Tomatoes diseases and pests
The database lists 7 problems recorded on this crop. 4 of them can cost the whole harvest, and 5 survive in soil or debris into next season — those are the ones that decide your rotation. The largest number are active in June.
Pressure through the year
The number of problems listed as active in each month. Pick a month to see what to sow, plant and harvest then.
Start from what you can see
What actually prevents them
Water at the base of the plant in the morning, never over the leaves. Splashing soil onto foliage is the delivery route for every problem listed here, and morning watering lets anything that does land dry before nightfall.
Applies to: Early Blight, Septoria Leaf Spot, Leaf Mold
Mulch the soil surface. A physical barrier between last season's spores and this season's lowest leaves removes the first infection of the year, which is the one that seeds all the others.
Applies to: Early Blight, Septoria Leaf Spot, Leaf Mold
Give the plants their full spacing 45×75 cm and keep the centre of each one open. Air moving through the planting dries the leaves faster, and leaf wetness duration is what turns a spore landing into an infection.
Applies to: Late Blight
Rotate this bed and everything else in the same family on at least a three-year cycle. 5 of the problems below survive in soil or crop debris between seasons, so returning the same crop to the same ground hands them the host they were waiting for.
Applies to: Fusarium Wilt, Late Blight, Early Blight, Septoria Leaf Spot and 1 more
Clear and remove the spent crop at the end of the season rather than digging it in. Debris left on the surface is where the persistent problems overwinter, and next spring they start from your own bed rather than from somewhere else.
Applies to: Fusarium Wilt, Late Blight, Early Blight, Septoria Leaf Spot and 1 more
Keep watering and feeding even rather than generous. Several problems on this list are not infections at all: they are the plant reacting to a swing in water, temperature or nutrient supply, and consistency prevents them where no spray can.
Applies to: Blossom Drop, Blossom End Rot
Keep affected material out of the compost heap — 4 of these survive a garden heap and come back with the finished compost. Bag it for municipal green waste, which is composted at temperatures a garden heap does not reach.
Applies to: Fusarium Wilt, Late Blight, Early Blight, Septoria Leaf Spot
Every listed problem
Ordered by how much they can cost you.
Fungal diseases(5)
- Fusarium WiltCritical
Yellowing and wilting often on one side of the plant or one branch, progressing upward; brown discoloration inside the lower stem when cut; eventual collapse despite moist soil.
- How it spreads
- Soil and crop debris
- Compost
- Keep out of the compost
- Conditions
- 25–34°C · humidity ≥60%
- First move
- Remove affected material now
Also at risk: Basil
- Late BlightCritical
Dark, water-soaked greasy patches on leaves that rapidly turn brown; white fuzzy sporulation on leaf undersides in humid mornings; firm brown lesions on stems and fruit. Whole plants can collapse within days.
- How it spreads
- Wind-blown spores
- Compost
- Keep out of the compost
- Conditions
- 10–25°C · humidity ≥90% · wet leaves / rain
- First move
- Remove affected material now
Also at risk: Potatoes
- Early BlightSevere
Brown spots with concentric rings forming a target or bullseye pattern, surrounded by yellow halos, on older lower leaves first. Severe defoliation and dark leathery lesions near the stem end of fruit.
- How it spreads
- Rain and irrigation splash
- Compost
- Keep out of the compost
- Conditions
- 20–32°C · humidity ≥75% · wet leaves / rain
- First move
- Treat, then re-check in 5–7 days
Also at risk: Potatoes
- Septoria Leaf SpotSevere
Many small circular spots with dark borders and pale grey centres, often dotted with tiny black fruiting bodies, starting on the lowest leaves after fruit set.
- How it spreads
- Rain and irrigation splash
- Compost
- Keep out of the compost
- Conditions
- 20–26°C · humidity ≥90% · wet leaves / rain
- First move
- Treat, then re-check in 5–7 days
- Leaf MoldModerate
Pale green to yellow blotches on the upper leaf surface with olive-green to brown velvety mould on the underside; leaves curl, brown and drop, starting low in the canopy.
- How it spreads
- Rain and irrigation splash
- Compost
- Hot compost only
- Conditions
- 18–27°C · humidity ≥85% · wet leaves / rain
- First move
- Treat, then re-check in 5–7 days
Physiological disorders(2)
- Blossom DropModerate
Flowers yellow at the base of the stalk and drop off complete, leaving a bare truss with no fruit set. It happens in waves that match a heatwave or a cold snap a week or so earlier, while the plant itself looks perfectly healthy.
- How it spreads
- Not contagious
- Compost
- Safe to compost
- Conditions
- ≥32°C · dry air ≤40%
- First move
- Watch it before you act
Also at risk: Peppers
- Blossom End RotModerate
A sunken, leathery, dark brown-black patch at the blossom (bottom) end of the fruit, often on the first fruit of the season or during dry spells; the rest of the fruit may ripen normally.
- How it spreads
- Not contagious
- Compost
- Safe to compost
- Conditions
- Spread by handling, insects or soil — not weather-triggered
- First move
- Fix the cause, not the leaf
Also at risk: Peppers, Aubergines
Why rotation matters here
5 of these overwinter in the soil or in crop debris rather than on the plant. Pulling the sick plant does not remove them: they wait for the same host to come back to the same ground.