Petunias can make your patio or deck a little more merry with their vibrant colors and heavenly fragrances.
Although these flowers are easy to grow, they’re susceptible to some pests and diseases.
All aphids, tobacco budworms, thrips, and rose slugs can affect your beautiful petunias, but don’t fret! Controlling these pests and diseases is easy.
In today’s article, I’ll help you identify and manage common petunia pests and diseases to keep your lovely flowers healthy and happy.
Let’s jump into the details.
It can be frustrating to see your beloved petunia struggling with pest infestations.
However, by learning how to identify and get rid of common pests, you can keep your plant as lovely as ever.
Let’s check out some of the common petunia pests.
Aphids are pear-shaped, tiny insects that, in some cases, can be nearly invisible to the naked eye.
Adult aphids don’t usually grow bigger than ¼ inches. Various species of this insect come in different colors, including brown, white, black, gray, green, and yellow.
These insects are most active during the peak of the summer, but this doesn’t mean they’re inactive in cold weather. They’re resilient to low temperatures.
Identifying aphids can be challenging due to their small size. Yet, you can tell when these insects make a home out of your flowers by the damage they leave behind.
Here are some signs of aphid damage:
- White flakes: Aphids shed their exoskeletons frequently, leaving behind small white flakes on your plant.
- Curling of the leaves: Some aphids inject their toxins into your petunia leaves, causing them to curl.
- Yellow leaves: Petunia leaves can turn yellow when insects feed on them.
- Honeydew: You can spot sticky and shiny substances on the leaves of the plant.
- Black spots: After a while, sooty mold fungi can grow on the honeydew.
Aphid damage is rarely severe enough to be the end of your plant. Still, the earlier you act after spotting any of the previous signs, the better it’ll be for your plant.
The easiest and quickest way to get rid of these annoying insects is by using a strong stream of water from a garden hose. The water will knock off the aphids, as well as the larvae.
You can repeat this process every couple of days until there are no insects on your plant. If that doesn’t work, you’ll need to make a homemade spray of liquid soap and water.
Then, apply this mixture directly to the infected parts of your plant.
The last resort would be using a suitable insecticidal soap spray.
The tobacco budworm is a caterpillar of the moth of the same name that loves petunias. It’s common in the southwestern and eastern parts of the U.S.
The caterpillars are usually brown, red, green, or even purple. You can identify them by the white stripes that run along their abdomens.
What’s unique about these insects is that they have erect hairs on their bodies that look like spikes.
Unfortunately, tobacco budworms can feed on all parts of your petunias. You’ll notice irregular-shaped holes all over your plant.
They’re likely to disfigure flowers in the bud stage, feeding on them from the inside out.
Another sign of a tobacco budworm infestation is the presence of tiny black specks about the size of a pinhead. These specks are the frass of the caterpillars.
Tobacco budworms can be around 1 ¾ inches in length, making them easy to spot.
So, grab a bucket and put on gloves, as you’ll be removing these insects by hand. Additionally, make sure to remove damaged parts of your plant to encourage regrowth.
Using insecticides isn’t the best option in this case. Broad-spectrum insecticides rarely get rid of caterpillars, not to mention how they’ll affect beneficial insects, like bees.
If you’re facing an ongoing issue with tobacco budworms, you can use a soil drench that includes beneficial nematodes.
Thrips, also known as thunderflies and thysanoptera, are super thin insects that love to dine on petunias.
These insects can be as thin as a sewing needle, making them hard to spot.
They suck on plants, causing a lot of damage. What’s worse is that they can transmit viruses to your petunias.
Nymphs are tiny, thin, and almost translucent, so you can’t easily identify them.
On the other hand, you can recognize adult thrips by their slender bodies and fringed wings.
These insects can be brown, yellow, or, in some cases, black.
Furthermore, they leave behind stippling and discolored flecking. You might also spot striking color breaks in the flowers.
Although thrips don’t cause serious damage to your petunias, they can act as vectors, passing viruses from one plant to another.
So, you have to get rid of any thrips and make sure they won’t be hiding somewhere around your plant.
