Early blight on tomatoes is a fungal disease that shows up as small brown spots with concentric rings on the oldest, lowest leaves, then works its way up the plant over several weeks rather than days. It rarely kills a healthy tomato outright, but left alone it strips enough foliage to expose fruit to sunscald and cut your harvest hard. Right now, walk to the base of the plant, turn over the lowest leaves, and look for that bullseye pattern before you decide this is early blight and not something faster and worse.
What you are looking at
Early blight is slow but persistent, moving through a planting over weeks rather than overnight. It almost always starts at the bottom of the plant, on the oldest leaves nearest the soil, because that is where fungal spores splashed up from the ground first land. If your tomato looks fine at the top and spotty at the bottom, that pattern alone points toward early blight before you even look closely at a single lesion.
The oldest leaves first
The earliest sign is a scatter of small dark spots on the lower, older foliage, usually appearing once the plant is carrying fruit and the lower leaves have started to show some natural stress. These spots are easy to dismiss as nothing at first because they start so small.
Concentric rings up close
Look closer and each spot reveals a target pattern: distinct rings inside the lesion, running from a darker outer edge to a lighter brown center, often with a thin yellow halo where the dead tissue meets living leaf. This ringed look is the single most reliable visual marker of early blight and the detail that separates it from most other leaf spot diseases.
Stem cankers and fruit rot
As the disease progresses, lesions can appear on stems as dark, sunken cankers, sometimes girdling a young seedling stem at the soil line in a problem called collar rot. On fruit, the disease produces leathery, sunken, dark patches at the stem end, usually on green fruit still on the vine, and these patches carry the same concentric rings seen on the leaves.
What it is not
Three other tomato problems get mistaken for early blight often enough that the mix-up is the real risk, not the disease itself. Treating a fast-moving problem as though it were a slow one costs you the whole planting.
Septoria Leaf Spot
Septoria also starts on the lower leaves and also causes multiple small spots, which is why the two get confused constantly. The difference is size and pattern: septoria spots stay much smaller, rarely bigger than a pencil eraser, have no concentric rings, and show tiny black specks in the center of each spot under a hand lens. Read more about the distinction on our page covering tomato diseases broadly if you are trying to sort out which leaf spot problem you are actually managing.
Late Blight
This is the mix-up that matters most. Late blight lesions are irregular and water-soaked, not ringed, and they can cover a leaf and spread through a planting within days rather than weeks. If you see a fuzzy white mold on the leaf underside in the cool of the morning, or lesions expanding fast enough to notice a difference day to day, stop what you are doing and read Late Blight on Tomatoes: How to Recognise It Before It Takes the Whole Row. Treating late blight as though it were the slower early blight can cost you the entire row in the time it takes to plan a response.
Fusarium Wilt
Fusarium wilt produces no leaf spots whatsoever. Instead you get wilting confined to one side of the plant or a single branch while the rest of the plant looks normal, and a lengthwise cut through the stem reveals a brown ring of discolored vascular tissue. If your plant is wilting rather than spotting, and the wilt is lopsided, you are looking at something described on our page about Fusarium Wilt on Tomatoes: When One Side of the Plant Goes First, and no amount of fungicide aimed at early blight will help it.
Where it comes from and when it strikes
Early blight is caused by a fungus in the genus Alternaria, and it survives between growing seasons in infected plant debris left in the soil, on the surface of stakes and cages that were not cleaned, and occasionally on seed. Once the season starts, spores splash up from that residue onto the lowest leaves during rain or overhead watering, which is why the disease so reliably begins at the bottom of the plant rather than the top.
From there, spores spread short distances by wind and rain splash to neighboring plants and to higher leaves on the same plant. The fungus favors warm conditions paired with extended periods of leaf wetness, whether from rain, heavy dew, or overhead irrigation that keeps foliage damp for hours at a stretch. Plants under stress from heat, drought, or heavy fruit load are more vulnerable, since stressed and aging tissue is easier for the fungus to colonize than vigorous new growth. Prolonged leaf wetness, not any single temperature spike, is the condition that lets an early infection turn into a serious one, which is why gardens with dense foliage and poor air movement tend to see it worst.
