Are tomato leaves edible in abundance?

Myth #1: Nightshades are highly poisonous

When referring to the Solanaceae family of plants, many people call it by its more common moniker, the nightshade family.

Within this family are the vegetables we know and love, like tomatoes, tomatillos, potatoes, eggplants, and sweet and hot peppers.

But also within this family are the nightshades famously known to be toxic to humans, like black henbane, mandrake, and the “deadly nightshade,” also known as belladonna (Atropa belladonna).

Despite its nickname, belladonna, an herbaceous perennial, has historical use in herbal medicine as a pain reliever and muscle relaxer, a treatment for stomach and intestinal issues, and even as a beauty aid.

In fact, the name “bella donna” means beautiful lady in Italian. It comes from the outdated practice of women putting drops of belladonna berry juice in their eyes to dilate their pupils. The look was considered attractive in the day!

But rest assured that though tomatoes are distantly related to belladonna, they do not contain the chemical compounds that make belladonna (especially its berries) so poisonous.

The tomato (Solanum lycopersicum) does have an interesting history however, as its scientific name, lycopersicum, is Latin for “wolf peach” and derives from German folklore.

When the tomato was brought to Europe in the 16th century, people believed it to be poisonous like other members of the Solanaceae family. Legend had it that witches used these hallucinogenic plants in potions to conjure werewolves. Since the tomato plant’s fruit looked so similar to that of belladonna, it was dubbed the wolf peach.

You see, tomatoes of yore looked nothing like the plump, juicy, fashionable tomatoes we know and love. Before modern cultivation, tomatoes grew wild in the Andes and they were tiny—the size of a blueberry. Their shape and color were often mistaken for belladonna berries.

Wild tomatoes on a vine. Image: Aris Gionis.
Wild tomatoes on a vine. Image: Aris Gionis.

These days, we know that while tomatoes belong to the (very large and diverse) nightshade family, they definitely aren’t of the deadly nightshade variety.

This ambivalence was later reflected in the tomato’s other accepted scientific name, Lycopersicon esculentum (translated to “edible wolf peach”).

As you can see, the bad rap bestowed on tomatoes is simply an old wives’ tale, left over from a less-informed era.

Video

How to Fertilize After Your Tomatoes Set Fruit

You’re harvesting tomatoes; you made it! You

You’re harvesting tomatoes; you made it! You’ve successfully provided your tomatoes with the correct nutrients at the correct time.

Once tomatoes begin setting fruit, you can usually switch to a balanced NPK fertilizer or continue with one that is lower in nitrogen than phosphorous and potassium.

Keep an eye on your plants and look for signs of a nutrient deficiency

Dr. Earth Premium Gold All Purpose Fertilizer

Purely Organic Products Tomato & Vegetable Plant Food

  • Pale yellow-white leaves are a sign of nitrogen deficiency.
  • Phosphorous deficient tomato plants usually have a stunted look to them, can have purplish stems, and may develop spots on the leaves.
  • Potassium deficient tomato leaves have a stained-glass look, with the veins remaining green and the rest of the leaf turning yellow. The tips of the leaves may also turn brown.

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5. Potential Benefits of Eating Tomato Leaves

Now that we’ve covered the relative safety of cons

Now that we’ve covered the relative safety of consuming tomato leaves, let’s see the potential benefits from this food source. After all, they’re green and might have many nutrients that can benefit our body instead of harming it. 

According to at least one study, we know that tomato leaves and stems have a higher concentration of antioxidants than the rest of the plant. These parts also contain more polyphenols, while are plant-based micronutrients. When taken together, these substances can help our bodies fight off diseases and enjoy improved health in general. 

One very surprising concept that’s come to light is that tomatine might actually be a kind of cancer inhibitor. This is because the glycoalkaloid is known to suppress or even kill cancer cells within the stomach, colon, liver, and breasts. 

The study that shows these findings also suggests that we should eat more items that are high in tomatine, such as tomato leaves and green tomatoes. There might also be a future need to cultivate red tomatoes that have high levels of tomatine in order to treat cancer. 

Fertilizing Established Tomato Plants or Nursery Starters

Perhaps you’ve skipped starting your tomatoe

Perhaps you’ve skipped starting your tomatoes from seed and purchased plants at the nursery. Or your seedlings are potted up now and well-established in their pots. In either case, your tomato’s feeding needs change a bit.

