Got tomatoes growing in your backyard?
In a perfect world, they’ll flourish without a hiccup. But more often than not, tomatoes run into a little trouble as they grow.
Leaves may turn yellow, pests might cause damage, or the fruit can split!
But don’t worry — many of these issues can be avoided or managed with the right preparation and care.
Here’s a guide to the most common tomato problems in Australia, plus tips on how to solve (or prevent) them.
Fungal Diseases | Bacterial Diseases | Viral Diseases | Common Pests | Fruit Problems | Nutrient Deficiencies | Prevention Tips
Common Tomato Plant Problems in Australia
Tomatoes can be prone to diseases, pests, and other issues if they’re not grown in the right conditions.
If something’s off with your tomatoes, you’ll usually notice it first in the leaves. They may turn yellow or develop dark spots.
The fruits can also be deformed or have blemishes.
This chart can help you identify what’s wrong with your tomato plants:
| CATEGORY | PROBLEM | SIGNS |
| FUNGAL DISEASES | Fusarium wilt Southern blight Verticillium wilt |
Yellowing and wilting leaves; sudden plant collapse |
| Septoria leaf spot Early blight |
Brown spots, yellowing leaves | |
| Powdery mildew | White coating on leaves | |
| Late blight | Pale green patches and white mould on leaves | |
| BACTERIAL DISEASES | Bacterial speck | Leaf spots; specks on fruit |
| Bacterial wilt Tomato pith necrosis |
Yellowing leaves; sudden wilting | |
| VIRAL DISEASES | Tobacco mosaic virus Tomato brown rugose fruit virus Tomato spotted wilt virus Tomato yellow leaf curl virus |
Mottled, curled leaves; misshapen fruit |
| PESTS | Caterpillars | Chewed leaves, fruit holes |
| Root knot nematodes | Stunted plants | |
| Sap-suckers (aphids, mites, thrips, or whiteflies) | Sticky coating on leaves; bugs on leaf undersides | |
| FRUIT ISSUES | Blossom end rot | Dark patch on the bottom of the fruit |
| Cracks or splitting | Cracked fruit | |
| Catfacing | Misshapen fruit | |
| Sunscald | White patches on fruit | |
| NUTRIENT DEFICIENCIES | Deficiencies (Ca, Mg, N, P, K) | Discoloured leaves; fruit deformities |
Below, we’ll explain each problem in detail and share the best ways to manage it!
Fungal Tomato Diseases in Australia
Tomato plants are more susceptible to fungal diseases during rainy weather.
To avoid outbreaks, maintain good air circulation between your tomatoes. Space plants about 75–100cm apart, and prune them regularly.
Many fungi also live in the soil, so practice crop rotation.
Once you’ve grown tomatoes or other nightshades in a patch, wait 3–4 years before planting them again in the same area.
This prevents the buildup of disease-causing organisms in the soil.
NOTE: Soil-borne pathogens can affect many types of plants, not just nightshades. Always check if a plant is susceptible to the same infection before planting!
Fusarium wilt
| SIGNS | Yellowing leaves on one side or branch of the plant |
| TREATMENT | No cure — remove affected plants immediately |
Fusarium wilt is a tomato disease caused by a soil-borne fungus (Fusarium oxysporum f. sp. lycopersici).
It enters through the roots, then moves up and clogs the plant’s vessels — cutting off water and nutrient supply.
When that happens, you might see yellowing tomato leaves, usually on one side or branch. Eventually, the whole plant wilts and dies.
There’s no cure for Fusarium wilt. Remove and dispose of infected plants in a sealed bag — do not compost them!
Powdery mildew
| SIGNS | White, powdery coating on tomato leaves |
| TREATMENT | Prune affected leaves; use a sulphur spray |
Powdery mildew is a fungal problem that causes a white, powdery coating on tomato leaves.
As the fungus spreads, the leaves turn yellow and eventually drop. Tomato fruits are rarely affected, but you might get a smaller harvest.
To manage powdery mildew, prune infected leaves right away.
Then, treat the remaining leaves with a sulphur spray — follow the directions on the product label.
Septoria leaf spot
| SIGNS | Spots on leaves with a brown margin and a light grey centre |
| TREATMENT | Prune affected leaves; use a copper-based fungicide |
Septoria leaf spot (caused by Septoria lycopersici) is a fungal disease that usually shows up in wet weather.
