Diseases

How to Fix Problems and Diseases Endemic to Tomato Plants

Why do we get the most questions asked about problems with tomato plants?

I think it’s because millions of gardeners are planning to grow their own healthy food every year. Of all the veggies raised, the most common seems to be concerns about growing tomato plants.

It’s easy to understand why this is true. Homegrown tomatoes are always 100% tastier than those bought at the grocery store.

It should come as no surprise that most gardeners include tomatoes in their garden, growing them in containers, hanging baskets and other innovative, growing pursuits.

Unfortunately, many obstacles stand in the way of successful tomato growing. In this article, we will discuss the top twenty-one challenges tomato growers will be most likely to encounter. Read on to learn more.

Challenges And Tomato Growing Problems

The cycle of growing tomatoes is usually followed by dissatisfaction. Though easy to grow, these plants seem to tend to come up with all sorts of complications.

For example, some plants don’t set fruit. Some set fruit but is plagued by black, spongy spots on the bottom. In a more dramatic development, your plants may look perfect one day and collapsed or stripped of all leaves and fruit the next.

These are just a few of the many issues that plague aspiring tomato growers. Fortunately it’s pretty easy to deal with these and many other irritating tomato problems. Start by becoming familiar with the common threats to tomatoes.

Learn To Recognize Multiple Tomato Plant Diseases, Pests & Other Problems

The first step in the treatment of any ailing plant is correct identification of the problem. Follow these three steps to learn exactly what happens to your plant:

Identify The Affected Part Of The Plant

Is it the:

  • Roots
  • Stems
  • Leaves
  • Blossoms
  • Fruit
  • All of the above

Compare and Contrast

What do you notice when you compare your ailing plant to a healthy one?

Take note! Healthy tomato plants display soft, fuzzy leaves in a shade of medium-to-dark green.

If the leaves of your tomato plants are brown, yellowed, and have dark patches or ragged holes or margins, this is a sign of trouble.

Be also on the lookout for spots on tomato leaves that develop dirty, rusty mold or mildew.

Are Your Plants Buggy?

Examine your plants for insects. Some insects are beneficial, and some are detrimental. Check with your local Cooperative Extension Service if you need help identifying the bugs you find.

The appearance of some beneficial insects may suggest some harmful insects may be present.

For instance ladybugs on your plants may mean aphids or other tiny bugs are present.

You don’t want to kill the good ladybugs, because they’re working hard to swallow up and kill sap-sucking aphids.

Following these three simple steps will help you determine the cause of the problem.

The Most Common Tomato Plant Problems

There are approximately sixteen ailments that plague tomato plants.

These are variously caused by:

  • Inadequate or flawed care
  • Bacteria
  • Fungus

7 Common Growing Conditions Found To Reduce Tomato Plant Quality and Harvest

Tomato plants can be severely damaged or destroyed by disease, fungi and/or poor growing practices. Sometimes you can treat and save a plant, but very often it’s better to destroy the plant to avoid spreading the disease to your other plants.

In all cases, prevention is smarter than intervention. The best offense is to provide the ideal growing conditions to prevent the onset of fungal diseases and infection in the first place.

Pay close attention to avoid the below conditions in your tomato patch:

Lacking Fertilizer:

Provide enough organic matter in the soil and carefully add commercial fertilizer throughout the life of the plants according to packaging directions.

Excessive Pruning:

Tomato plants use their leaves for photosynthesis and to preserve the tomato fruit from harsh conditions. Learn how to prune tomatoes. Hold a tomato cage in place to support the plant and carry leaves and fruit weight.

Calcium Deficiency:

Test your soil regularly. Maintain a pH level of about 6.5 and apply gypsum and lime to boost calcium levels and promote healthy growth. More on:

  • Tomatoes and blossom-end rot
  • Calcium deficiency in tomato plants

Early Planting:

Tomatoes planted too early; they will not thrive. Check with your local extension or almanac to determine the right time for planting in your hardiness zone.

