Grey Mould (Botrytis): How to Identify, Treat & Prevent It in Australian Gardens

Found fuzzy grey mould spreading across your strawberries, tomatoes, roses or flowers?

There’s a fair chance you’re dealing with grey mould, commonly called Botrytis or Botrytis blight.

The fungus most commonly associated with the problem is Botrytis cinerea, and once conditions suit it, things can go downhill fairly quickly. Flowers brown off. Fruit turns soft. Leaves develop dead patches. Then that unmistakable dusty grey growth appears over damaged plant tissue.

The good news?

Botrytis is much easier to manage when you catch it early.

And spraying alone usually isn’t the whole answer.

To get grey mould under control, you need to:

1. Remove the main sources of infection.
2. Help foliage and flowers dry faster.
3. Reduce the conditions that favour Botrytis.
4. Protect healthy growth where appropriate.
5. Keep checking for fresh infection.

Here’s how to do exactly that.

Table of Contents

• Grey Mould at a Glance
• What Is Grey Mould?
• What Does Botrytis Look Like?
• Botrytis on Different Garden Plants
• Is It Definitely Grey Mould?
• What Causes Grey Mould?
• How Botrytis Spreads
• How to Treat Grey Mould on Plants
• Can Neem Oil Treat Botrytis?
• A Simple Botrytis Action Plan
• How to Prevent Grey Mould Coming Back
• Grey Mould in Australian Conditions
• Common Grey Mould Treatment Mistakes
• Grey Mould FAQs
• The Bottom Line
• Next Reads for Managing Mould and Fungal Disease

If you already know you’re dealing with Botrytis, these are the two tools that make the treatment steps below easier:

Grey Mould at a Glance

If you already know you have a fungal problem and want to compare treatment options, have a look at our guide to organic fungicides in Australia.

What Is Grey Mould?

Grey mould is a fungal plant disease most commonly associated with Botrytis cinerea.

You may also see it described as:

• Botrytis
• Botrytis blight
• Botrytis grey mould
• Gray mold, particularly in American gardening information

Different name, same basic gardening headache.

Botrytis can affect a huge range of plants and plant parts. Flowers, fruit, leaves, stems and seedlings can all be affected.

One of the important things to understand is that Botrytis loves opportunity.

Old flowers, damaged leaves, bruised fruit, pruning wounds and dying plant material can give it an easier place to establish. When the surrounding conditions stay damp and humid, infection pressure can increase further.

That is why grey mould control isn't simply about finding something to spray.

You're trying to break the Botrytis cycle.

What Does Botrytis Look Like?

The classic symptom is a fuzzy or dusty grey-brown mould growing across affected plant tissue.

But don't wait for your plant to look like it has grown a grey beard.

Earlier symptoms may include:

• Soft or water-soaked-looking areas
• Brown spots or patches on flowers and leaves
• Flowers turning brown before opening properly
• Soft, rotting areas on fruit
• Browning around damaged stems
• Buds failing or collapsing
• Wilt or dieback around infected tissue
• Seedlings collapsing
• Dead plant material becoming covered in grey spores

Once the fungus begins producing large amounts of spores, the surface can develop the grey, dusty appearance that gives the disease its common name.

If you bump a badly infected flower or fruit and see what looks like a little cloud of grey dust, you're looking at a serious amount of spore production.

That plant needs attention.

Botrytis on Different Garden Plants

Grey mould doesn't always look exactly the same on every plant.

Here's what to watch for on some common garden favourites.

Grey Mould on Strawberries

Strawberries are a classic target.

You may first notice a brown or soft patch developing on the fruit. The berry can then become increasingly soft before grey fuzzy growth develops over the surface.

Crowded plants, old fruit, dead leaves and wet conditions can all make life easier for the fungus.

Remove infected berries rather than leaving them hanging around underneath healthy fruit.

Botrytis on Tomatoes

On tomatoes, keep an eye out for:

• Soft rotting fruit
• Grey mould around damaged areas
• Brown patches on stems
• Infection around pruning or leaf-removal wounds
• Dying flowers or plant debris becoming mouldy

Dense tomato plants can create their own humid little jungle, particularly when foliage stays packed together.