Here are some essential tips to help you manage the situation:
- Prune the infested parts and spray the petunia with water to dislodge the thrips. It’s essential to spray the undersides of the leaves, as they love to hide there.
- Use an insecticidal soap and sprinkle some diatomaceous earth on your flowers.
- Remove weeds and grass to eliminate any alternate hosts for the insects.
Rose slugs are insects that look like crossovers between caterpillars and slugs. These insects are the larvae of sawflies.
The damage they cause is rarely life-threatening to your petunias. Yet, they can make your lovely flowers weak and unsightly.
Rose slugs look similar to caterpillars, with a body length of around ½ to ¾ inches when fully grown. They tend to have a smooth, greenish-yellow body and a brown head.
Rose slugs usually feed on the leaves, leaving a translucent layer of leaf tissue behind.
These insects tend to feed on the underside of the leaves. However, they might feed on the upper surface when the plant is shaded.
Generally, rose slugs don’t make holes in the plant. Instead, they graze away the surface until the epidermis layer is the only thing remaining.
Then, the affected area dries up and turns brown or white.
You can easily manage the situation by picking any visible rose slugs off the plant. You can also wash them off the stems and foliage using a strong jet of water from your garden hose.
However, you’ll still need to pick them up when they fall off the plant and get rid of them away from your petunias.
If the infestations are recurring, you can control the situation with a proper pesticide.
Petunias are resilient and easy to grow. They can tolerate neglect and tough conditions, but they’re still prone to some diseases.
Unfortunately, some of these diseases can become life-threatening if not treated early. So, let’s check out some common petunia diseases and how to identify them.
Powdery mildew is a fungal disease that can diminish the beauty of your petunia.
It all starts when the wind carries spores to your petunia. In no time, these fungi will start taking over your delicate plant.
Not only that, but they’ll also spread to other plants in your garden.
Powdery mildew is easy to identify; your plant will look like it has been dusted with flour.
This white powder typically covers the upper part of the leaves, but you may find it on the underside as well.
You might notice that the leaves and buds are starting to twist, break, or become disfigured.
The first thing you need to do is remove and dispose of any affected parts of the plant. This will keep the spread of the disease to a minimum.
Then, find a suitable fungicide for powdery mildew. The fungicide will get rid of the mildew and protect the other parts of the petunia that aren’t infected.
Root, stem, and crown rot can affect your beloved petunia, mainly due to overwatering. They can also occur when the pots don’t have proper drainage.
Sadly, these diseases can be life-threatening, especially root rot. Therefore, you need to act quickly!
Infected petunias typically have stunted growth and discoloration. You might find that the soil is wet and smells weird.
In the case of root rot, the roots will look reddish-brown and mushy, instead of their healthy white color.
To stop the disease from spreading, you’ll need to remove all the infected parts. Additionally, you’ll have to wash all the soil off the roots and get rid of it.
Then, you’ll need to sanitize the pot and wash it thoroughly. After that, repot your plant in new, well-draining soil.
White spots may be a sign of powdery mildew. This disease appears as tiny white spots on the top of petunia leaves.
To treat this disease, you’ll need to remove any affected parts of your plant and use a suitable fungicide.
In the late stages of powdery mildew, your plant might start looking white due to the high number of spores on the leaves. Moreover, a white petunia might be a sign of mold growth.
Overwatering is the main cause of root rot, which can be the end of your lovely petunia. Ideally, you only want to water your plant when the first two inches of the soil feel dry to the touch.
In addition, make sure the soil isn’t too heavy. You should also pick a pot with proper drainage.
Yes! Petunias seem like a delicious meal for many animals, including rabbits, chipmunks, chickens, and squirrels.
Despite being tough plants, petunias are susceptible to pest infestations. For example, aphids, thrips, rose slugs, and tobacco budworms love feeding on your plant.
Your petunias are also prone to diseases like powdery mildew and root rot.
In all cases, if you spot any alarming signs, it’s best to act as quickly as possible to stop any further damage to your plants.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.