8 Best Fungicide Prevents Cactus Rotting, According to Experts

Best Fungicide Prevents Cactus Rotting

My greenhouse was perfect. Inside, I had several cacti but only one was developing what looked like a fungal infection. A Google search led me to treat the infection with a fungicide and in just two days, the affected plant showed improvement. I don’t have time to waste in my greenhouse and can’t afford to lose any plants by letting them rot, so I’m going to show you what worked for my cactus and how you can prevent your own cacti from rotting!

One of the most common diseases you’ll find in cacti and succulents is rotting. It usually starts from too much water or improper watering. If you notice that your plants are beginning to rot, it’s important to act fast so you can save its life.

Cactus are sensitive plants and they don’t react well when met with rot prevention. Rot prevention should be a top concern if you want your cacti to thrive. I’ve learned that one of the best solutions is a fungicide. Not only will it help prevent rot but it will also help keep the cactus alive when pests infest them. This blog post talks about what I use to prevent rotting and why you need it on your cacti.

EDITOR’S CHOICE: Bonide 811 Copper 4E Fungicide 16oz (473ML)

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Bonide 811 Copper 4E Fungicide is a liquid copper fungicide that helps control powdery mildew, downy mildew, black spot, peach leaf curl and rust. This copper-based product is designed for use in organic production systems to help naturally control those listed diseases.

Bonide’s Liquid Copper 4E Fungicide is designed to kill fungi and other plant pests. The active ingredient, copper octanoate, is a naturally occurring chemical that works as a fungicide. This makes it safer for you and your plants.

Liquid Copper is a natural fungicide and desiccant with no harmful effects on most plants, animals or humans. The active ingredient of Liquid Copper is Copper Octanoate, or Copper Soap. Copper is a naturally occurring chemical which makes it a much safer option for use on all of your plants.

Bonide 811 Copper 4E Fungicide is a effective and fast-acting fungicide that is designed to control Phytophthora, Pythium, Sclerotinia and other fungal diseases that can cause your plants to get sick and die. Just mix this product with water and apply it using either a hose-end sprayer or a tank sprayer.


Great product For a large application.
 It also works on fungal issues with a hawthorn tree.
Do a great job of preventing fungus from infecting new plant tissue.
This product was easy to apply using the supplied directions.
These are easier to use than similar chemicals. 
The copper rinses out clean from sprayer.
The oil is usable at higher temperatures than others.


This stuff is pricey, but it definitely works.

Why Best

 Ordinary fungicides didn’t make a dent in the problem, but this product killed the blight very quickly.

Very specific label which helps and it is effective, just dilute in water.

2ND BEST: Trifecta Crop Control Ready to Use Maximum Strength Natural Pesticide, Fungicide, Miticide, Insecticide, Help Defeat Spider Mites, Powdery Mildew, Botrytis and Mold on Plants 32 OZ Size

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The all-in-one solution to prevent and control spider mites, aphids, and other insects. Trifecta Crop Control Ready To Use is a ready-to-use spray formulated with an organic soap that has been laboratory tested for both efficacy and safety. When pests come in contact with this product, it will clog their breathing cells so they suffocate to death within minutes. It can be used both on foliage including the underside of the leaves, as well as on the surface of growing mediums.

This Ready To Use formula is diluted at a maximum strength of 2oz per gallon ratio. Simply point and spray, then thoroughly wet the plants until foliage is dripping including the underside of the leaves and the surface of the growing medium.

Crop Control is the natural growers’ choice to help protect and cure Powdery Mildew, Spider Mites, Russet Mites, Broad Mites, Botrytis, Grey Mold, Aphids, and fungal and parasitic species on plants.

Trifecta Crop Control Ready is a safe and effective fungicide that helps eliminate mildew and mold in your garden, greenhouse or home. Use it on fruits, vegetables, herbs, spices, roses, flowers and more. Trifecta works quickly without harming the environment around it, so you can eliminate harmful pathogens without harming your plants.