Poor Watering Habits:

Too much water promotes root rot. Too little water promotes hard, dry fruit. Provide even watering (approximately 2″ a week) throughout your growing season. Soaker hoses are great for watering tomatoes.

Overhead Watering:

Try not to get wet leaves on your crop. Fuzzy leaves of tomatoes tend to dry gradually, and this can promote fungal growth. Also over-water your plants with a soaker hose or simply allowing water to saturate the ground at a drip at the base of your plants.

Poor Air Circulation:

Lack of air circulation between and through your plants can also cause fungal growth. Be sure to plant tomatoes far enough apart to allow for free growth and good air movement. If you see powdery mildew growth, apply a fungicide right away.

16 Common Tomato Plant DIsease or Ailments To Watch Out For

Blossom End Rot

Blossom end rot manifests as a black spot on the bottom of an otherwise plump, healthy tomato. Even if you cut off this bad spot, you will find the flesh of the fruit is mealy and unappetizing.

Poor watering habits or hot, dry weather may cause or worsen problems with blossom-end rot. It may also happen when plants do not get the right amount of calcium.

Two reasons why this may happen. There is just not enough calcium in the garden soil, or the soil pH level is low preventing the plant from being able to absorb the available calcium present. The pH level of your soil should be about 6.5 for good tomato growth.

Test the soil before planting in the spring, to avoid the problem. In your local nursery, you can find a soil test kit, or call your Cooperative Extension for support. If you’ve had blossom end rot trouble before, make sure to share the detail with them.

Ask for advice, and follow it carefully. Don’t just add gypsum or lime willy-nilly to your soil and expect your calcium problems to disappear. It’s important to first test the soil, pinpoint the problem and take appropriate steps to remedy it.

Make sure to add broken eggshells to your compost pile if you are using organic, homemade compost in your yard. That is a good natural source of calcium.

Later in the growing season, you may wish to mix up a foliar spray containing calcium chloride. Spray this on your plants in the morning so it will have all day to dry in place.

Don’t spray it when the sun is very bright as this may cause the leaves to become burned. When you do foliar spraying provide a ground watering simultaneously. This application can help prevent blossom end rot on existing fruit.

Blossom Drop

Blossom Drop occurs when plants produce flowers that drop off before developing into fruit.

This tends to happen at dramatically fluctuating outdoor temperatures. At temperatures ranging from 55F-75F the tomatoes are happiest. Too little water, too little or too much nitrogen, insect damage or lack of pollinating insects (or lack of manual pollination) are other reasons for this phenomenon.

To prevent these problems, start with healthy plants. Select a setting that gets ample sun, has good drainage and is somewhat sheltered from punishing winds. If a cold snap is predicted, cover the plants. During scorching weather provide shade.

Attract pollinating insects to your garden (e.g., butterflies, bees, ladybugs, and others) by planting flowers and native plants such as easy to grow cosmos, milkweed, and other “pollinator garden” choices.

Avoid using chemical pesticides as these will kill off the beneficial insects and may not deliver the desired effect on the detrimental insects. Judicious application of a neem oil based product is preferable.

Fruit Cracks

Fruit cracks usually appear as concentric circles allowing opportunistic birds and insects to feast on the developing fruit.

Poor watering habits coupled with heavy rain following a period of drought cause the cracking of the fruit.

If your tomato plants are thirsty and a heavy rainfall occurs during hot weather, the plants will take up water very quickly. This causes the fruit to swell rapidly, and the skin will crack naturally. Avoid this problem by keeping your plants properly watered at all phases of growth.

Sunscald

Sunscald affects healthy plants with plump, ripe fruit. Exposure to the excessively hot, punishing rays of the sun, allows the fruit to scald, creating paper-thin yellow and white spots on tomato leaves and skin. This affects both the appearance and the flavor of the fruit.

To avoid the problem, be careful not to prune plants excessively. Remember the leaves serve to protect the fruit from excess sun. In very hot, dry areas you may want to use a shade cloth during the hottest part of the day to protect plants from very harsh sunlight.