It starts in the lower leaves as small brown spots with a lighter grey centre and a yellow halo.
Later, those spots can merge, which causes the leaves to shrivel and fall off.
If the symptoms reach the upper leaves, affected plants might lose all their leaves and die.
At the first sign of Septoria leaf spot, prune infected leaves immediately.
Then, use a copper-based fungicide with mancozeb or chlorothalonil. Check the label for directions on how to apply it.
Southern blight
| SIGNS | Affected tomatoes suddenly wilt and die |
| TREATMENT | No cure — remove the affected plant and soil right away |
Southern blight is caused by a soil-borne fungus (Sclerotium rolfsii). In Australia, it’s usually found in tropical and subtropical areas like the NT, QLD, and WA.
The fungus attacks the tomato’s stem right at the soil line. It instantly blocks water and nutrient flow, so the affected plant suddenly wilts and dies.
The infection leaves a dark patch on the stem. You might also see a white, web-like growth around the base of the plant and over the soil surface.
Make sure to pull out and dispose of infected tomato plants, along with the surrounding soil.
Wait 3–4 years before planting tomatoes or other nightshades in the same patch to give the fungus enough time to die off.
Tomato early blight
| SIGNS | Brown spots on leaves that form a bullseye pattern Yellowing, wilting, and falling leaves |
| TREATMENT | No cure; remove affected plants immediately |
Despite the name, “early” blight usually attacks mature tomato plants.
It’s caused by the fungus Alternaria solani, which thrives in warm, moist weather.
Early blight starts as small, brown spots on the lower leaves, which later develop into a bullseye pattern.
The fruits can also be affected with the same brown spots and concentric rings.
As the disease progresses, the symptoms move upwards. Leaves also become yellow, dry up, and drop.
There’s no cure for early blight, so remove and dispose of infected plants immediately.
Tomato late blight
| SIGNS | Watery, pale green patches on leaves and stems Affected fruits rot quickly |
| TREATMENT | No cure — call the local agriculture hotline |
Late blight, caused by Phytophthora infestans, is one of the world’s most destructive tomato diseases.
It’s rare in Australia due to strict control measures, but it’s still worth knowing the signs.
Look for pale green, water-soaked patches on tomato foliage and stems, and a fuzzy white mould on the underside of the leaves.
Tomato fruits may also develop dark blotches and rot fast.
If you think your plants may have late blight, call your local agriculture department right away!
Verticillium wilt
| SIGNS | V-shape yellowing on tomato leaves |
| TREATMENT | No cure; remove affected plants immediately |
Verticillium wilt is a serious tomato problem caused by the fungus Verticillium dahliae or V. albo-atrum.
It can linger in the soil for years and is usually found in garden beds where other nightshades have grown.
The lower leaves also turn yellow, following a V-shape pattern. Later, upper leaves develop the same discolouration.
As the disease advances, the entire plant can wilt and collapse. There’s no cure, so remove infected plants straight away.
Also, practice crop rotation to help keep the soil healthy.
Bacterial Tomato Diseases in Australia
Aside from fungal problems, tomatoes can also be prone to bacterial diseases.
These diseases easily spread through moisture, so avoid overhead watering or handling wet plants.
Also, space tomato plants properly to avoid leaf contact and control the spread of bacteria.
Bacterial speck
| SIGNS | Dark brown to black spots on leaves with yellow halos Raised black specks on unripe fruits |
| TREATMENT | No cure – remove infected tomatoes right away |
Bacterial speck is a common tomato plant disease that can reduce yield and fruit quality.
Once tomatoes are infected, the leaves develop small dark spots with yellow halos. Eventually, they die off and fall.
You’ll also find slightly raised black specks on green fruits, which sink as the tomatoes ripen.
Bacterial speck cannot be cured. Once you see any signs of the infection, remove the affected tomato plants right away.
Bacterial wilt
| SIGNS | Infected tomatoes suddenly wilt and die off |
| TREATMENT | No cure – remove affected tomatoes right away |
Bacterial wilt is a highly destructive tomato disease caused by the soil-borne bacterium Ralstonia solanacearum.
It attacks the plant’s vessels and blocks water and nutrients, so affected tomatoes wilt and die without warning.
If you slice the lower stem, you’ll see a brown streak inside, along with a whitish ooze.
Bacterial wilt cannot be treated, so you’ll need to remove the entire plant once it’s infected.
