Demystifying Tiny Black Spots on Cherry Tomatoes

As gardeners, few things delight us more than harvesting lush, ripe cherry tomatoes straight from the vine. But that joy can quickly turn to dismay when those brilliant red globes are marred by strange black spots. If you’ve noticed tiny black spots marring the skin of your cherry tomatoes, you’re not alone. Many tomato growers encounter this issue. While the spots may look harmless, they can potentially indicate some serious tomato troubles. This guide covers the common causes of black spots on cherry tomatoes and what you can do about them.

What Causes Tiny Black Spots on Cherry Tomatoes?

Several culprits can lead to small black spots on ripe cherry tomato fruits including

  • Bacterial canker – Caused by the bacterium Clavibacter michiganensis, this disease leads to small black spots that often have light centers, giving a “bird’s eye” appearance. Very destructive disease.

  • Early blight – Fungal disease favored by wet conditions. Causes dark leathery spots on leaves and fruits. Spots on fruits are typically large.

  • Blossom end rot – Abiotic disorder caused by calcium deficiency. Leads to sunken black spots on tomato bottoms.

  • Physiological flecking – Abiotic disorder causes tiny dark flecks on skin. Worsens with over-fertilization and extreme temperatures. Harmless.

  • Insect damage – Feeding by stink bugs leaffooted bugs, and others leads to dark spots where they penetrate fruits.

  • Sunscald – Exposure to intense sun can blister fruits, which then form black scabby spots Worst on exposed fruits.

  • Environmental factors – Wind, hail, lawn mower damage, etc. can also mechanically damage fruits, allowing decay fungi to create spots.

How to Identify and Treat Black Spot Causes

Accurately diagnosing the cause of black spots allows you to take appropriate action:

Bacterial canker – One of the most destructive tomato diseases. Look for numerous tiny black spots with light gray centers scattered over ripe fruits. Sunken black lesions may also appear on stems.No cure exists. Remove and destroy affected plants immediately to avoid spread. Disinfect any tools used on plants.

Early blight – Irregular dark leathery spots enlarge to form concentric rings. Most severe on leaves but also affects fruits and stems. Use disease-resistant varieties and fungicides. Avoid overhead watering.

Blossom end rot – Sunken black lesion occur on tomato bottoms. Caused by calcium deficiency. Consistent watering can help. Adding calcium supplements may help.

Physiological flecking – Tiny dark speckles on fruits surface. Worsens with over-fertilization and temperature extremes. Harmless and unpreventable. Don’t over-fertilize.

Insect damage – Look for insect pests on plants and fruits. Control them with appropriate organic or conventional insecticides.

Sunscald – Sunken, blistered black spots on exposed fruits. Prevent by avoiding over-pruning plants and providing afternoon shade.

Mechanical damage – Cracks, scrapes, indentations allow decay fungi to create spots. Avoid damaging fruits and stems.

Best Practices to Minimize Black Spots on Tomatoes

While some causes of black spots on cherry tomatoes can’t be prevented, following best practices will minimize many issues:

  • Select disease-resistant tomato varieties when possible. Look for resistance to common diseases like early blight.

  • Rotate tomato planting beds each year to reduce disease carryover in soil.

  • Stake or cage tomato plants and prune selectively to improve air circulation.

  • Water at the soil line instead of overhead watering to reduce fungal and bacterial spread.

  • Apply mulch around plants to prevent soil splashing onto leaves and fruits.

  • Scout plants frequently and remove any diseased or insect-damaged leaves, stems, or fruits.

  • fertilize tomatoes based on soil test recommendations to avoid excess fertilizer.

  • Use row covers or shading in intense sunlight to prevent sunscald.

  • Handle fruits gently to avoid bruising or damaging the delicate skin.

When to Accept and When to Worry

As disheartening as black spots on ripe tomatoes can be, it’s important to accept some imperfection, especially with susceptible heirloom varieties. However, if spots are very numerous, enlarging quickly, or combined with wilting leaves, it likely indicates a disease like bacterial canker that requires swift removal of plants to protect other tomatoes. When in doubt, seeking expert diagnosis from your local extension office can identify if action is needed. Don’t let a few tiny black spots ruin your enjoyment of sweet cherry tomato harvests!

What is causing black spots on my tomatoes?

I grow Juliet tomatoes each year primarily for fresh eating and freezing for sauce. This year I planted late due to weather. Of interest, I use no chemicals/sprays etc, only addition is bone meal. What are the black spots on the plants, and is it safe to freeze or process them? Also, should I do something to the soil in my beds?

Answer:Jonathan Foster, Special Projects Assistant

I’m sorry to be the bearer of bad news, but your tomatoes appear to be infected with anthracnose, a fungus-caused ailment of the fruit. The sunken spots are a tell-tale sign. The fruit should be ok to eat if no symptoms have developed, and we recommend harvesting slightly before full ripeness and eating the fruit just as soon as it’s ready. Sources vary on whether it’s safe to eat fruit if infected portions are cut away (contrast with the link below), so I would try to eat them fresh and unblemished if at all possible. I wasn’t entirely sure about the potential for freezing such infected fruits safely, though, so I reached out to Dr. Beth Calder, a UMaine Cooperative Extension professor and an expert on food safety. Her reply: “I like the advice from this Lancaster Farming article: https://www.lancasterfarming.com/country-life/gardening/is-that-tomato-rotten-or-is-it-safe-to-eat/article_41c8278a-35f6-11ee-8f76-c753548c4540.html. Although the spot itself may not be a potential food safety problem, a blemish or crack can certainly allow for potential pathogens to enter the produce and that could be a potential food safety problem. It would be safer to throw away diseased produce.” Tragic news for your harvest, but it’s better to be safe than sorry…. For next year, you will want to practice crop rotation and plant your tomatoes in a different location, as the pathogen can overwinter in your soil. As you will read in the Clemson link above, there are also chemical treatments available if you choose to go that route. Best practices for tomatoes will help, too–consistent irrigation, well-drained soil, watering the soil rather than overhead through the leaves, pruning the plants to allow airflow at the base, and promptly disposing of any debris (no composting, as any fruit tissue that survives may carry the spores). Your goal is to prevent warm, moist, still air from sitting among the leaves, which promotes growth of all fungal pathogens (anthracnose among them).

Black Spots on Tomato Leaves Causes and Solutions

FAQ

Can you eat tomatoes with bacterial speck?

DO NOT eat symptomatic fruit. Although the bacterial speck pathogen is not a human pathogen, the fruit blemishes that it causes can provide entry points for human pathogens that could cause illness.

Are tomatoes with small brown spots safe to eat?

If small, sunken spots or what looks like bruises appear on your ripe tomatoes, that’s anthracnose. This fungus emerges as the weather gets hot and humid – usually 80° or warmer. So, harvest ripe tomatoes as soon as possible. These are safe to eat if you cut off the bruises.

What is a home remedy for black spots on tomatoes?

If you garden organically, adding compost extracts or teas can be a treatment. To create a solution that prevents and treats disease, add a heaping tablespoon of baking soda, a teaspoon of vegetable oil, and a small amount of mild soap to a gallon of water and spray the tomato plants with this solution.

What are the black rot spots on tomatoes?

Dark blotches on the ends of aubergine, tomato and pepper are alarming, but do not mean the end of the crop. This is called blossom end rot and is caused by lack of calcium in the fruits. By making minor adjustments in watering you will usually be able to protect subsequent fruits from blossom end rot.

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