Why Do My Blackberries Have Brown Spots

Your blackberries have brown spots because of a fungal disease, most commonly anthracnose or botrytis, that attacks the fruit and canes.
 
If you’ve been asking yourself why your blackberries have brown spots, you’re not alone because this is one of the most common problems home gardeners face with blackberry plants.
 
These brown spots on blackberries usually show up as soft, tan or light brown lesions that can spread quickly and ruin your harvest if left untreated.
 
In this post, we’ll explore why your blackberries have brown spots, what causes those spots, and how to treat and prevent them.
 
Let’s dig in so you can enjoy clean, healthy berries again.
 

Why Your Blackberries Have Brown Spots

Your blackberries have brown spots because fungal pathogens have infected the fruit, and several different culprits can be responsible.
 
Here are the main reasons your blackberries have brown spots:
 

1. Anthracnose Fungus

Anthracnose is the number one reason your blackberries have brown spots.
 
This fungus, called Elsinoe veneta, thrives in wet, humid conditions and attacks both the canes and the fruit.
 
On the berries, it causes small brown spots that enlarge and turn grayish in the center.
 
If your blackberries have brown spots along with purple-edged lesions on the canes, anthracnose is likely the cause.
 

2. Botrytis Fruit Rot

Botrytis cinerea, also known as gray mold, is another reason your blackberries have brown spots.
 
This fungus causes soft brown spots on the berries that quickly turn fuzzy and gray.
 
Blackberries with brown spots from botrytis often appear during cool, rainy springs when flowers don’t dry out properly.
 
The spores land on blooms and stay dormant until the fruit starts ripening, which is when the brown spots appear.
 

3. Poor Air Circulation

When blackberry bushes are planted too close together, air can’t move through the canes.
 
This trapped moisture creates the perfect environment for the fungus that makes your blackberries have brown spots.
 
Without good airflow, dew and rain sit on the fruit longer, giving spores time to germinate.
 

4. Overhead Watering

Watering your blackberries from above keeps the foliage and fruit wet.
 
Wet berries are far more likely to develop brown spots because fungal spores need moisture to infect the fruit.
 
Switching to drip irrigation can dramatically reduce how often your blackberries have brown spots.
 

5. Overripe or Damaged Fruit

Blackberries that are overripe or nicked by insects are more prone to brown spots.
 
Once the skin is broken, fungi enter easily and cause those brown spots to form.
 
Pick your berries as soon as they’re ripe and handle them gently.
 

How to Treat Blackberries With Brown Spots

Once you notice your blackberries have brown spots, you need to act fast to save the rest of your crop.
 
Here’s how to treat blackberries with brown spots:
 

1. Remove and Destroy Infected Berries

Pick off every berry that has brown spots and throw it in the trash, not the compost.
 
Composting infected fruit can spread the fungal spores right back into your garden.
 

2. Prune Affected Canes

Cut out any canes with lesions or brown spots and dispose of them.
 
Thinning the canes improves airflow and reduces the humidity that helps fungi thrive.
 

3. Apply a Fungicide

If your blackberries have brown spots year after year, a copper-based or sulfur fungicide can help.
 
Spray according to label directions, starting when blooms appear and repeating as needed.
 

4. Water at the Base

Keep water off the leaves and fruit by watering at the soil level.
 
This single change often stops blackberries from getting brown spots in the first place.
 

Preventing Brown Spots on Blackberries

Prevention is the best way to keep your blackberries from getting brown spots again.
 
Here’s what to do:
 

1. Space Plants Properly

Give your blackberry plants enough room so air moves freely between them.
 
Good spacing keeps the fruit dry and makes it harder for fungi to take hold.
 

2. Mulch and Sanitize

Mulch around the base to stop spores from splashing up onto the fruit.
 
Clean up fallen leaves and old canes each fall to remove overwintering fungus.
 

3. Choose Resistant Varieties

Some blackberry varieties resist anthracnose and botrytis better than others.
 
Planting resistant types is a smart long-term way to avoid brown spots on your blackberries.
 

4. Harvest Often

Pick ripe berries every couple of days during harvest season.
 
Leaving overripe fruit on the canes invites the fungi that cause brown spots.
 

So, Why Do Your Blackberries Have Brown Spots?

Your blackberries have brown spots because of fungal diseases like anthracnose and botrytis, often made worse by wet conditions and poor airflow.
 
The good news is that treating and preventing brown spots on blackberries is totally doable with a few simple habits.
 
Remove infected fruit, prune your canes, water at the base, and give your plants room to breathe.
 
Do that, and you’ll spend far less time wondering why your blackberries have brown spots and more time enjoying a healthy, delicious harvest.