Poor Fruit Set

Poor Fruit Set occurs when plants produce some flowers and very few small, flavorless tomatoes. The cause? High levels of nitrogen in the soil. Nitrogen nourishes leaf growth, but it does not nourish fruit development.

Plant crowding can cause that problem as well. If plants lack sufficient space they may not be able to pollinate efficiently. Tomato blossoms contain parts of both the female and the male so they pollinate themselves; nonetheless, for pollination to occur they require good air circulation.

Overcrowded plants impair air movement. Avoid the problem by testing the soil before planting and rectify any imbalances. Space plants correctly (about two feet apart) to allow plenty of room for growth and good circulation of the air.

To ensure good pollination, gently shake the branches of your plants when in flower and the petals of the blossoms are curled back. The window of opportunity for manual pollination is about three days. Keep a close eye on your plants to give them a good shaking at the right time.

Cat Facing

Cat Facing is a term used to describe lumpy, bumpy and rippled tomatoes.

The reason for the problem is unclear, but it appears that disturbing the flowers or buds (e.g., sudden temperature drops) may be one cause. Damage from exposure to herbicides may be another.

Try seeding tomatoes later in the season when the weather is a little warmer to prevent the problem. You can also use an instrument known as the “Wall of Water.” This is a series of water-filled plastic tubes which are arranged in a manner that covers the tomato plant. The temperature of the water keeps the plants moist through the night.

Another way to avoid chilling the blossoms and buds and preventing weed growth is by using black plastic mulch to cover the ground and the area around the plants. During daylight hours, the plastic absorbs heat, and radiates it overnight. Just be careful not to leave the plastic in place after the weather becomes very dry, because it could lift dangerously high temperatures.

Leaf Roll

Leaf Roll is a phenomenon which happens to mature plants. You will notice that the plants’ leaves begin rolling up from the outer edges toward the center.

This condition may strike most of the plant’s leaves, but it is not dangerous and won’t negatively impact fruit development.

Excessive pruning, excessively wet or dry soil and very high temperatures may cause leaf roll.

To avoid the problem, avoid overpruning and provide a light, well-draining soil for the plants. Watch the water and moisture in the soil properly. Don’t allow your plants to suffer from drought for long periods of time or stand in water.

Puffiness

Puffiness goes unnoticed until you slice into your tomato. Plants grow, bloom, set and develop fruit just fine, but the inside of the tomatoes remains hollow. The only clue you might have is that tomatoes will feel light when you pick them. They may also be somewhat cube-shaped instead of being round.

This problem is caused by poor soil and/or lack of fertilizer, too much nitrogen in the soil or too much rain. Inadequate pollination may also be the cause.

To prevent puffiness, amend your soil with plenty of organic compost and use a balanced fertilizer (10-10-10) once or twice a month. Top-dress the soil regularly with organic matter and feed compost tea. Remember that tomatoes need lots of nourishment to produce good fruit.

Bacterial Canker

Bacterial Canker manifests as creamy white spots on nearly ripe tomatoes. If you see a dark rim around the bacterial spots, you will know that you are dealing with bacterial canker. [source]

This tomato disease is caused by a naturally occurring bacteria known as Clavibacter michiganensis. It is most often introduced to a garden setting by tools that have been exposed to the pathogen or by plants. Shared tomato seeds may also be contaminated.

When the bacteria invades the garden soil, it spreads by rainwater or sprayed water splashing from the ground onto plant leaves and stems.

Recently pruned plants, or plants with a broken branch or insect damage, offer opportunities for the bacteria to enter the plant. For this reason, do not work in your garden immediately after a rain shower or prune your plants when they are wet.

To prevent contamination and bacterial wilt:

  • Clean garden tools thoroughly with hot water and bleach after each use. [source]
  • Keep new plants separate from your garden area for a week or two before transplanting them.
  • Rotate crops regularly to prevent all bacteria and tomato plant diseases from being able to get a foothold.
  • If you have contaminated plants, put them into sealed plastic bags for trash pickup. Don’t compost them.