What to do about it now
Start by removing the worst-affected lower leaves, cutting them off rather than pulling to avoid tearing healthy tissue, and bag them for the trash instead of the compost pile since home compost rarely gets hot enough to kill the spores. This will not undo damage already done, but it slows the supply of new spores splashing onto healthy foliage above.
Stop watering overhead if you have been, and switch to a soaker hose or drip line aimed at the soil rather than the leaves. Add a layer of mulch, straw or shredded leaves work well, under the plant to act as a physical barrier between soil-borne spores and the lowest leaves. Prune out suckers and lower branches below the first fruit cluster to open up airflow through the canopy, since foliage that dries out quickly between waterings gives the fungus less opportunity to establish.
Fungicide and harvest safety
A protectant fungicide, such as one containing chlorothalonil or copper, or a biological option based on Bacillus subtilis, can slow the spread of new infections when applied before lesions cover much of the plant, but none of these products reverse damage already present on a leaf. They are a brake, not a cure. The fruit itself is safe to eat even from an infected plant. Cut away any sunken lesion on an individual tomato and use the rest as normal.
Keeping it out next season
Rotation matters because the fungus persists in soil-borne plant debris for longer than a single season, so plan to keep tomatoes, and their nightshade relatives peppers, potatoes, and eggplant, off the same bed for a multi-year stretch rather than moving them next door. Check with your local extension service for a rotation length suited to your soil and climate, since how long the fungus remains viable varies with conditions.
Several tomato cultivars carry documented resistance or tolerance to early blight, marked on seed packets with the letters EB. ‘Mountain Magic‘ and ‘Iron Lady’ both list resistance codes covering early blight, late blight, and septoria leaf spot (EB, LB, SLS) together, which is useful if more than one of these has shown up in your garden. ‘Defiant PhR‘ pairs early blight tolerance with strong late blight resistance, and ‘Plum Regal‘ is a paste tomato bred specifically with early blight resistance in mind. These letter codes are printed on the seed packet or catalogue listing and hold regardless of where you garden.
Sanitation and sourcing
- Clean stakes, cages, and tomato clips at the end of the season with a diluted bleach or hydrogen peroxide solution rather than storing them dirty
- Remove and discard all tomato plant debris from the bed in fall instead of tilling it under
- Space plants further apart than feels necessary and prune for airflow through the canopy
- Buy transplants from a source that inspects for disease, or start your own seed to control what enters the bed
- Keep mulch on the soil surface from transplant onward as a standing splash barrier
None of these steps guarantee a disease-free season on their own, but stacked together they cut both the spore load waiting in the soil and the conditions the fungus needs once the season starts.
Common questions
Can early blight kill my tomato plant?
On its own, rarely. It weakens the plant by destroying foliage over time, which reduces yield and exposes fruit to sun damage, but a mature plant usually survives the season. A young seedling hit hard by a stem canker near the soil line is more vulnerable and can die.
Is it too late to spray once I see spots?
Fungicide sprayed after spots appear will not remove existing lesions, but it can still protect the healthy leaves that have not been infected yet. The earlier you catch it and start protecting new growth, the more foliage you save for the rest of the season.
Can I still eat tomatoes from a plant with early blight?
Yes. Cut away any sunken or discolored spot on the fruit itself and the rest of the tomato is fine to eat. The disease affecting the leaves does not make the unaffected fruit unsafe.
Why does it always start on the bottom leaves?
Because the fungus overwinters in soil-borne debris and spreads upward from there when rain or irrigation splashes spores onto the leaves closest to the ground. That is also why mulch and drip irrigation, which keep water and soil from splashing onto foliage, are two of the most effective preventive steps you can take.