Pruning for sensible airflow can help, but don't go berserk and strip the plant bare.

Botrytis on Roses

On roses, grey mould can attack petals and flower buds.

You may notice:

• Brown spotting on petals
• Flowers becoming discoloured
• Buds failing to open properly
• Petals sticking together
• Grey fungal growth developing on old or damaged blooms

Spent flowers are worth removing regularly during disease-prone weather instead of letting them rot on the plant.

Botrytis on Grapes

Botrytis can affect grape flowers and berries, particularly where bunches stay damp and airflow is poor.

Watch for softening berries, browning and later grey fungal growth.

Dense canopies that remain humid for long periods create conditions that deserve extra attention.

Grey Mould on Lettuce and Leafy Greens

Look around the lower leaves and crown for:

• Soft brown tissue
• Collapsing leaves
• Grey mould developing over dead or damaged areas

Crowding and constantly damp lower foliage can make these problems harder to manage.

Botrytis on Flowers and Ornamentals

Flowers are particularly vulnerable because petals naturally age and die.

Old blooms can become an easy foothold for Botrytis, especially during damp weather.

Regular deadheading isn't just about keeping things looking tidy—it removes plant material the fungus may otherwise colonise.

Is It Definitely Grey Mould?

Before you reach for a treatment, make sure you're dealing with the right problem.

Not every white or grey mark on a plant is Botrytis.

Grey Mould vs Powdery Mildew

These two get mixed up all the time.

Grey mould:

• Often develops on damaged, soft or dying tissue
• Commonly looks grey-brown and fuzzy
• Fruit and flowers may become soft or rotten
• Moist, humid conditions are a major factor

Powdery mildew:

• Usually looks like white flour or powder sitting on leaves
• Often spreads as patches across otherwise intact foliage
• Doesn't normally begin as soft fruit rot
• Has a noticeably different powdery appearance

If your plant looks like it has been dusted with flour, read our full guide on how to get rid of powdery mildew.

Grey Mould vs Ordinary Rot

Rotting fruit does not automatically mean Botrytis.

Physical damage, excess moisture, other fungi and bacteria can all cause fruit to collapse.

The characteristic fuzzy grey spore growth makes Botrytis more likely, but diagnose the whole pattern rather than one brown spot.

Grey Mould vs Root Problems

If an entire plant is wilting but there's no obvious mould on above-ground tissue, investigate the roots and watering conditions too.

Botrytis is only one possible cause of a struggling plant.

Rule of thumb: diagnose first, treat second.

What Causes Grey Mould?

Think of a Botrytis outbreak as three things meeting at the wrong time:

fungal spores + vulnerable plant tissue + favourable conditions

Spores are only part of the story.

Your garden's environment determines whether they get the opportunity to become a much bigger problem.

1. High Humidity

Dense foliage and enclosed growing areas can trap moisture around leaves and flowers.

That creates a sheltered microclimate where plant surfaces dry slowly.

2. Wet Foliage and Flowers

Rain, overhead watering and condensation can all keep plant tissue damp.

The longer delicate flowers and damaged tissue stay wet, the more opportunity disease has to establish.

3. Poor Airflow

Crowded foliage dries slowly.

This is why Botrytis can become troublesome in:

• Packed greenhouses
• Dense tomato plants
• Closely spaced pots
• Protected balconies
• Grow tents with weak air movement
• Overgrown flower beds

4. Dead and Dying Plant Material

Old flowers, dead leaves and rotting fruit shouldn't be allowed to pile up around an active outbreak.

Botrytis can colonise unhealthy plant material and produce more spores from it.

5. Plant Damage

Bruised fruit, broken stems and pruning wounds can create vulnerable points.

Handle plants gently when conditions are highly favourable for disease.

6. Soft, Crowded Growth

Plants pushed into excessive leafy growth can develop dense canopies with poorer airflow.

The goal isn't to starve the plant.

It's simply another reason to avoid the “more fertiliser must always be better” approach.