You’ll still want to continue to use a balanced NPK fertilizer or something with a little more phosphorus. However, at this stage, once the plant is around six inches tall and well established, you can switch to feeding full strength.

Continue feeding your plants once a week.

Leaf problems due to tomato plant diseases

Tobacco Mosaic Virus

Dappled yellow leaves with twisty new growth are common with tobacco mosaic virus. This virus is often transmitted by insects and especially aphids.

Do not try to treat these plants. Destroy them and remove them from your property, and be sure to wash your hands after touching any plant you suspect could be infected with this virus.

When choosing tomato varieties for future gardening seasons, look for the TMV resistant label.

Bacterial Speck and Bacterial Leaf Spot

Small dark spots on leaves that then turn brown and fall off are a symptom of bacterial speck and bacterial leaf spot. These diseases thrive in hot, humid environments and can be transmitted by your hands and garden tools.

Be careful working with plants suspected to be infected with this disease. To prevent future issues, remove and destroy severely infected plants and choose varieties with BLS and PST resistance in the future.

Late Blight on tomatoes

Leaves develop brown patches that turn dry and papery when they become infected with late blight. Sometimes a white mold grows along the edges of the brown patches. If your tomato plants have late blight you will also notice blackened areas along the stems and the tomatoes develop hard brown lesions.

Late blight on a tomato plant.

Late blight on a tomato plant.

Late blight will wipe out your tomato crop, and there is no treatment for infected plants. So try to prevent this disease by removing and destroying infected plants. Don’t compost them. Send them to the landfill and clean and remove all remnants of the infected crops from your garden.

Here’s a video from the University of Maine about late blight:

For future crops, try applying a preventative copper fungicide or Bacillus subtilis spray, make sure to water your plants at the base as wet conditions favor the spread of this disease, and look for resistant varieties labeled LB.

Septoria Leaf Spot

Septoria leaf spot has a similar appearance, but the brown patches are circular with light centers and dark specks. And the disease will start with the older leaves. Trim off infected leaves and remove them from your garden. Sanitize your hands after dealing with infected plants.

Early Blight on tomato plants

Early blight causes spots of dark concentric rings on leaves and stem of the lower plant first.

Early blight tends to strike your tomato plants when they’re loaded with fruit and days are humid and warm.

Preventative sprays may help slow the onset and spread of the disease, but infected plants should be removed and destroyed. Look for resistant varieties labeled AB (A for Alternaria fungal species) for future gardens.

Tomato Spotted Wilt Virus

Tomato Spotted Wilt Virus

Dark brown rings on the leaves can also be caused by tomato spotted wilt virus. In this disease process, you’ll also notice brown streaks on the stems, stunted or one-sided growth, and green rings on immature fruit.

This disease is spread by tiny flying insects called thrips. Check purchase plants carefully for signs of thrips and disease before bringing them home to your garden.

Practice good pest control and remove infected plants to control the spread of this disease. Resistant varieties are labeled TSWV.

Bacterial Canker disease on tomato plant leaves

Leaves with brown edges may be caused by bacterial canker. Lower leaves will also curl up and you may see light brown streaks on the stems of your plant. This disease often shows up after plants have been injured, so be careful when trimming your plants not to leave open wounds.

A note about disease resistance:

Don’t expect resistant varieties not to be affected by these diseases. Expect them to tolerate the disease. Remove and destroy affected leaves as they appear, and the plant should continue to produce fruit for you.

Yellow tomato leaves due to pests

Pests are a common cause of tomato leaf problems. They are often carriers of tomato diseases as well, so it’s prudent to keep an eye out for any insects on your tomatoes. Read about some of the bugs I’ve found in my tomatoes.

Aphids love tomato plants and cause yellow, misshapen, and sticky leaves. Look for tiny insects on the undersides of leaves and on the stem. These pests will suck the sap from your tomato plant and can be a real problem in any garden.

They can be many colors, but we often see the red/

They can be many colors, but we often see the red/pink ones. Ants love the sticky substance they excrete, and you may have an issue with both insects at the same time.

There are several options for organic aphid control including neem oil and diatomaceous earth.

Brownish, finely dotted leaves with thin webs are an indication of spider mites. Look for tiny spider-like insects on your leaves that make fine webs between and below the leaves. Infested leaves will dry up and fall off.

