Bananas are delicious and nutritious, but what you may not know is they’re pretty easy to grow on Australia’s East Coast. But with ease come difficulties, and for banana trees, that comes in the form of pests and diseases. Left unchecked, you may end up with a disappointing yield come harvest.

So, what sort of pests and diseases plague banana trees? This guide will go through the most common of them, as well as provide solutions to improve the health of your banana trees.

Signs of a Healthy Banana Tree

Common Pests and Diseases in Banana Trees and How to Combat Them

Before you can tell whether or not your banana trees are in trouble, we first need to know what a healthy banana tree looks like. Here’s a quick list of signs that your banana tree is thriving.

  • Vibrant Green Leaves: One of the clearest signs of an undisturbed banana tree is lush, green foliage. The majority of the leaves should be long and, depending on the age of the tree, light to dark green. Older leaves may wither and die, but discoloration may be indicative of nutrient shortage or pest infestation.
  • Upright and Sturdy Pseudo-stem: Banana ‘trees’ are actually herbs with pseudo-stems, which are the plant’s main stalk. The pseudo-stem should be firm and stand upright without support structures. If it’s leaning to one side or tilts with minimal force, something may be going on in its root system. For simplicity’s sake, we’ll continue calling them banana trees (banana herbs doesn’t have a ring to it).
  • Consistent Growth: In just 9 months, you can expect a banana tree to grow to their full heights of 6 to 12 meters. There should be noticeable growth and an emergence of new leaves every so often. If not, this could be a sign that your banana isn’t receiving enough nutrients or sunlight.
  • Healthy Suckers: Suckers or pups are growths found around the base of a banana tree. They can be separated from the pseudo-stem and replanted to create a brand-new tree. Some trees can grow up to 20 pups during its lifetime. A lack of suckers or healthy ones may indicate the banana tree isn’t as healthy as you’d like.

Common Pests That Plague Banana Trees (and Suggested Solutions)

Equipped with the knowledge of what a healthy and unhealthy banana tree may look like, it’s time to figure out what pests can wreak havoc on your banana trees. The most commonly found pests in Australia include:

1. Aphids

Aphids are near-microscopic, sap-sucking insects that are usually black, but banana-targeting varieties may appear black in color. These insects may seek refuge and nourishment on the underside of banana leaves.

What aphids do is pierce the plants tissues with their needle-like mouths and suck on the sap. This causes the banana tree to become weak, stunting growth and wilting its leaves. In severe cases, the leaves may drop prematurely.

Symptoms of Aphid Infestation

  • Wilted leaves
  • Yellow leaves, particularly younger ones
  • Misshapen leaves
  • Aphid honeydew, which is a sticky residue, on leaves
  • Ants feasting on the aphid honeydew

Dealing with Aphid Infestations

  • Introduce ladybugs and lacewings into the environment. They are natural predators of aphids and do not target banana leaves. You can entice these aphid-eating insects by planting herbs like dill near your banana trees. A more hands-on approach involves blasting your banana trees with jets of water to dislodge and possibly end the lives on the infesting aphids.
  • If you want to try a more targeted approach, insecticidal soap can help. It’s made of common soaps like castile or vegetable-based dish soap. The fewer chemicals there are in the soap, the better. This soap can damage the cell membrane of soft-bodied insects, which causes them to dehydrate and shrivel.
  • Use a horticultural spray, which is derived from oils and petroleum sources. When applied correctly, the oil smothers the aphid, which causes it to suffocate and die. While chemical-based, it’s a lot less harsh compared to commercial chemical insecticides.

2. Banana Weevil

Common Pests and Diseases in Banana Trees and How to Combat Them

Banana weevils, aka banana root borers, are a common problem in Queensland and NSW. They are hard-shelled beetles use their sharp mandibles to bore into the pseudo-stem and rootstock of banana trees, where females lay eggs to cause more havoc in the future.

As you can imagine, holes in the pseudo-stem are not good for the banana tree’s health. This weakens the plant and prevents proper nutrient uptake. All this translates to a weakened plant, stunted growth, and possibly death in more serious infestations.

Symptoms of Banana Weevil Infestation

  • Wilted or yellow leaves
  • Weak or dying suckers on the plant’s base
  • Weakened pseudo-stem
  • Small holes on the pseudo-stem

Dealing with Banana Weevil Infestations

  • Introduce the banana weevil’s natural predators into the scene. One such candidate are parasitoid wasps, which target and kill weevils of all ages. You can attract them by planting nectar sources, such as Grevillea.
  • If the wasps aren’t doing the job, an insecticide may do the trick. Opt for organic-based insecticides whenever possible to prevent damage to your banana trees and surrounding plants. If you need to use a harsh chemical, follow the instructions on the container closely.

3. Scale Insects

Scale insects are similar to aphids in how they feed on banana trees. Some are soft-bodied, while others are hard, but both varieties are found in Australia. After molting, scale insects may lose the ability to move, making them easier to spot.

Like aphids, scale insects feed on the sap of banana trees by piercing leaves and the pseudo-stem. The longer they feed, the weaker the plant becomes. This ultimately prevents the tree from developing its fruit properly.

Symptoms of Scale Insect Infestation

  • Wilting or yellowing leaves
  • Sticky residue known as honeydew
  • Presence of ants, which are attracted to the honeydew

Black, powdery mold growth on the leaves and fruit

Dealing with Scale Insect Infestations

  • Invite ladybugs and lacewings to your garden since they feast no aphids and scale insects. Parasitic wasps, which combat banana weevils, are also a worthy candidate.
  • An insecticidal spray or horticultural oil spray can eliminate more serious infestations effectively. Make sure to choose the appropriate spray based on the type of scale insect in your garden.