How Botrytis Spreads

Understanding the mechanism makes prevention a lot less mysterious.

A simplified Botrytis cycle looks like this:

1. The fungus survives on infected or dead plant material.

↓

2. Spores are produced when conditions suit it.

↓

3. Spores reach susceptible plant tissue.

↓

4. Prolonged moisture and humidity help infection establish.

↓

5. Infected tissue deteriorates.

↓

6. More grey spores develop and spread.

And around we go again.

That's why removing a mouldy strawberry but leaving a pile of infected leaves underneath the plant doesn't properly solve the problem.

You need to reduce the source, the spread and the conditions helping it along.

How to Treat Grey Mould on Plants

If you've found an active Botrytis outbreak, here's the order I'd tackle it.

Step 1: Remove the Worst Infected Material

Start with obviously infected:

• Fruit
• Flowers
• Leaves
• Stems
• Fallen debris

Handle infected material gently rather than shaking spores everywhere.

Bag badly infected material as you go.

Don't drag mouldy foliage across healthy plants on the way out of the garden.

Step 2: Clean Your Tools

If you've been pruning infected tissue, clean your secateurs before moving to another plant.

This is especially important when cutting around diseased stems or damaged tissue.

Garden hygiene isn't glamorous, but neither is moving a disease problem from plant to plant with the same pair of snips.

Step 3: Open Up the Plant

You want foliage to dry faster.

That may mean:

• Removing unnecessary dead growth
• Lightly thinning extremely congested foliage
• Moving pots further apart
• Improving greenhouse ventilation
• Increasing air movement indoors
• Training vines and tomatoes more openly

Don't turn “improve airflow” into “remove half the plant”.

You want enough foliage for healthy growth, just without creating a damp cave in the middle.

Step 4: Change How You Water

Try to water the root zone rather than showering foliage and flowers unnecessarily.

Morning watering is usually handy because any accidentally wet foliage has more time to dry during the day.

Our Australian garden watering guide goes deeper into watering at the roots, morning timing and avoiding constantly wet foliage.

Step 5: Protect the Remaining Healthy Growth

Once badly affected material has been removed and the growing conditions are being corrected, an appropriate plant protectant can form part of the management plan.

For growers wanting a ready-made option, PureCrop1 Plant Protectant is the product we currently pair with improved airflow in our Botrytis management recommendations.

PureCrop1 is a plant-based product used as a fungicide, insecticide and biostimulant/plant protectant.

For Botrytis, the important point is this:

Don't use a spray as an excuse to ignore the environment.

If your plants remain packed together, covered in dead flowers and wet every evening, you're fighting the disease with one hand while helping it with the other.

Always follow the current product directions for mixing, application frequency and plant suitability.

Step 6: Recheck the Plant

Old damage won't magically turn green again.

What you're looking for is whether fresh infection is continuing.

Check:

• New flowers
• New leaves
• Developing fruit
• Recently pruned areas
• Dense interior foliage

If clean new growth stays clean, you're heading in the right direction.

Can Neem Oil Treat Botrytis?

Neem gets recommended for just about every garden problem on the internet, which is exactly why it's worth being precise.

Our Neem + Karanj Oil is best thought of as a plant-care oil used as part of a preventative maintenance routine where label directions allow.

For an established Botrytis outbreak, I would not make neem your entire strategy.

The priority is still:

remove infection → increase airflow → reduce leaf wetness → use a suitable treatment where required → monitor

Oil sprays can also stress foliage if used in hot conditions or on sensitive plants, so always test first and follow the current label directions.

In other words: neem can have a place in a broader garden-care program, but don't expect one oily spray to fix a Botrytis-friendly environment.

A Simple Botrytis Action Plan

If you want the short version, here it is.

Today

• Inspect the entire plant.
• Remove badly infected fruit, flowers and foliage.
• Bag diseased material.
• Clean pruning tools.
• Clear dead debris from around the plant.
• Increase spacing or airflow.
• Avoid wetting foliage unnecessarily.
• Apply an appropriate treatment if needed and permitted by its directions.