Spider mites and aphids can be treated with d

Spider mites and aphids can be treated with diatomaceous earth (DE). DE is a natural substance that is readily available at local garden centers.

We use a plant duster like this one to apply diatomaceous earth to affected plants. This powder will cut through the aphids’ soft exoskeletons and cause them to dehydrate and die.

Rain and watering will negate the effect of the DE so reapply as needed. Be careful to use DE in well-ventilated areas as inhaling this powder can cause damage to your lungs. And the lungs of kids, pets, and chickens, too!

If they get really bad, other forms of organic pest control including insecticidal soaps and spinosad sprays can also help.

TOMATO PESTS

INSECT PESTS OF TOMATO

Tomato hornworm, with tell-tale posterior horn and abdominal spots. Image courtesy Whitney Cranshaw — University of Colorado.

  • Hornworms

Hornworms are humungous green caterpillars that feed on the leaves in grave amounts, consuming large numbers of whole leaves. This level of defoliation can be devastating to the plants, greatly reducing productivity and yield. More mature hornworms are also known to feed on fruit. The larval droppings (frass) are often the first clues that an attack is underway.

The two hornworms that attack tomatoes are the tobacco hornworm (Manduca sexta) and the tomato hornworm (Manduca quinquemaculata). They are the larval stage in the life cycles of the Carolina sphinx moth (also known as the tobacco hawk moth) and the five-spotted hawkmoth (also known as the hummingbird or sphinx moth), respectively. In the US, the tobacco hornworm is most common in the Southeast and the tomato hornworm is most common elsewhere.

The two hornworms are very similar in appearance. The tobacco hornworm has white diagonal lines on its body, whereas the tomato hornworm has white chevrons. Additionally, the horn of the tobacco hornworm is red, whereas the horn of the tomato hornworm is black.

Hornworms can be controlled by picking the caterpillars off the leaves and destroying them; establishing colonies of natural enemies that will parasitize the caterpillars (e.g., lacewings, braconoid and trichogramma wasps, and ladybugs); or applying an insecticide, such as one that contains Bacillus thuringiensis or spinosad, both of which are acceptable for use in organic production.

  • Whiteflies

Global in distribution, there are over 1500 described species in the whitefly family, but primarily only two to three that specifically feed on the fruit and leaves of tomatoes and carry diseases such as tomato yellow leaf curl virus (TYLCV). They lay their eggs on the underside of the tomato leaves. Feeding by whiteflies is a common cause of irregular ripening disorder in greenhouse tomatoes.

  • The adult sweetpotato whitefly and the silverleaf whitefly are light in color, white to pale yellow, resembling a tiny grain of rice when viewed from above. When at rest, the powdery-white wings of the adult sweetpotato whitefly (biotype A) are held at an acute angle, peaked over its linear body. The wings of the silverleaf whitefly (biotype B), also white, are held somewhat closely to the abdomen, and the body is a more saturated yellow color. Both lay eggs that are white, turning brown as they approach hatching stage.

A combination of natural enemies, proper sanitation, and crop rotations with nonhost species, together with insecticides, such as horticultural oils, insecticidal soaps, and azadirachtin, has been shown to have some limited effect. Laying silver- or aluminum-colored mulch can also help to repel whiteflies. Prevention is critical, as a whitefly infestation can quickly snowball to the point where the only option is to destroy the crop and take the area out of production.

  • Thrips

Thrips occur through most of the US. The greatest threat that thrips pose to tomatoes is in their role as a vector of the tomato spotted wilt virus, as noted above. Their bodies are long, slender, and small, and light colored to brown. The wings of thrips have long hairs on the margins.

Prevent thrips by rotating crops and planting tomatoes away from where other host plants were previously located.

  • Aphids

There are a few main species of aphids that infest tomato plants, but the most significant are green peach aphids and potato aphids. Damage caused by aphids varies depending on the species. Interactions have been shown between aphid pre-infestation and whitefly infestation and transmission of TYLCV.

  • The green peach aphid is found worldwide, including all areas of North America, and occurs in greatest numbers early in the season. They are slender and dark-green to yellow, with darker green stripes and no waxy bloom. The damage they inflict can lead to wilting, but typically only delays maturity slightly. Green peach aphids are a known vector for viral pathogens, however.
  • The potato aphid is much larger and more elongate than the green peach aphid, and biotypes can be either green or pink in color. It is more prevalent later in the season. In great numbers, potato aphids can cause substantial damage: malformed leaves, stunted plants, and necrosis, or dead plant tissue. Their defecate, known as honeydew, can create an environment favorable to the development of mold. Ultimately, infestations can result in large yield reductions.

