How To Know What’s Eating Your Asparagus Roots

Do you suspect something is eating at your asparagus roots but can’t quite put your finger on what it is? It can be frustrating fighting against an invisible enemy. It’s crucial to find the culprit to know how to deal with it accordingly. 

To know what’s eating your asparagus roots, examine your plant for signs of pests. They’re often responsible for damaged roots. Infections caused by fungi and other pathogens are also likely responsible. Another possible reason for roots that appear eaten up is overwatering, resulting in decay.

In this article, you’ll learn how to identify and fix problems with your asparagus roots and help nurture the plant back to full health. I’ll give you practical, step-by-step instructions – keep reading if that interests you. 

1. Start by Looking for Pests

If you feel that your asparagus roots are being eaten, it makes the most sense to start by checking for pests.  A pest infestation is the most likely case if your asparagus roots aren’t rotting but seem to be damaged physically. 

The tiny pests that typically infest asparagus plants can chew away at roots without you ever noticing. Some can only be found below the soil, making identification somewhat challenging. 

The Signs of a Pest Infestation

Other than the damaged roots, there are some other symptoms that asparagus plants under attack by pests will often display. Knowing these signs can help you identify hidden dangers sooner and more accurately. It’s crucial to recognize these signs early on for your asparagus bed’s long-term health. 

  • Small but noticeable lesions on the asparagus stems (spears and ferns) indicate a pest infestation. 
  • Damaged ferns. When a pest problem gets severe enough, the holes and eaten chunks of leaves will be very apparent. 
  • Significant premature foliage death. (Ferns that die before autumn.)
  • Presence of insects. Pests typically lay white eggs in high quantities on the ferns. 

Just because you don’t see these signs at first doesn’t mean you’re in the clear. There are two additional possibilities to consider:

  • You’re dealing with a small-scale infestation in its beginning stages. This is good news, but it’s too early to relax. You’ll need to take timely measures to prevent the infestation from spreading or growing. 
  • The offending pests live in the soil. A few pests snack on asparagus roots exclusively, and don’t usually appear above the ground. 

Inspect Your Asparagus Plants

Inspecting your plants should be a regular part of your gardening routine. However, if you suspect disease or see early signs of damage, you may want to make a more thorough inspection of your plants.

Start by inspecting the ferns and their stems. This part of the plant tends to attract the most insects since it’s where food production occurs. You’re looking out for the signs of pest infestation we discussed above. 

Next, move on to the spears. It’s common for spears to get snacked on, too, especially ones that haven’t hardened. 

Lastly, examine the roots. You’ll have to dig up a few inches of topsoil to see if any pests are hiding down there. 

Common Pests

These are the most common asparagus-infesting pests. If you spot a pest, it’s likely one (or more) of the following: 

Asparagus Aphids

Aphids are tiny winged insects that suck sap from your asparagus plant, taking away nutrition and causing weakness. They also release toxins, damaging your plant’s stem and roots. 

Aphids are very small (0.04 inches / roughly a millimeter) and can be hard to spot until they’ve built up enough strength. 

Farmers keep these pests in check by introducing natural predators, such as ladybugs and wasps. This works surprisingly well when it comes to controlling aphid populations. However, it makes sense not to want to introduce predator insects to your own backyard. 

In that case, you have two options. You can either resort to using insecticide or isolate infested plants and hope for the best. 

An aphid infestation is unlikely to resolve without external intervention, so it’s important to be decisive in how you intend to approach treatment. 


Cutworms are moth larvae. They look similar to caterpillars but are nowhere near as plant-friendly. 

Cutworms live on the soil and feed on the lower extremities of plants – typically the base of their stem and any exposed roots. Asparagus plants are not safe from this threat, so it’s important to keep cutworms out of the asparagus bed by using a physical barrier. 

Cutworms are one of the more dangerous pests. As they chew on the stem, the plant above loses its supply of nutrients and structural support, leading to mass damage. 

Cutworms are a big problem in the early spring when asparagus plants begin growing and can easily be fed on. If cutworms have made it into your asparagus bed, you’ll need to use insecticides to get rid of them. 

Asparagus Miner

The asparagus miner is a fly-like insect. Like the cutworm, it typically feeds on the base stem, which can be problematic. However, unlike the cutworm, it gets active much later in the year. 

The miner most frequently infests asparagus plants in the late summer, after spear-harvesting season. The eggs can overwinter on the plant’s foliage if it isn’t cut back. 

By simply cutting back your asparagus ferns right before winter, you’ll save yourself the headache of dealing with this pest the following year. 