Over the Next Few Days

Check clean growth for:

• Fresh brown lesions
• Soft fruit
• Collapsing flowers
• New grey fuzzy growth

Don't judge progress by old scars.

Judge it by whether new infection is appearing.

During the Following Weeks

Keep pressure low by maintaining:

• Better airflow
• Cleaner garden beds
• Sensible plant spacing
• Root-zone watering
• Regular removal of dead flowers and fruit
• Routine inspections after damp weather
• Consistency beats panic spraying.

How to Prevent Grey Mould Coming Back

Preventing Botrytis is mostly about making your garden a lousy place for it to multiply.

Give Plants Breathing Room

Avoid cramming every plant together.

More plants don't automatically mean a bigger harvest if the canopy becomes a damp wall of foliage.

Good spacing helps air move through.

Water the Soil, Not the Whole Plant

Use:

• Drip irrigation
• A watering wand
• Direct root-zone watering

where practical.

If you do wet foliage, earlier in the day gives it a better chance of drying.

Deadhead Regularly

Old flowers are perfect material to remove before they become fungal real estate.

This is particularly worthwhile on:

• Roses
• Pelargoniums
• Chrysanthemums
• Dense flowering annuals
• Greenhouse ornamentals

Pick Ripe and Damaged Fruit

Don't leave split tomatoes, damaged strawberries or rotten fruit sitting around.

Remove them before the fungi throw a party.

Remove Dead Leaves

Pay attention underneath plants.

The canopy can look spotless while last month's wet leaves are decomposing underneath it.

Ventilate Greenhouses and Grow Areas

Growing under cover helps control the environment—but it can also trap humidity.

Use ventilation and air movement to prevent long periods of stagnant, humid air.

Keep Plants Healthy Without Overdoing It

Healthy plants generally handle stress better, but excessively lush, dense growth can make airflow problems worse.

Feed for balanced growth rather than simply chasing the greenest possible canopy.

Grey Mould in Australian Conditions

Australia isn't one climate.

A gardener in humid coastal Queensland deals with completely different conditions from someone growing in inland Victoria.

So rather than saying “Botrytis season starts in month X”, watch the conditions in your own garden.

Humid and Subtropical Gardens

Pay extra attention to:

• Canopy density
• Airflow
• Long humid periods
• Wet flowers and fruit
• Crowded undercover areas

Frequent inspection is worth the effort because disease pressure can build quickly when plants stay humid.

Temperate Coastal Gardens

Periods of cool, wet weather can make flowers, strawberries, tomatoes and dense ornamentals particularly worth checking.

Don't wait until the whole plant is grey.

Check after runs of wet weather.

Cool and Protected Growing Areas

Greenhouses can remain humid even when the outside weather doesn't feel particularly muggy.

Condensation is the giveaway.

If water is regularly forming on greenhouse surfaces and plants remain damp, improve ventilation.

Indoor Gardens and Grow Tents

Indoor growers have one huge advantage:

you control the environment.

Use it.

Air circulation, extraction, sensible plant spacing and humidity management can be just as important as whatever goes into the spray bottle.

Common Grey Mould Treatment Mistakes

Mistake 1: Spraying Without Removing Infection

A spray doesn't make a rotten strawberry healthy again.

Remove the worst disease first.

Mistake 2: Keeping Plants Constantly Wet

If leaves and flowers stay wet for long periods, you're maintaining the conditions that encouraged the problem.

Mistake 3: Leaving Dead Flowers Everywhere

Spent blooms aren't harmless during disease pressure.

Clean them up.

Mistake 4: Overcrowding

Packing more plants into a small area often means slower drying and poorer airflow.

Mistake 5: Assuming Every Fungal Disease Is the Same

Powdery mildew, Botrytis, rust and various rots do not behave identically.

Identify the problem before building the treatment program.

Mistake 6: Mixing Garden Sprays at Random

Natural doesn't mean impossible to damage plants with.

Some oils, sulphur products and other sprays should not be casually stacked together.

Follow labels and product-specific instructions.

For a broader comparison, see our organic fungicide guide.