Formulated with organic ingredients to safely target and kill mildew and fungus, this ready-to-use product is safe for use on most plants, including fruits, vegetables, herbs, spices and more. Trifecta Crop Control should be diluted with water and sprayed directly onto affected plants.

FARMER RECOMMENDED – Unique blend of food-grade PREMIUM essential oils including garlic, thyme, clove and peppermint oils broken down to NANO-SIZE particles for MAXIMUM COVERAGE. Crop Control is made with natural food-grade ingredients so you can feel good about what you are putting on your plants and the planet.


Good odor.
Easy to use!
It dissipates quickly. Much better than chemical-based pesticides. 
An even coating of oil and water that has been properly diluted will kill insects on plant leaves.


More on the more expensive range. I wish they were less expensive.

Why Best

Works fine.

General pests are reduced.

 More expensive than top-shelf booze, but it works!

It doesn’t have a bad smell at all. 

3RD RECOMMENDED: Garden Safe Brand Fungicide3, Ready-to-Use, 24-Ounce, 1 Pack

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Garden Safe Brand Fungicide3 is an OMRI listed organic garden fungicide that protects plants from wilt and blight caused by fungus, and promotes healthy growth. Can be used up to day of harvest.

Garden Safe Brand Fungicide3 Insecticide/Fungicide/Miticide is a powerful, easy-to-use product that you spray on your plants to keep them healthy and free from pests, fungus and mildew. It’s suitable for indoor and outdoor use on vegetables and flowers—and it won’t burn your plants!

Garden Safe fungicide is a broad-spectrum, systemic fungicide for use on roses, flowers, houseplants, ornamental trees and shrubs, fruits and vegetables. Protects against powdery mildew, black spot and blights on roses; powdery mildew on fruits and vegetables; black spot on pears and apples; rusts on azaleas; downy mildew on cucumbers; blight and leaf spots on ornamental trees.

PREVENTS LISTED FUNGAL DISEASES: Apply weekly to every 2 weeks until the potential for disease is no longer present.


This stuff is an absolute miracle worker!
Works wonderfully!
Didn’t smell the best, but that’s why it worked.
Bugs did not like it!


Need to reapply frequently and use with sticky traps for gnats.

Why Best

Great packing, shipping, and delivery.

Works well and usually, a one-time use will take care of the problem.

BioAdvanced 701270A Effective Fungicide with Disease Prevention Fungus Control for Lawns, 32-Ounce, Ready-to-Spray

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Bio Advanced 701270A Effective Fungicide provides a broad spectrum of fungus control for lawns. It can be applied for both curative and preventative purposes to treat listed lawn diseases.

Bio Advanced 701270A Effective Fungicide cures and prevents listed lawn diseases prevalent in the United States including leaf spot, brown patch, dollar spot and more. This broad-spectrum fungicide provides long-lasting control of fungus-related diseases such as dollar spots, leaf spots, brown patches, and a variety of other diseases.

Bio Advanced 701270A is a fungicide that protects your lawn against lawn diseases for a month. This product can be used on its own or in combination with other products to provide maximum protection.

Disease control: fungicide controls a red thread, brown patch, dollar spot, rust, and other listed diseases.

Rainproof protection: systemic fungicide is absorbed by grass and will not wash off.

Treats up to 5,000 sq ft.


No mixing is necessary and ease of use
Great for the lawn.
Cleared the Fungus up!
like easy to use use it for lawn fungus.
Works well, is easy to use, and takes care of the problem quickly.


One bottle emptied in less than 2500 sq ft.

Why Best

This stuff worked well.
It works but give it time.

Bonide 775 Copper Fungicide Rtu Natural 1 Qt

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Bonide 775 Copper Fungicide Rtu Natural 1 Qt is a liquid alternative to sprays and dusts for use on flowering and fruiting plants. This product controls powdery mildew, downy mildew, black spot, rust, and many other listed diseases.

