Why Is My Lupins Wilting and Dying? [Reasons & How to Fix]

When lupin plants thrive, they display stunning flowers in bright colors that make your garden look that much better. Unfortunately, when they start to wilt and turn brown, they’re not only losing their beauty but their health and longevity as well. This is why you have to figure out what’s ailing your plants to treat them as soon as possible.

Lupins wilt and die because they’re susceptible to diseases and pests. One of the most significant issues affecting lupins is wet soil, which causes fungus to thrive, so you must be careful not to overwater them.

In this article, I will take a deeper look at the main reasons why lupins wilt and die, and provide you with solutions to fix the problems so that they can start thriving.

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Reasons Why Lupins Wilt and Die

There are many reasons why your lupins might be looking unhealthy. Although easy to care for (because they’re drought-tolerant), lupins can attract pests and are also an easy target for various fungal diseases and viruses.

Here are some of the most common reasons why your lupins are wilting and dying, and what you can do.

Your Lupins Have a Fungal Disease

Many fungal diseases can affect lupins. These include powdery mildew and rust. General signs that your lupins are being affected by fungus include bumps, powder, or brown spots on them.

To bring the plants back to good health, remove their leaves that have been affected by the fungus and avoid watering the plant’s leaves as this can encourage fungal growth.

Here are some specific fungal diseases that affect lupins:

Powdery Mildew

This mildew shows up on lupin plants in the form of powdery spots on their leaves that can be white, gray, or black in color. You might also see lesions on your plant that are made up of tiny black dots, known as cleistothecia.

You don’t want to ignore powdery mildew because if you don’t treat it, it can draw nutrients from your lupin, which will cause its leaves to droop and become yellow.

Powdery mildew commonly occurs as a result of overwatering the plant. Make sure you remove any infected leaves and stick to a healthy watering schedule, remembering to water the plant base but not the leaves.

Rust (Puccinia)

This fungus causes brown spots or powdery bumps on the stems or leaves of the lupin plant. It also stunts the plant’s growth. To treat rust, you should use a fungicide as soon as you notice it.

You can also eliminate rust on your plants by applying neem oil to them. Ensure you use a 70-percent clarified hydrophobic extract of neem oil, such as this Monterey 70% Neem Oil from Amazon. It not only treats plant rust but can also be used to eliminate other issues, such as insects and powdery mildew.

Since rust easily spreads between different plants, ensure you disinfect your gardening tools after each use. You can do this by a mild bleach solution.

Root Rot (Sclerotium)

This fungus causes the lupin’s leaves to become yellow, wilt, and die. You’ll notice a cotton-like mass around the plant crown or the soil near the crown, as The Connecticut Agricultural Experiment Station reports.

Root rot is caused by watering errors, especially overwatering. While you should water your lupin regularly, aim to water it once a week if there hasn’t been rainfall in your region.

Anthracnose

This is another fungus variety that is caused by too much moisture, specifically when fungal spores on infected plants are spread to healthy plants via splashes of water. When this happens, brown lesions form on the lupin leaves and petioles, which are the stalks attaching the leaf blade to the stem.

This fungus can make the plant wilt and take on a corkscrew appearance, which is when leaf stalks become twisted.

Treating a lupin plant with anthracnose involves removing the affected leaves if only a few of them display symptoms. If the plant is dealing with a more severe case of anthracnose, you’ll have to remove and dispose of the plant, as the Royal Horticultural Society reports.

To prevent anthracnose problems in the future, plant the lupins further away from each other. This will encourage better air circulation. Additionally, avoid overwatering the plants.

Your Lupins Have a Virus

Some viruses can affect lupin plants, causing them to wilt and die. Here are two common ones to keep an eye out for, both of which are caused by aphids.

Bean Yellow Mosaic Virus

This disease begins in clover patches and is then transferred to the lupins via aphids. So, if you’ve planted clover and lupins in your garden, make sure you separate them. This virus affects the young lupin plants, which will wilt and die. The leaves of the lupin plant will also lose their color and fall off.

To remove aphids from lupins, you’ll need a bug spray to treat them, otherwise, the aphids will continue to feed on the sap from the plants, which can cause them to die. You can make your own bug spray with ingredients you already have at home, such as garlic, which is a potent pest-killing ingredient as it contains sulfur.

A study, via the Journal of the North Carolina Academy of Science, found that garlic worked well as a homemade spray to control aphid numbers on plants.

Here’s how to make an anti-aphid garlic spray.

Chop three garlic cloves.
Mix them with two teaspoons of mineral oil.
Leave the mixture to sit for 24 hours.
Strain the garlic and add the remaining liquid to two cups of water.
Put this new mixture in a spray bottle.
Add one teaspoon of dishwashing liquid.
Spray this mixture to one part of the plant and check for any signs of damage, such as yellowing, for two days. If there are none, use it on the rest of the plant. If there is damage to the leaves, dilute the mixture with more water, as The Spruce recommends.

Cucumber Mosaic Virus (CMV)

Aphids are drawn to lupin plants because of their sap, which they like to consume. If you’ve used tools on an infected plant and then used them on your lupin, this can spread the virus.

The terrible thing about CMV is that it can’t be treated. So, when your lupin plant is showing signs of having this virus, it has to be eliminated and destroyed.

Common symptoms of CMV include discolored and mottled leaves, stunted growth, and necrosis, which is the death of plant tissue and shows up as brown or black areas on the plant.

Your Lupins Are Being Attacked By Pests

There are various pests that can attack your lupin plants and cause them to suffer. Here are three of the most common ones and what you can do to prevent or remove them.

Slugs

If you’ve noticed slugs around your lupin plants, this is because they’re attracted to the plants’ sap. They damage the plants’ leaves and make holes in them. Over time, this can stunt the plant’s growth.

To prevent your lupins from attracting slugs, make sure you plant them in an area of the garden where they’ll receive full sun and a bit of shade in the afternoon.

Growing lupins is especially favorable if you live in a hot region such as Nevada or Texas. The warm sun will prevent slugs and snails from attacking the plants because these pests are drawn to wet, cool areas in shade, as the University of Minnesota Extension reports.

Whiteflies

These are small flies that lay their eggs underneath the lupins’ leaves. They feed on the leaves, causing damage to the plants. If you live in a warm climate in the U.S., such as Arizona, whiteflies can breed throughout the year, and this can lead to a more severe infestation.

You can try a few methods to eliminate whiteflies.

Plant a few decoy plants. These will attract whiteflies, which will leave your lupins alone. Examples of plants that are particularly appealing to whiteflies include geraniums, tomatoes, and fuchsias.
Wash whiteflies that you can see on the lupin plants. Use a garden hose to do so every few days.
Remove any affected leaves. Better yet, destroy them so that you’ll also kill the flies’ eggs.
Remove any weeds near your lupin plants. They provide whiteflies areas in which to hide.

If the above tips don’t work, use a row cover that will let air, water, and light through to your plants but will keep pests such as whiteflies out, as the University of California Division of Agriculture and Natural Resources reports. I’d recommend purchasing the SUNPRO Floating Row Cover from Amazon that protects plants against frost, freeze, harsh sun, birds, and insects.

Conclusion

If your beautiful lupins are drooping or dying, there’s a number of culprits that might be causing the issue, including pests, fungus, and viruses. By knowing the important signs to look for in your suffering lupins, you’ll be able to treat them so they can get a second lease on life.