Common Asparagus Beetle

It doesn’t take much to figure out why this beetle was named as such. It frequently infests asparagus plants and has gained notoriety among backyard gardeners and commercial farmers alike. 

The common asparagus beetle is about a quarter of an inch in length (0.64 cm), so you should be able to spot it pretty easily once you’re up close. It’s orange or red in color and has black patches on its lower torso. 

It usually hangs around in the ferny foliage of the plant, although you may be able to find it lower as well. 

Common asparagus beetles tend to show the most activity in the afternoon. That’s when you have the best chances to spot them. 

A more plant-friendly way to deal with them is simply shaking them off the plant. Eliminate the eggs, in particular, since the offspring don’t survive for long if they hatch on the hot ground, with no way to feed. 

For a more serious infestation, you’ll have to use commercial insecticide. Failure to eliminate asparagus beetles can be detrimental to your yield because, in addition to causing health problems, these beetles can lead to thinner crops. 

2. Address the Pest Infestation As Soon As Possible

No matter what infestation you’re dealing with, you must address it at the earliest. Insects multiply rapidly, and infestations can get out of hand much faster than you would expect. 

It’s best to nip small-scale pest problems in the bud, so they don’t develop into something much harder to control. 

If you would like to take a more organic approach, you can attempt to:

  • Shake off pests from your asparagus. This method is mainly effective only with beetles. You can also place a sticky trap underneath the plant to catch the fallen pests.
  • Hand-pick pests off the plant. Wear gloves to be safe.
  • Use soapy water. This will most affect aphids and miners. Beetles and cutworms are too large and might be resistant to the effects of soapy water.
  • Introduce natural predators into the mix. Ladybugs will take care of most of the above pests. 

However, in the end, you may have to resort to chemicals that are guaranteed to work. Note that some pesticides, although effective, can also affect your plant’s health and quality of yield.

Preventing Future Infestations

An asparagus bed can easily last for over a decade, so you should be mindful of a pest control strategy. 

Here are a few expert-vetted tips to help you avoid future infestations:

  • Let your asparagus plants get plenty of sunlight. Many insects prefer shady and moist conditions so they remain cool and hydrated. Direct exposure to intense UV radiation is often too much for them to handle. Exposure to sufficient sunlight is also beneficial to plant growth and will prevent asparagus from falling over.
  • Practice good garden hygiene. Regularly inspect and clean your asparagus bed. Remove any decomposing matter above the soil since it will attract pests. 
  • Set up a physical barrier around your asparagus bed. This can be something as simple as a wall of cardboard. Its purpose is only to prevent entry to insects such as cutworms. 

3. Check for Signs of Infection or Disease

If it turns out your asparagus plants don’t have a pest problem, the next thing to scratch off is the possibility of an infection. 

While asparagus plants are hardy perennials, they are, quite unfortunately, prone to catching a variety of diseases. 

Common Asparagus Diseases

Let’s discuss the most common problems that can cause root damage via rot and decay, giving you the impression that your asparagus roots are being eaten. 

Asparagus Rust

The infamous asparagus rust, also simply called rust, is caused by the fungi Puccinia asparagi. 

It’s one of the most common diseases in asparagus plants. It’s so common, in fact, that plant breeders have been making a conscious effort to develop rust-resistant varieties of asparagus. And their efforts have not been in vain. The newer varieties are indeed more resilient. 

Rust causes the formation of orange or red pustules (think of a pimple but for plants) on asparagus. These pustules eventually turn black as the cold sets in but can survive the winter and cause the disease to make a comeback next year. 

Rust initially affects the stem and foliage. However, if left untreated, it can spread to the roots and crown, damaging the most vital part of the asparagus plant. As such, early prompt treatment, along with ensuring the disease does not overwinter, is essential. 

Here are a few ways to deal with rust-ridden asparagus plants:

  • Cut off stems, spears, and ferns infected by rust. Dispose of the infected limbs carefully. This will minimize the spread of infection. 
  • Remove and isolate a plant if at least a third of its body is affected. This is necessary so that the infection doesn’t spread to your other plants. 
  • Apply fungicide to kill off the infecting pathogen. Fungicidal sprays should generally be applied post-harvest.
  • Cut foliage back down to the ground when it dies in winter. Dispose of the cuttings. This helps prevent rust from overwintering.

Fusarium Crown and Root Rot

This rot disease is caused by soil-based fungi that belong to the Fusarium genus. It’s very common, as the Fusarium fungi can be found in soil worldwide. Not only that, but they also have extreme longevity. They can survive up to three decades in the soil and still infect unsuspecting asparagus plants. 