Bonide 775 Copper Fungicide Rtu Natural 1 Qt is an active ingredient in the liquid formulation, which controls plant diseases by inhibiting rust, leaf spots, damping off, and many other listed diseases. The best results are achieved when applied before symptoms of the particular disease appear.

Bonide 775 Copper Fungicide RTU Natural is a systemic, non-toxic formula that offers 24 hour protection to prevent and control the growth of a wide range of fungal diseases on listed vegetables, roses, fruits, nuts and herbs.

Its unique mode of action provides disease protection up to the day of harvest. This product can be used on edible plants and even applied up to the day of harvest, so you can get out ahead of any potential problems your plants might face this growing season.

CONTAINS COPPER – The active ingredient of Liquid Copper is Copper Octanoate, or Copper Soap. Copper makes a great option for use on all of your plants.


No more brown leaves.
This product worked like a charm.
it works fantastically.
works great but had to keep reapplying 
The sprayer is too fine.
Easy to use.


Worked on one plant but not another type of plant with fungus.

Why Best

Easy to use, works well, great quality.
Killed leaf spot and early blight in its tracks.

Daconil® Fungicide Concentrate 16 oz. – 100523634

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Daconil Fungicide Concentrate 16 oz. kills stops and prevents over 80 plant diseases on ornamentals, vegetables, fruits, and field crops. Daconil fungicide is powerful enough to effectively control common turfgrass diseases such as brown patch, dollar spot, and many others.

DACONIL Fungicide Concentrate is an effective termiticide and mite control product that kills more than 80 plant diseases such as Botrytis, leaf spots and rusts (including pythium), peach leaf curl and powdery mildew. This can be used for dormant, pre-bloom and rotational spray programs to protect your plants all year round.

Controls most common fungal diseases, including leaf spots, rusts and blights as well as many other diseases. Daconil Fungirol Concentrate is an extremely effective broad-spectrum fungicide for use on flowers, vegetables, shrubs and fruit trees to control Leaf Spots, Rust, Blights, Fruit Rot, Mildew, and many other diseases. It requires only a light spray application for maximum effectiveness.


Took care of the fungus.
Great for battling Photinia Hedge disease.
Easy to mix, good value for the money.
Worked as expected. 


 Reapplication may be needed after rain.

Why Best

Can be used in many plants, shrubs, and trees. 

Great product for the gardener.

Southern Ag Liquid Copper Fungicide, 16oz – Pint

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Southern Ag Liquid Copper Fungicide is a fast-acting and highly effective product that controls diseases caused by bacteria and fungi. In addition, this product also works well with hose end sprayers and is labeled for control of moss and algae as well as other diseases such as rusts, pythium, patch, and Phytophthora.

Southern Ag Liquid Copper Fungicide is an effective, low-risk solution to the problem of fungal and blight diseases. Southern Ag Copper Fungicide is designed to find the correct balance between killing fungus, bacteria, and algae with a minimum impact on the environment.

This new formulation targets mold and mildew without over-drying. It is safe for many plants including ornamentals and fruit trees. In addition, it will not harm beneficial insects such as bees or butterflies.

Contains 31.4% Copper Ammonium Complex (8% Metallic Copper Equivalent).


This stuff works great, has no smell 
it was very easy to mix. 
Great for controlling fungus on fruit trees and vegetables


Pricey for the amount you get, but worth it if it works. 

Why Best

You need to apply to a fully wet, dripping, state.

Bonide (BND883) – Fungal Disease Control, Fung-onil Multi-Purpose Ready to Use Fungicide (32 oz.)

You can order here

Bonide Fung-onil Multi-Purpose Fungicide is highly effective for the control of a broad spectrum of vegetable, fruit, and ornamental plant diseases. It provides miticidal, antibacterial and antifungal action on more than 100 different diseases caused by fungi, viruses and bacteria. Fung-onil contains a low-odor polymer carrier that helps reduce potential overspray drift problems.

