Septoria leaf spot is a very common tomato disease. It is caused by a fungus (Septoria lycopersici) and can affect tomatoes and other plants in the Solanaceae family, especially potatoes and eggplant, just about anywhere in the world.
Although Septoria leaf spot is not necessarily fatal for your tomato plants, it spreads rapidly and can quickly defoliate and weaken them, rendering them unable to bear fruit to maturity. Septoria leaf spot causes black spots on tomato leaves with small fruiting bodies (raised bumps) in the center, resulting in yellow leaves that eventually turn brown and die.
Learn what Septoria leaf spot is and how to identify, treat, and prevent it when growing tomatoes.
As a gardener and tomato enthusiast, few things delight me more than harvesting plump, juicy cherry tomatoes fresh from the vine. However, that joy can quickly turn to dismay when those brilliant red beauties are marred by strange tiny black spots. If you’ve noticed these perplexing spots popping up on your cherry tomatoes, don’t fret – you’re not alone. Many tomato growers encounter this pesky issue. While the spots may look harmless, they can potentially indicate some serious problems with your cherished tomato plants. Read on as we demystify the common causes of those tiny black spots on cherry tomatoes and explore what you can do to prevent and treat them.
What’s Causing Those Taunting Tiny Black Spots?
When it comes to garden puzzles getting to the root cause is half the battle. In the case of small black spots marring ripe cherry tomato fruits several usual suspects are at play
-
Bacterial canker – Caused by the bacterium Clavibacter michiganensis, this destructive disease leads to numerous tiny black spots, often with light centers giving a “bird’s eye” look It can completely decimate a tomato crop if left unchecked
-
Early blight – A fungal disease favored by wet, humid conditions. It causes dark leathery spots that can start on leaves and spread to fruits. Spots are typically large and irregular.
-
Blossom end rot – Caused by calcium deficiency, this disorder creates sunken black spots on the bottom of tomatoes, known as the blossom end.
-
Physiological flecking – An abiotic, or non-infectious, disorder triggered by over-fertilization, extreme temps, etc. It causes tiny dark speckles on the fruit skin but doesn’t affect quality.
-
Insect damage – Feeding by pests like stink bugs and leaffooted bugs can leave behind dark spots where they penetrate the fruit skin.
-
Sunscald – Exposure to intense sunlight can cause blistering and scabby black spots on exposed tomato fruits.
-
Mechanical damage – Impacts, scrapes, or cuts from wind, hail, lawn mowers, etc allow fungi and bacteria to invade, resulting in black spots.
Accurate Diagnosis Is Key
When facing down tiny black spots on your coveted cherry tomato crop, accurately diagnosing the cause is critical for taking appropriate action:
-
Bacterial canker – Numerous tiny black spots with light centers scattered on fruits point to this destructive disease. Swift removal of affected plants is needed to protect remaining tomatoes.
-
Early blight – Look for the characteristic dark, enlarging lesions with concentric rings mostly on leaves but also fruits. Resistant varieties and fungicides can help control it.
-
Blossom end rot – The telltale sunken black spots on the bottom of fruits signals a calcium deficiency. Boost calcium and maintain even soil moisture.
-
Physiological flecking – Harmless tiny dark speckles that worsen with overfeeding. Don’t overdo the fertilizer.
-
Insect damage – Look for bugs! Control tomato pests with organic or conventional insecticides.
-
Sunscald – Sunken black blisters on exposed fruits. Prevent by providing afternoon shade.
-
Mechanical injury – Cracks, scrapes and bruises allow decay fungi to move in. Handle fruits gently.
Battling Tiny Black Spots: Prevention and Treatment
While some causes of tiny black spots on cherry tomatoes can’t be prevented, proactive care will help avoid many issues:
-
Choose disease-resistant varieties when possible. Prioritize resistance to fungal diseases like early blight.
-
Rotate planting sites each year to reduce pathogen levels in soil.
-
Stake or cage plants to improve airflow and reduce fungal issues.
-
Avoid overhead watering which spreads pathogens – use drip irrigation or direct water to soil.
-
Apply organic mulch to prevent soil from splashing onto leaves and fruits during watering.
-
Scout for diseased or insect damaged leaves/fruits and remove promptly.
-
Have soil tested and fertilize carefully based on recommendations.
-
In intense sunlight, use row covers or shading fabrics to prevent sunscald.
-
Handle fruits with care to avoid bruising delicate skin and flesh.
With attentive prevention and early detection, those tiny black spots don’t stand a chance against your cherry tomato greatness. Don’t let a few blemishes stop you from enjoying the sweet harvests these plants provide. Stay vigilant and be proactive, and you’ll master those tiny black spots in no time!
Start With a Clean Garden
Dispose of all affected plants. The fungus can overwinter on the debris of diseased plants, so its important to dispose of all the affected plants far away from the garden and the compost pile. Keep in mind that it may have spread to your potatoes and eggplants, too. Cage tomatoes (disinfect cages yearly) to prevent leaves from touching the ground or other plants.
How to Treat Septoria Leaf Spot
There are a few options for treating Septoria leaf spot when it appears; these include:
Black Cherry Tomatoes #garden #gardening
FAQ
Is it safe to eat tomatoes with tiny black spots?
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 …Oct 17, 2023
What are the spots on my cherry tomatoes?
Quickly distinguishing between types of brown spots is crucial. Rusty patches often point to nutrient deficiencies, while circular lesions with dark rings are telltale signs of a fungal invasion. Spots with a water-soaked look suggest bacterial issues, whereas dry spots could be environmental stress.
Are tomatoes with bacterial speck safe to eat?
One last point – if you do end up seeing spots on the tomatoes it is recommended that you not eat these. While the 2 bacteria that cause bacteria leaf spot or leaf speck do not cause disease, the holes they make in the tomato skin could allow human pathogens to enter the fruit.
Why are my cherry tomatoes speckled?
The blotchy ripening (that’s what it is called) on the fruit is caused by the loss of leaves and fruit getting too much sun. The plant is stressed and the excess sun causes it to happen. Keeping healthy leaves on the plant can prevent this.