Anthracnose

Symptoms of anthracnose look like blossom end rot, but instead of a solid black spot on tomatoes at the bottom of a ripe tomato, you’ll see a circle shaped with bulls-eyes. That spot will be mushy and sunken, and you’ll find mushy black rot when you slice open the tomato.

The fungus disease which causes anthracnose is Colletotrichum phomoides which thrives in hot, humid weather. Using sprinklers or overhead irrigation methods facilitates the spread of this fungus as they cause it to splash up out of the soil and onto the plants.

To avoid Anthracnose diseases remember to groundwater your plants. Harvest your tomatoes promptly, allowing them to stay on the vine, gives the fungus more opportunity to infest them.

Early Blight

Early Blight shows up as brown spots on tomatoes leaves. The brown spots spread into rings for a target-like appearance. Foliage fades on infected plants from green to yellow in the areas surrounding the spots. Eventually, the leaves turn brown, die and fall. In the end, your plants may be bare.

This disease is caused by the fungus known as Alternaria solani which can over-winter in the garden soil. If you have this problem one growing season, you will need to take steps to deal with it before planting again. Learn more about Alternaria leaf spot.

Make a habit of rotating your crops from one season to the next as this (and other fungi and bacteria) do not thrive on all plants. Changing your plantings from year-to-year will prevent having the fungus take hold. Be advised, early blight also thrives on peppers, eggplant and tomatoes, so don’t rotate these types of veggies in the same spot.

Tomatoes with Late Blight

Tomato fruit with “Late Blight”

Late blight is another “blight” tomato battles caused by phytophthora infestans. Learn about preventing and treating Late Blight.

Septoria Leaf Spot

Septoria Leaf Spot covers the underside of infected young plants. You will note the yellow spots appear in the lower foliage that soon form dark borders and gray centers. Shortly after that, in the middle of the blemish, a black dot appears, and the leaf then dies and falls.

This fungus is called Septoria lycopersici which causes the problem. As with most other fungal and bacterial infections, by avoiding top watering of your plants, you can reduce the risk of it developing and spreading.A good fungicide like Certis Double Nickel 55™ which targets Septoria Leaf spot will help if the problem does grow.

Fusarium Wilt

Fusarium Wilt causes the tomatoes and many other plants to suddenly wilting. One day the tomato plants will look fine, and the next mostly or fully wilted. Watering just exacerbates the problem and the contaminated plant will be dead within a few days.

A pernicious fungus known as Fusarium oxysporum f.sp. lycopersici is the problem.

The fungus resides in the soil and attacks plants’ vascular systems. It does this by destroying the xylem tubes. These are the vessels which move water and nutrients through the stems and into the leaves.

To avoid letting Fusarium take hold, be sure to rotate your crops yearly. Wilt-resistant tomato varieties have the best chance of fighting off the fungus.

Verticillium Wilt

Verticillium Wilt is another fungal infection that manifests as yellow spots on the bottom leaves of the plant. You may also see V-shaped lesions on leaf edges. [source]

Blotches spread rapidly and cause leaf veins to become brown. Soon foliage becomes brown altogether, die and fall. At this point, the disease attacks the stem and stunts plant growth.

Verticillium albo-atrum is very much like Fusarium. It dwells in the soil and is taken up by the plant with water. Rather than destroying the xylem tubes, it blocks them and prevents water from traveling normally through the plant.

As with all fungus, crop rotation can help protect your plants. Wilt-resistant varieties are somewhat able to defend themselves against Verticillium infection.

Viral Tomato Diseases

Viral Disease cause black stripes and/or spots on tomatoes. Of course, some heirloom tomatoes have natural spots and stripes. However, if you see this type of marking suddenly appear on a standard red tomato, it is cause for concern.

Viruses are always present but are more likely to spread and thrive when plants are under stress. For this reason, your plants are more susceptible during drought conditions or when poorly cared for.