For prevention, grow tomato varieties that are resistant to bacterial wilt.
Tomato pith necrosis
| SIGNS | Upper tomato leaves turn yellow and wilt |
| TREATMENT | No cure – remove affected plants right away |
Tomato pith necrosis is caused by soil-borne Pseudomonas bacteria. They infect tomatoes through wounds or openings in the lower stem or roots.
This disease usually affects mature plants just as they start producing fruit.
Symptoms first appear on the upper portion of the plant, with yellowing and wilting leaves.
There’s no treatment for tomato pith necrosis.
To prevent it, avoid feeding tomatoes too much nitrogen. That can weaken the plant tissues and make them more susceptible to infection.
Viral Tomato Diseases in Australia
Viruses can cause serious issues in tomato plants. Unfortunately, there’s usually no cure once they show up.
To be safe, always buy tomato seeds or seedlings from a reliable garden centre to make sure they’re disease-free.
If you think your tomatoes are infected by a virus, notify your local agriculture department right away.
Tobacco mosaic virus
| SIGNS | Mottled, distorted, fern-like leaves Uneven ripening of fruits |
| TREATMENT | No cure – focus on prevention |
Tobacco mosaic virus (TMV) — the first ever virus to be discovered — affects more than 350 plant species, including tomatoes.
It’s closely related to tomato mosaic virus or TOMV, which causes similar symptoms.
Once infected with TMV, tomato leaves develop a light to dark green, mosaic-like mottling. They also become distorted and start looking like a fern.
Fruits ripen unevenly and may have discoloured blotches and streaks, so they’re unsuitable for eating.
There’s no cure for TMV, so remove diseased plants immediately!
Also, do not smoke or carry tobacco products near your vegetable garden. They might contain TMV particles that can infect the plant.
Tomato brown rugose fruit virus
| SIGNS | Yellow, mottled or rugose (wrinkled) leaves Deformed fruit with rough patches or spots |
| TREATMENT | No cure – focus on prevention |
Tomato brown rugose fruit virus (or ToBRFV) is a highly infectious tomato disease.
In Australia, it was first detected in SA in 2024. Within months, it spread to VIC and NSW.
Some farms lost up to 70% of their crops, which led to tomato shortages and higher prices nationwide.
ToBRFV causes misshapen fruits and uneven ripening. They’ll also have rough patches and brown or yellow spots, so they’re unsuitable for sale or eating.
The virus spreads mainly through infected tomato seedlings or seeds. But it can also be passed on through gardening tools, hands, or leaf-to-leaf contact.
Since ToBRFV cannot be cured, prevention is key. Always buy your tomato seeds from a reliable garden centre, and be wary of imported plants.
Tomato spotted wilt virus
| SIGNS | Mottled, browning leaves that curl upwards Discoloured blotches on fruits |
| TREATMENT | No cure – focus on prevention |
Tomato spotted wilt virus (TSWV) is transmitted by thrips, which are tiny sap-sucking insects.
Infected tomato plants show brown, mottled, or spotted leaves that curl upwards. Stems also develop dark streaks.
Additionally, the fruits can be marked with concentric rings or blotches that could be yellow, green, or brown.
There’s no cure for TSWV, so the best approach is to keep thrips under control through good pest management.
Tomato yellow leaf curl virus
| SIGNS | Leaves grow smaller, turn yellow, and curl Plants fail to flower and fruit |
| TREATMENT | No cure – focus on prevention |
Tomato yellow leaf curl virus (TYLCV) is a damaging tomato virus that can reduce yields. It’s spread by silverleaf whiteflies, a sap-sucking pest.
Usually, young tomato plants are affected. Once they have the virus, their leaves grow smaller than usual, then turn yellow and curl upwards.
The virus also stunts plant growth, and prevents flowering and fruit set.
In Australia, TYLCV is not a major concern right now. Still, it’s considered a serious threat to tomatoes and other nightshades.
Tomato Pests in Australia
Tomatoes can be susceptible to pests, which can damage the leaves and fruits.
To prevent a heavy infestation, monitor your plants often. That way, you can catch any bugs early.
Also, try growing tomato companion plants with natural pest-repelling abilities, like basil and parsley.