The infection, as the name implies, is particularly aggressive towards asparagus roots and the crown. It eventually causes most of the root matter to rot, stripping away the plant’s ability to nourish and hydrate itself. 

The infection will manifest above the soil as lesions on the lower stem. Additionally, the ferny foliage above will turn yellow gradually but thoroughly, which is how you’re likely to first notice something’s wrong. 

Fusarium rot is a dangerous disease that can severely impair older plants and kill younger ones easily. 

Asparagus plants undergoing drought stress are definitively likelier to be infected by this disease, which is why adequate watering is one of your best preventative steps as a home gardener. 

Ensure your asparagus plants are getting their needs met. A healthy, well-fed, and hydrated asparagus can much better defend itself against fungi. The fungi exist in the soil almost everywhere, and there’s not much you can do about that. 

Fungicide is of little use for the same reason. It has the best shot at working when the infection is in its beginning stages, but you likely won’t catch it due to the lack of outwardly visible symptoms. 

Unfortunately, this is a case where you can’t really do much to help your infected asparagus plants out. 

Prevention Is Better Than Cure

As I’m sure you can tell based on my description of the two diseases above, prevention is far better than cure. Following good garden hygiene goes a long way. Here are some more specific tips for you as well:

  • Make sure your asparagus plants are well-fertilized and receive adequate hydration. This helps bolster their natural defenses. 
  • Avoid overharvesting spears. It causes the plant to go through great stress, as the crowns have to endure a sudden loss in sugar (food). 
  • Keep the soil in your asparagus bed slightly acidic. A soil pH higher than 6.0 but below 7.0 is optimal. 
  • Cut down your asparagus ferns every winter. This prevents pathogens from returning with next year’s growth. 
  • Ensure you use a sanitary cutting tool whether for harvesting, pruning, or cutting. You can sanitize your cutting tool by cleaning it with diluted bleach (1 bleach to 9 water) or rubbing alcohol.

4. Check Your Asparagus Plant for Signs of Overwatering

Let’s say your asparagus plants have root rot but aren’t showing other signs of infection, such as lesions and pustules. In that case, by process of elimination, the only possibility left is that of overwatering-induced root rot. 

Overwatering can produce the same type of damage as a deadly infection. Essentially, asparagus roots need oxygen to survive. When they’re submerged in water, they can’t get this oxygen. If they stay submerged for too long, they will suffocate and die. This is how overwatering kills roots. 

Because roots are a living part of a plant, they begin rotting after death. This may be what you’re misdiagnosing as eaten roots.

Make Sure the Bed Soil Has Adequate Drainage

Having your asparagus plants rest in well-draining soil decreases your chances of overwatering them. It gives your asparagus roots room to breathe by draining away any extra water in case you accidentally give the plants too much water. 

Needless to say, you can’t do much to change the drainage capacity of the soil in your asparagus bed currently. Selecting a prime spot in the garden beforehand is really key here. 

Mix in Organic Matter To Improve Soil Drainage

Even though you can’t majorly influence the drainage of existing soil, you can improve it slightly by mixing in some organic matter. 

Compost is a great option. Not only will it improve drainage, but it will also act as a natural, slow-release fertilizer. Asparagus plants appreciate having a high organic content in their growing medium. 

Plant Your Asparagus Crowns at an Appropriate Depth

It’s no secret that soils differ greatly in their capacity for water retention. This is something that should be kept in mind while planting asparagus crowns. 

In sandy soil – which drains water rapidly – crowns should be planted at a depth of twelve inches (30 cm). This ensures they can access deeper water reserves.

In clayey soil – soil that holds water very well – it’s best to plant crowns at a depth of six inches (15 cm). Planting any deeper would increase the likelihood of overwatering. 

5. Get Expert Help

Lastly, if you’re still unable to pinpoint the issue despite your best efforts, it would be best to get some expert help. 

Asparagus is a resilient, hardy perennial that can last for over two decades. Its longevity means you’re bound to face health problems sooner or later. Getting help from an expert is never a bad idea. 

Final Thoughts

Losing your asparagus roots to pests or diseases can be frustrating. Here’s how you can accurately diagnose the problem:

  • Look for pests. The asparagus beetle, miners, aphids, and cutworms can all cause lower-stem and root damage. You can treat infestations with insecticide. 
  • Check your asparagus for signs of infection. The two most common diseases are rust and fusarium rot. Management is difficult, so prevention is best. 
  • Check your asparagus roots for signs of overwatering. If your asparagus bed is always wet, let the soil dry out in between waterings. 
  • Get expert help. It’s always best to consult an experienced gardener.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

Recent Posts