PLANT PROTECTION – Designed for use on a variety of plants, such as beans, tomatoes, potatoes, onions, corn, azaleas, eucalyptus, maple trees, daisies, geraniums, roses and many more.

Bonide Fung-onil Multi-Purpose Ready to Use Fungicide (32 oz.) is a non-irritating and environmentally conscious fungicide that controls diseases such as black spot, botrytis blights, anthracnose, rusts, powdery mildews and scab. Extensively used in the nursery industry this multi-purpose formula can be used on tomatoes and roses, nursery stock, ornamental trees and shrubs.

Bonide (BND883) – Fungal Disease Control is a ready-to-use fungicide designed to prevent and control fungal diseases on plants. It contains Chlorothalonil, which is a compound mainly used as a broad spectrum fungicide. Much like sulfur and copper, it is one of the most commonly used fungicides in the United States.

Bonide Fung-onil Multi-Purpose Ready to Use Fungicide is a powerful fungicide used to control plant leaf spots, fruit spots, turf diseases and outdoor ornamentals. The convenient spray nozzle makes it easy to deploy this product. The ready-to-use formula means that no mixing or pouring are required when using this product.


Great for controlling fungus on fruit trees and vegetables.
It works perfectly, everything stayed nice and green.
It takes care of the mildew and kept it mildew free for weeks then I just spray again.


Only use it when the weather is hot.

Why Best

Get greener leaves and blooming.
It worked great getting rid of his fungus

Cacti Fungus Symptoms

Root and crown rot

Fungal diseases are most often caused by members of the genus Phytophthora, which act as water molds. The fungi live in the soil and infect plants through their roots or crown. Crown and root rot diseases are difficult to treat and often result in the death of the infected plant. Phytophthora fungi are some of the most destructive pathogens of succulents, causing a variety of crown and root rots.

If you have cacti, you need to know how to tell if they have been infected by Phytophthora fungi. If you see wilting, leaf discoloration, or blackening that is not accompanied by signs of freezing temperatures, it could be a sign that your cacti have been infected by one or more members of the Phytophthora genus. In order to diagnose fungal diseases on cacti, it is essential to examine them in the early stages and before they have a chance to progress too far.

Phytophthora-infected succulents are usually very difficult to cure once they reach an advanced stage. However, if you catch them early enough and repot them into well-draining soil with ample drainage holes, you can avoid root rot or crown rot in your succulents.


The fungus Fusarium oxysporum prevents succulents from absorbing water, which results in extreme stress, withering, turning yellow, and occasionally plant death.

This fungus enters the plant through the roots and starts to grow in the vascular tissues after being spread by excessively moist soil. Succulents eventually experience blockage in these tissues, which makes water transportation challenging or impossible. Brown streaks can be seen if the tissues are opened.

The healthy part of the plant should be cut with a previously cleaned knife and planted as a cutting in fresh soil in order to stop the spread of the disease. In order to prevent infection, it is also advised to apply a fungicide to the cut.

Gray mold (Botrytis)

Gray mold (Botrytis cinerea) is easy to identify by its gray-brown spore masses that form on the leaf and flower surfaces of affected succulents. Gray mold is most common when the weather is cool and damp in early spring or summer.

They usually enter through wounds or micro-wounds. After a hailstorm or heavy rain, wounds are produced where the fungus enters. To prevent the infection of these fungi, we must protect our plants and apply, the day after the rain or hailstorm, a fungicide.

Leaf Spots on Succulents and Cacti

We’ve all seen them: those little tan blotches on the leaves of our favorite potted plants. Most people don’t know what causes those stains, or why the spots are harmless despite their unsightliness. The good news is that succulents are often resistant to leaf and stem spots, so you can buy a new plant without worrying about whether the spotted one will spread its condition to your garden.