Caterpillars
| SIGNS | Chewed leaves Holes in tomato fruits |
| TREATMENT | Handpicking Using organic sprays with Bt (or Bacillus thuringiensis) |
Many types of caterpillars can attack tomato plants, including tomato budworms, fruitworms, and hornworms.
Signs include chewed leaves or holes in tomato fruits. You might also find tiny black dots on the plant — these are caterpillar droppings.
If the problem gets out of hand, your tomato plants might start losing plenty of leaves.
To get rid of caterpillars, pluck them off by hand and toss them into a bucket of soapy water.
For extra protection, try an organic spray with Bacillus thuringiensis (Bt), following the directions on the label.
Root knot nematodes
| SIGNS | Stunted growth Yellowing leaves Fewer tomato crops |
| TREATMENT | No treatment — rotate crops and plant resistant tomato varieties |
Root knot nematodes are microscopic, eel-like worms in the soil that can harm tomato roots!
They can prevent tomatoes from absorbing water and nutrients. This leads to stunted growth, yellowing leaves, and poor fruit set.
The plant will also look unhealthy and weak overall.
The best way to avoid root knot nematodes is to plant resistant varieties, like Improved Apollo.
Also, try growing French marigolds near your tomatoes, as they’re known to deter nematodes.
Sap-sucking pests
| SIGNS | Bugs on the underside of leaves Sticky coating on leaves |
| TREATMENT | Prune infested parts Use a neem oil solution weekly |
Sap-sucking pests can weaken tomato plants and even spread deadly viruses. Watch out for:
- Aphids: Tiny bugs that hide on the underside of leaves
- Spider mites: Leave whitish dots or fine webbing on leaves and stems
- Thrips: Attack leaves and can spread tomato spotted wilt virus
- Whiteflies: Small, moth-like insects that can carry plant diseases
To protect tomatoes from pests, set up stakes or a frame around your plants. Then drape a fine mesh over the area.
Also, check your tomato plants regularly, especially under the leaves. If you see any bugs, prune heavily infested parts.
Then, spray the remaining leaves with a mixture of ½ tbsp of neem oil + a few drops of dish soap + 1L of water. Do this weekly until the pests are gone.
Tomato Fruit Problems
Harvesting juicy, ripe fruit is the reward that every tomato grower looks forward to!
But when plants are stressed, the fruits can turn out misshapen or cracked.
Blossom end rot
| SIGNS | Dark, sunken patch on the bottom of the fruit |
| HOW TO PREVENT | Amend the soil with calcium sources |
Blossom end rot is a physiological disorder of tomato fruits.
Affected fruits develop a dark, sunken, leathery patch on the bottom part. The spot can grow and destroy the whole fruit.
It can be caused by:
- Incorrect soil pH
- Calcium deficiency
- Inconsistent watering
- Plant stress due to heat
To avoid blossom end rot, amend the soil with calcium sources like garden lime or gypsum. It’s best to do this a few months before the growing season.
Make sure to plant your tomatoes in a slightly neutral to acidic soil (6.2–6.8 pH level). You’ll need to lower the soil pH first if it’s too high.
Watering tomatoes consistently also helps them produce healthy fruit.
Catfacing
| SIGNS | Distorted fruit with irregular lobes and cracks |
| HOW TO PREVENT | Avoid high-nitrogen fertilisers during flowering and fruit set |
Catfacing is a common issue in tomato fruits, where they become misshapen, with irregular lobes and cracks.
It usually happens when the flower bud doesn’t form properly. It could be due to excessive nitrogen or cold temperatures during fruit set.
Heirloom tomatoes and those with large fruit are also more prone to catfacing.
To prevent this from happening, avoid high-nitrogen fertilisers once tomatoes start flowering.
Also, plant tomatoes at the right time of the year. That way, they don’t have to deal with chilly weather while producing fruit.
Cracking or splitting
| SIGNS | Visible cracks on the fruit |
| HOW TO PREVENT | Regular, consistent watering |
Tomato fruits can crack or split when there’s a sudden surge of soil moisture.
Inconsistent watering is often the cause, but sudden heat waves or intense sunlight can also be a factor.
Hot weather can dry out the soil fast, so some gardeners follow it up with heavy watering.
But when the plant suddenly absorbs more water than usual, the fruit swells too quickly and the skin can’t keep up — so it splits.
For prevention, water tomatoes regularly, especially once they start fruiting. In hot weather, mulching can keep the soil from drying too quickly.