4. Caterpillars

Moths and butterflies may be cute, but when they’re still caterpillars, they’re a nuisance to deal with. Various caterpillar species in Australia feast on banana leaves, like banana skipper larvae and Sphingid moth larvae.

The main concern with caterpillar infestations is how they treat the leaves. Some species munch on them, but others roll the leave up to build a makeshift shelter as they feed. Their droppings, known as frass, can cause trouble by blocking sunlight.

Symptoms of Caterpillar Infestation

  • Hole in the leaves
  • Ragged leaves
  • Missing leaves
  • Presence of frass

Dealing with Caterpillar Infestations

  • Try summoning a flock of birds to your garden by planting sweet osmanthus or an ivory curl flower tree. However, some birds are also pests, such as the common starling. If you’re worried about birds pecking holes into other fruit trees, ladybugs and lacewings are your best caterpillar-controlling options.
  • An insecticide containing Bacillus thuringiensis is an effective method for targeted control. This chemical ends the lives of caterpillars while also leaving beneficial insects unharmed. Make sure to follow the instructions on the label.

5. Nematodes

Nematodes or roundworms are worm-like creatures that seek refuge in the ground, including in Australia. Many species of nematodes are beneficial, but a select group can be invasive and harm banana trees.

These creatures damage banana trees by feeding on root tissues, which can prevent the tree from growing properly. If left unchecked, the root system may fail entirely, and the banana tree will topple over.

Symptoms of Nematode Infestation

  • Stunted growth
  • Wilting leaves
  • Yellow leaves
  • Poor fruit production
  • Dead or brown patches on the banana tree’s roots

Dealing with Nematodes

  • You may have inadvertently introduced nematodes in your garden by using infested planting material. The next time you want to plant something, source the materials from a source that’s free from harmful nematodes. You can also try rotating crops or tilling the soil to minimize nematode populations in the area.
  • Make amends to the nematode-infested soil in your garden by introducing organic compounds like manure or neem cake. These compounds are filled microorganisms that compete with nematodes for sustenance in the soil. If successful, they’ll drive down the nematode population, leaving nothing but healthy soil for your next banana tree.
  • While ladybugs and lacewings may not help control nematode populations, other nematode species can. It may take longer for the predatory nematodes to devour the plant-parasitic ones.

Fungal and Viral Diseases That Can Harm Your Banana Trees (and Common Solutions)

Common Pests and Diseases in Banana Trees and How to Combat Them

Beyond munching menaces and sap-sucking scoundrels, banana trees also receive threats from the microscopic world. Fungi and viruses can invade the inner workings of a banana tree, which can lead to all sorts of issue down the road.

1. Banana Bunchy Top Virus (BBTV)

BBTV is virus that cripples banana trees. It’s among one of the most devastating viruses on the planet, which has caused massive losses globally, including Australia. We have banana aphids to thank for spreading this highly contagious virus, which disrupts phloem transport and other vital functions.

Symptoms of BBTV

  • Stunted growth
  • Bunch malformation
  • Discolored or weak leaves

Dealing with BBTV

Alas, there’s nothing we can do stop BBTV in its tracks. However, there are preventive measures you can employ, such as removing infected plants from the area and managing aphid populations.

2. Panama Disease

Panama disease is caused by a fungus that lurks in the soil before striking banana tree roots. When the fungus takes hold of the roots, it disrupts water and nutrient intake, leading to a series of symptoms that makes the tree look sad and perform poorly. Despite its name, Panama disease is found worldwide, including in our backyards in Australia.

Symptoms of Panama Disease

  • Wilted leaves
  • Yellow leaves
  • Stunted growth
  • Split pseudo-stem
  • Discolored vascular tissue inside the pseudo-stem

Dealing with Panama Disease

  • You can try rotating crops—i.e., growing different types of crops in the same area over a sequence of seasons. Aim for growing non-susceptible crops like legumes and marigold. By removing the fungus’ source of food temporarily, it cannot thrive and will possibly die out.
  • More serious cases may require soil fumigation, which is when gaseous chemicals are introduced to the soil to kill or suppress fungi. The fumigation gas should contain methyl bromide or metam sodium for the best results.

3. Sigatoka Disease

Sigatoka Disease is a complex of fungal foes caused by Mycosphaerella spp. that attack banana leaves. Infected banana trees will spread the fungus via rain and wind, ultimately preventing proper fruiting potential. There are several strains of this disease, with Black Sigatoka being the most aggressive.

Symptoms of Sigatoka Disease

  • Brown or gray spots on leaves
  • Dark streaks connective the leaf spots
  • Yellow leaves
  • Premature ripening, leading to reduced yield and quality
  • Leaf death

Dealing with Sigatoka Disease

Like BBTV, there’s very little you can do to eliminate Sigatoka Disease. Your best options are preventive measures, which includes monitoring your garden for symptoms and removing infected plants. That said, you can also try planting banana varieties that are less susceptible to Black Sigatoka, like Goldfinger and certain plantain varieties.

4. Banana Bract Mosaic Virus (BBrMV)

BBrMV lurks in the sap of banana trees. The pathogen is a part of the Potyviridae family and disrupts the tree’s internal processes, ultimately leading to poor fruit quality. This virus is spread in 2 ways: via contact with infected aphids and using contaminated planting materials.

Symptoms of BBrMV

  • Discolored bracts
  • Distorted leaves
  • Stunted growth
  • Bunch deformities
  • Reddish streaks on the leaf stalks or pseudo-stem

Dealing with BBrMV

Like other diseases and viruses on this list, BBrMV has no cure. You can only prevent the spread by destroying infected aphids, using planting materials free of the virus, and destroying infected trees.