Leaf and stem spotting can be caused by many different fungi. The spots are harmless to the plant, although they’re easy enough to remove by hand. Removing the spots won’t make them go away—they’ll continue to return unless you treat your entire collection with a fungicide. If you have an individual plant with spots, the best course of action is simply to remove the affected leaves and dispose of them. If the spot is large enough that it’s dominating the look of your succulent plant, you may want to replace it so that it doesn’t spread to other plants in your collection.

Black mold on succulents and cacti

Mold is a fungus that grows on various food products such as cheese, bread, and fruit. It can also grow on cacti. In the case of cacti, it is usually found on the surface of the soil.

The growth of mold is usually caused by insects called aphids, mealybugs, whiteflies, and scales. These insects secrete a sweet substance called honeydew. This substance promotes the growth of molds. Molds can be easily cleaned with a damp cloth or rubbing alcohol. If left unchecked, mold can prevent your cactus from receiving enough light, thereby impeding the process of photosynthesis and preventing it from producing adequate nutrients and finally turning yellow.

Types of Fungal Damage in Cacti

The enormous variety of mushroom species is the only thing that can compare to the immense number of cactus species. Cactus pads frequently develop fungus spots, such as the Phyllosticta pad spot. The specific fungus that is generating the spots is frequently quite difficult to identify, but it rarely matters because the treatments are typically the same.

Once their visual damage is evident, certain fungi are too late for the plant since they can harm the roots and even the entire plant. Simple topical fungus spots are much easier to treat and, as long as the offending fungus is under control, usually pose no harm to the cactus’ existence.

Cacti can develop lesions in a variety of ways. They can have any shape, including round, angular, elevated, flat, and others. Many are discolored, but once more, the hues might be anywhere from yellow to brown to completely black. Others are watery, while others are corky. These could exude a dark, rusty, or brown liquid, which would indicate a severe infection.

Opuntia and Agave cacti are the most frequently affected by fungal infections. On cacti, fungus lesions typically start as water spots or mild discolorations on the plant’s epidermis. The symptoms can grow over time as the fungi develop and spread, even eating away at the cambium when the surface skin breaks down and allows the pathogen to penetrate.

Causes of fungal lesions on the cactus

Cacti are a popular choice for both indoor and outdoor plantings. When they are placed outside, they may be exposed to a wide variety of fungal spores and may become infected. This is especially true if they are grown in areas with high levels of humidity or in wet atmospheres. Some spore types can survive for long periods of time when not in contact with the plants that they infect—others have atmospheric lifespans and exist only briefly.

Fungal spores can be carried by the wind or can be in the ground near your cactus. Exposure to water may also be a vector for infection. The combination of high humidity and warm temperatures will increase the likelihood of fungal development on your cactus. 

Cactus pads that are constantly moist and warm are particularly susceptible to infection when their surroundings contain fungal spores. Overhead watering and greenhouses with poor ventilation will also allow fungus formation to thrive.

Soil is another contributing factor. Many soils harbor fungal spores, which can persist for years until the right conditions occur. Even purchased potting soil can be contaminated with fungal spores.


We hope this article on the best fungicides for cactus rot helped you gain some useful knowledge about how to prevent your cactus from rotting. They are among the best on the industry and will surely come in handy for sure. Get the best for your plant today before the damage is already done.

Fungicides are the best way to prevent the rotting of your cacti. However, you must pay attention to their application. Do not use a fungicide if there are wounds or injuries in the plant. Before making an application, check for possible damage and wounds. Otherwise, follow the instructions provided by the manufacturer and spray on a preventive basis every few months.

Tips: While pesticides and fungicides are important tools in any gardener’s arsenal, as they prevent infection and keep plants healthy and disease free, they do come with certain risks. Chemicals that are used in pesticides or fungicides can be highly toxic to humans and many animals. Pesticides may also have the potential to linger in the environment for a long time after use. This is why it is always better to choose organic alternatives such as non-chemical chemicals and biological pesticides whenever possible.

Anwar Hossain

My name is Anwar Hossain. I am a cactus lover, researcher, and cactus blogger.

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