Moreover, you can pick tomatoes before they ripen to save them from splitting on the vine.
Sunscald
| SIGNS | White, leathery patches on ripe fruit |
| HOW TO PREVENT | Regular, consistent watering |
Tomato fruits can suffer from sunscald when exposed to intense sunlight.
This can happen when the fruits aren’t shaded by foliage, often because of excessive pruning or leaf loss due to disease or pests.
The damage shows up as pale, sunken spots on the side of the fruit that’s most exposed to sunlight. The marks turn white or become leathery as the tomato ripens.
Luckily, sunscald doesn’t make tomatoes unsafe to eat. But the damaged parts might be tough or bitter.
To prevent it, avoid heavy pruning so the fruits stay partially covered by leaves. In extreme heat, provide some shade to protect your tomatoes.
Nutrient Deficiencies in Tomatoes
If tomatoes are grown in poor soil or not fertilised properly, they could suffer from nutrient deficiencies.
CALCIUM DEFICIENCY: A lack of calcium leads to blossom end rot. This shows up as a sunken, leathery patch on the bottom of the fruit.
MAGNESIUM DEFICIENCY: You might see yellowing between leaf veins. Lower leaves are affected first, then symptoms spread upwards.
NITROGEN DEFICIENCY: Leaves turn pale green or yellow, starting from the bottom and moving upwards. Plant growth is also stunted.
PHOSPHORUS DEFICIENCY: Leaves develop a purple or reddish tint, and stems may be thin. This is most common in young plants.
POTASSIUM DEFICIENCY: Leaf edges yellow and eventually dry out. Fruits may ripen unevenly or have yellow patches on the shoulders.
To avoid these issues, be sure to prepare the soil before growing tomatoes. Mix in compost or organic matter for a natural nutrient boost.
Young plants also benefit from slow-release, balanced NPK fertiliser.
Once tomatoes begin flowering, switch to a fertiliser that’s high in calcium, phosphorus, and potassium.
Tips to Prevent Tomato Problems
Make sure you’re growing tomatoes in the right conditions — healthy plants stand a better chance against diseases.
(Don’t hesitate to reach out to a local gardening specialist if you need help to prepare your garden bed for tomatoes!)
Before and after handling tomato plants, wash your hands for hygiene.
Also, disinfect your gardening tools, especially after using them on an infected plant.
Soak them in a solution of 1 part bleach and 9 parts water (or 70% rubbing alcohol) for a few minutes.
Finally, crop rotation is a must.
After growing tomatoes or other nightshades in a patch, wait 3–4 years before planting them again in the same spot.
Many pathogens that attack this plant group can linger in the soil. Rotating crops gives fungi, bacteria, and nematodes enough time to die off.
FAQs About Common Tomato Problems
Need more tips to keep your tomato plants healthy? Check out these Q&As!
How to get rid of soil-borne tomato diseases
Besides rotating your crops, you can also try soil solarisation. This method can help kill fungi, nematodes, and viruses that cause tomato diseases.
In summer (or the hottest part of the year), clear your garden bed. Take out all plant debris and weeds.
Next, water the soil thoroughly. Then cover the area with a clear plastic sheet that’s about 4–6mm thick.
Make sure the plastic is tightly secured in place, as you want to trap as much heat and moisture as possible.
Leave the plastic in place for 4–6 weeks to allow sunlight to sanitise the infected soil.
NOTE: Soil solarisation is not foolproof and only works on the top 15–30cm of the soil. It’s best to combine it with crop rotation to keep your garden healthy.
Why are my tomato flowers falling off?
Blossom drop in tomatoes is a sign of plant stress.
This can happen if the temperatures stay above 32°C or below 10°C for extended periods.
Moreover, if it’s too humid, flowers may not release pollen and end up dying off.
A nutrient imbalance might also be to blame. Too much nitrogen (and low phosphorus or potassium) can hinder flower development.
Here’s what to do to avoid blossom drop in tomatoes:
- Providing some shade if it gets too hot
- Proper spacing for good air circulation
- Using the right fertilisers for tomatoes
Do tomato plants die after fruiting?
Yes, tomato plants can die after fruiting, but it’s usually not due to their natural life cycle.
In colder regions, tomatoes can’t survive heavy frost. In tropical and subtropical areas, they might live longer, but they’re very vulnerable to disease.
That’s why most gardeners grow tomatoes as annuals!