A plant growing in good soil and receiving the right amount of food and water is less likely to succumb to a virus than one “growing” in neglect.

To prevent viral infection, take good care of your tomato plants. If you fear your plant has already contracted a virus, treat it with a neem oil spray and give it some TLC.

NOTE: If you smoke always wash your hands before handling or working with your plants because of the potential infection of the tobacco mosaic virus.

Powdery Mildew

powdery mildew on tomato leaves

Close up of Powdery Mildew on Tomato Foliage

Powdery Mildew is another fungus that appears as a white powder covering the leaves and stems of your tomato plant. If ignored, it will cause the plant’s foliage to yellow and then become brown. Finally, they will fall.

This fungus is caused by a combination of high humidity and low airflow. You are more likely to see it in greenhouse plants than in garden plants. To prevent developing powdery mildew, give your plants plenty of space to grow, prune judiciously and don’t use overhead watering methods.

If you do find powdery mildew on your plants, use a foliar sulfur spray.

6 Solutions For Dealing With Tomato Plant Pests

Detrimental insects can do a great deal of damage to your plants, but it is important to learn how to differentiate between the bad bugs and the good bugs.

There are plenty of beneficial insects that can do a lot to help you keep control of your bug rivals. Nonetheless, when there is a large population of beneficial insects, a well-balanced garden overflowing with healthy plants will have little to fear from harmful insects.

In addition to natural predators, here are 6 good solutions for dealing with harmful insects on your tomato plants:

Bacillus thuringiensis

Bacillus thuringiensis is a natural bacteria that kills caterpillars.

It is effective against tomato hornworms, tomato loving beet army worms, and other caterpillar pests; however, it will also kill butterfly caterpillars, so take care to recognize your caterpillars before applying this solution.

Establish a butterfly/pollinator garden to attract beneficial insects and relocate any butterfly caterpillars that might stray into your veggie garden.

More on Caterpillar Control with How To Keep Caterpillars Off Plants

Homemade Insect Killing Or Repelling Sprays

There are many non-toxic spray recipes, which kill or repel unwanted insects. Using these organic items means you don’t feed your family’s pesticide-filled food. Alternatively, all-natural, organic sprays of insects can save you massive piles of money.

Insecticidal soaps

These pest killing insecticidal soaps are generally safe to use throughout the growth cycle of your plant.

These are particularly effective against tiny insect pests, like spider mites, mealybugs and aphids; Ladybugs, however, are also quite effective against those tiny invaders.

Insecticidal Soap Containing Pyrethrin

This soap is effective against tiny pests and also larger bugs such as tomato hornworms and potato beetles.

However, big bugs can also be effectively dealt with by simply picking them off and dropping them into a bucket of soapy water on a regular basis.

Neem oil

Neem oil insecticide sprays for plants is a very safe and effective natural pesticide product that kills all manner of insects at all stages of life.

Regular spraying with a mild solution of natural neem oil and water helps keep your plant’s pest free.

Insect traps

Insect Traps can work to distract pests from your plants and trap them to prevent them from ever having the chance to do damage.

Do not use any kind of glue traps as they are infamous for capturing accidental targets like butterflies, bees, colibris and other beneficial garden dwellers.

5 Detrimental Pests That Will Decimate Your Tomato Plants

Cutworms

Cutworms are not really worms. They are moth larvae, and like moths, they are active after dark. They come in the night to chop down tomato plant seedlings. They do this by eating through the stems just above the soil level.

To prevent this, you can outfit each seedling with a cardboard collar that encircles the entire stem. Paper towel or toilet paper cylinders cut into rings a little over an inch wide are perfect for this.

Place the ring above the plant and press it a little bit into the soil to block access to cut worms. When multiple sets of leaves have grown in your plant, you can either remove the collar, or just leave it to decompose.

Tomato Hornworms

Tomato caterpillars are also called “Tobacco Worms.” These caterpillars are very big (2″-4″long) but they are hard to see because they are the same color and width as the stems and branches of a tomato plant.