Aphids can be controlled with the use of natural parasitic and predatory enemies, and, as with whiteflies, repelled by the placement of reflective mulches early in the season.

  • Tomato/potato psyllid (Bactericera [Paratrioza] cockerelli)

The tomato/potato psyllid (TPP) is a member of the family sometimes referred to as the jumping plant lice. In the US, it occurs west of Mississippi. It is a small (1/8" / 3mm) pest resembling a tiny cicada, that feeds principally on solanaceous crops, though it can shelter on, or be hosted by numerous crops outside this family.

As they feed on the underside of leaves, the nymphs inject a salivary toxin that induces chlorisis and stunting of the plant’s growth tips, a condition known as psyllid yellows.

This can lead to severe wilting and stem death. The adult stage can also transmit a bacterial pathogen known as Candidatus Liberibacter solanacearum, which further compounds the damage.

Signs of an incursion by the TPP include:

  • adult psyllids, which are active fliers and jump from the foliage on disturbance;
  • the visible presence on the leaf undersides of tiny, yellow, ovoid, stalked eggs;
  • the presence of small white globs of wax-coated sap excreted by adults and nymphs, known as psyllid sugars, which in turn attract ants and mold;
  • the aforementioned stunting, yellowing, purpling, cupping, or curling of leaves;
  • severe wilting and death of plants.

If you suspect you have TPP on your property, do not spray for the pest or disturb plants until your crops have been surveyed and an appropriate treatment has been identified. There are biological and chemical control measures that can be adopted, but we advise contacting your local extension agency for assistance and reporting.

  • Potato flea beetle (Epitrix spp.)

Potato flea beetles feed upon members of the Solanaceae family. They are widespread in western North America. The flea beetle is primarily a problem at the seedling stage, when plants are most vulnerable to attack. Often clustered on the lower leaves, adult beetles chew numerous small holes in the leaves.

If flea beetles are a problem in your area, protect seedlings with floating row cover installed on the day of transplant and removed once the plant is established.

  • Tomato fruitworm (Helicoverpa zea)

Formerly of the genus Heliothis, this larva of the Helicoverpa zea moth is also known as the corn earworm and the cotton bollworm. They do not overwinter in the northern US, but they may migrate north from southern regions. The larvae enter green or ripe fruit through the stem end and feed on the fruit, making it unmarketable. At hatching, the larvae are white with a black head and black bumps, with two bristles in each bump. Older larvae vary in color from yellowish-green, green, red, and brown to nearly black, with fine spines along the body.

Releasing the tomato fruitworm egg parasite, Trichogramma pretiosum, when the fruitworms are laying their eggs, can be a helpful control measure. Planting a trap crop of silk corn can also help divert the egg-laying moths away from the tomato crop.

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NEMATODE PESTS OF TOMATO

Southern Root-knot Nematode (N) on tomato. Image courtesy Gerald Holmes — California Polytechnic State University.

Nematodes are a diverse, ubiquitous group of worms, over half of which are parasitic.

  • Root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica) • N

The species of nematodes that infect tomato plants receive their name from the galls, or knots, they cause to form on the roots. Roots with galls are less effective at taking up nutrients and water. As a result, the plants become stunted, less vigorous, and produce lower yields. Resistance to all three major nematode pests of tomatoes is very common in modern hybrids. Nematode-resistant tomato varieties…

Septoria Leaf Spot

Septoria leaf spot is aptly named because the primary symptom of the disease are the numerous brown spots that appear on the leaves, approximately 1/16 to 1/8 inch in diameter. The spots lack a yellow halo, and, upon close inspection, have black specks in the center. Unlike early and late blights, there is no stem or fruit damage.

If your tomatoes are infected, they will continue to produce fruit. Remove infected foliage immediately and disinfect your pruning tools when working from plant to plant.

To prevent the disease next year, plant your tomatoes in a different part of the garden because the fungus overwinters on infected tomato debris and in the soil, Purchase disease-resistant varieties, do not water overhead, use mulch to prevent soil from splashing up on foliage, and increase air circulation between plants.

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