tomatoes all summer long. By remaining vigilant gardeners can ensure that their tomato plants stay protected and keep producing those large, juicy and wonderful fruits.

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