These caterpillars are very aggressive and can overnight eat a whole, fully grown tomato plant. They work very methodically, swallowing all the leaves in their way and going on in their wake leaving a swath of barren trees.

Plants can be treated with B.t. Later on, you should kill hornworms when they appear and/or lure parasitic wasps to your garden to treat them. Beneficial wasps lay the hornworms on their nests. When the eggs hatch the caterpillar is killed by the wasp larvae.

Tomato hornworm with eggs of beneficial wasp

Companion planting is also a good way to deal with hornworms. Try planting marigolds amongst your tomato plants as they naturally repel hornworms.

Colorado Potato Beetles

The Colorado Potato beetle eats all members of the family of night shades (potatoes, tomatoes, and aubergines). Such sporty-looking dime-sized devils are stripped orange / yellow and black and suck with amazing pace night shadow buds.

Their larvae are also voracious and eat entire plants, stems and all.

The larvae are red or pink with black spots. You may see them hiding on the undersides of the leaves during the daytime. You can also find yellow or gold clusters of Potato Beetle eggs on the undersides of leaves.

Pyrethrin spray and neem spray are both effective against the larvae and the adults. You can also shake the adults and larvae off the plants into a bucket of soapy water.

Examine the undersides of leaves and clip off any leaves with egg clusters. Put these leaves into a sealed plastic bag and dispose of plant debris in the trash.

TIP: Be careful not to mistake clusters of beneficial ladybug eggs for detrimental potato beetle eggs!

Brown Marmorated Stink Bugs

The Brown Marmorated Stink Bugs are problematic in the home and in the garden. These large, bizarre looking bugs have straw-like mouth parts which they use to suck liquids out of fruits.

You will see yellow blemishes on the surface of maturing tomatoes as they damage the tomatoes, and irregular areas. The areas which have been damaged by stink bugs are white when you slice a damaged tomato open.

These bugs seem to be resistant to most pesticides.

To deal with stink bugs, you can purchase specially made traps from Safer® Brand. You should also take steps to prevent them from getting a foothold.

Because the bugs like to hide out and breed in homes and outbuildings, be sure to seal cracks and crevices.

Choose the bugs as you see them on tomato plants and drop them into soapy water, but wear plastic, disposable gloves to do so and be careful not to inhale their scent. The skin and nasal passages may get irritated by contact with them.

Spider Mites

Spider Mites are very small, but they do a lot of damage. They congregate on the leaves and stems of plants and suck the juices out leaving patchy, brown scars behind.

Neem oil spray and insecticidal soap also help to get rid of the spider mites. They will also get short work from a stable ladybug community.

Birds, Terrapins & Some Lizards Like To Eat Tomatoes

Tomatoes are tasty and all manner of wildlife will enjoy them if they can get to them. Birds will land on the plants and peck at the fruit.

If you’re lucky enough to have terrapins in your yard, they could take a couple of bites of low-hanging fruit. If you live in a tropical area with large, lizards eating veggies, they will be happy to eat your tomatoes. Deer and chipmunks like tomatoes too.

Physical barriers will keep critters out of your tomatoes. A low wall will prevent terrapins from getting in, a tall fence will keep deer out.

Sturdy netting can keep birds, large lizards, and small mammals out, but be sure it is strung tightly on sturdy poles. Loose netting presents an entanglement hazard to birds, lizards, and small mammals. They can get caught and break legs and wings.

Setting up a wildlife-friendly garden is also a good way to deal with hungry wildlife.

Many people just let some sort of wild veggie garden spring up in a remote location from extra seedlings and castoff plants. A good setting is near a compost heap. Also ideal for your pollinator garden, this sort of out – of-the-way setting.

Don’t Be Afraid! Tomatoes Are Easy To Grow!

After reading this long list of tomato issues, you might feel a little daunted at the prospect of trying to grow them. Don’t be.

The bottom line when growing tomatoes or any garden plant is that healthy plants that are well cared for tend to deflect disease and pests, so if you take good care of your plants, your battle is half won.

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