Grey Mould FAQs

Is Botrytis the same as grey mould?

Grey mould is a common name for disease most frequently associated with fungi in the Botrytis genus, especially Botrytis cinerea. You may also hear the disease called Botrytis blight.

Is grey mould the same as powdery mildew?

No.

Powdery mildew generally produces a white, powder-like coating across leaves and stems.

Grey mould more commonly develops as grey-brown fuzzy growth on soft, dying or infected tissue and is often associated with rot in fruit and flowers.

Can plants recover from Botrytis?

Yes, depending on the severity of the infection and the part of the plant affected.

Damaged tissue will not repair itself, so the goal is to remove badly affected material and protect healthy growth from further infection.

Should I remove the whole plant?

Not necessarily.

A small localised infection may be manageable by removing affected plant material and correcting the environment.

If the plant is extensively rotted, collapsing or repeatedly producing heavily infected material, removing it may be the cleaner option.

Does Botrytis live in soil?

Botrytis can persist on infected plant debris and resistant structures associated with previous disease.

That's one reason good garden hygiene matters.

Rather than obsessing over “sterilising the soil”, focus on removing infected debris and correcting the conditions that allow repeated outbreaks.

Can grey mould spread between plants?

Yes.

Spores can move onto other susceptible plant material, so heavily infected plants should be handled carefully.

Spacing, sanitation and airflow help reduce the chances of a localised infection becoming a bigger garden problem.

Should I compost Botrytis-infected material?

During an active outbreak, the simplest low-risk backyard approach is to bag and dispose of heavily infected material rather than putting it straight into your normal compost pile.

A poorly managed compost heap may not reach conditions suitable for reliably destroying every plant pathogen.

Does neem oil kill Botrytis?

Neem and other plant oils may be used in preventative plant-care programs, but they should not be treated as a magic cure for an established grey mould outbreak.

For active Botrytis, prioritise sanitation, airflow, moisture management and an appropriately chosen treatment.

Does PureCrop1 work for Botrytis?

PureCrop1 is currently part of our recommended approach for Botrytis alongside increased airflow.

The best results come from treating it as one part of an integrated strategy—not using it while leaving infected debris, overcrowding and wet foliage untouched.

You can see the current product and directions here: PureCrop1 Plant Protectant.

Why does Botrytis keep coming back?

If grey mould repeatedly returns, look beyond the spray bottle.

Check whether:

• Plants are too crowded
• Dead flowers are being left behind
• Foliage stays wet overnight
• Humidity remains high
• Air movement is poor
• Rotten fruit is left on or under plants
• The same heavily infected debris remains nearby

Recurring disease usually means something in the growing environment is still favouring it.

The Bottom Line

Grey mould can look nasty, but the control strategy is pretty logical once you understand how Botrytis works.

Remove what is infected.
Keep the plant cleaner.
Help everything dry faster.
Improve airflow.
Water intelligently.
Protect healthy growth where appropriate.
Then keep checking.

That's a much stronger approach than hammering a wet, overcrowded plant with spray after spray and wondering why the mould keeps coming back.

If you're dealing with Botrytis right now, start by cleaning up the infected material and opening up airflow.

Then, if you need additional plant protection, take a look at:

• PureCrop1 Plant Protectant
• Neem + Karanj Oil for preventative plant-care routines where appropriate
• Organic Pest Control Solutions
• Best Organic Fungicides in Australia

And if the “mould” on your plant is actually a white flour-like coating rather than fuzzy grey rot, jump across to our Australian powdery mildew guide.

Catch it early, fix the conditions that caused it, and you'll give the healthy parts of your garden a much better shot.

Happy growing!

Next Reads for Managing Mould and Fungal Disease

Still seeing fuzzy growth, spots or recurring disease in damp conditions? These guides will help you compare common fungal problems and make your garden less favourable to repeat outbreaks.

• How to Get Rid of Powdery Mildew in Australia
• Best Organic Fungicide Australia Guide
• How to Correctly Water Your Garden
• Pest Control IPM Stack: Top 10 Organic Solutions

About the Author