How to use copper fungicide on palm trees

Copper Fungicide: Why, When, Where and How To Use It

In your search for plant fungus remedies, you’ve likely heard that many gardeners swear by copper-based fungicides. Some say it can be hugely beneficial, and others claim that it can be a little too intense.

Before we address its uses and effectiveness, let’s start from the beginning –

What is copper fungicide? Copper fungicide refers to any plant product with copper sulfate as an active ingredient. When dissolved in water or combined with other compounds, copper can penetrate diseased plant tissue and prevent fungi and bacteria from spreading further since these organisms are sensitive to copper ions.

The main snag of copper fungicide is that it doesn’t break down in the soil as quickly as other fungicide products do, so knowing precisely how, where, and when to apply the stuff is key to treating the early stages of plant disease without killing the plant itself!

Let’s look at how it can be used and how safe it is, and we’ll share our pick of the best copper fungicide products and more.

How Does Copper Fungicide Work?

When converted into a liquid state, copper fungicide kills harmful organisms in plant leaves by “denaturing enzymes and other critical proteins, which kill the pathogen cells,” according to crop specialist Gordon C. Johnson at the University of Delaware.

Copper Fungicide Uses

Ideally, copper fungicide should be applied to plants before the signs of fungal infection are visible as it is predominantly a deterrent product, but you can also use it immediately on plants that display early signs of infection.

Many gardeners also apply copper-based fungicide to plants or trees that are nearby a diseased plant as a preventative measure.

Is Copper Fungicide Safe for All Plants?

Every copper-based fungicide product has different strengths and applications, but as long as the directions are followed correctly, it will be safe for all plant types.

When used in large quantities, the copper element can cause “phytotoxicity,” killing or severely damaging plant tissues.

Other factors can make copper applications a little more risky, such as using it on new leaves, wet leaves, or during wet weather periods when the product hasn’t been able to dry sufficiently.

Gordon C. Johnson explains that “copper ions are released in small amounts when copper residues are wetted, sending them to other areas of the plant to penetrate cells. Copper injury is also most likely on new leaves and leaf edges that have thin, undeveloped cuticles (the outer protective waxy layer).”

What Plants Can You Use Copper Fungicide On?

Copper fungicide can be used on most houseplants, vegetables (particularly squash and cucumbers, tomatoes, eggplants, and potatoes), fruit plants/trees, herbs, ornamentals, and your lawn.

Avoid use on copper-sensitive plants, however, such as bromeliads, ivy, and annual geraniums.

Copper Based Fungicide for Trees

Copper-based fungicide products for trees are commonly in a “fixed-copper” spray form, but it can also come in a blue paste known as Bordeaux mixture, which combines copper and lime and is often applied to trunks with a wide paintbrush.

Preventative sprays are normally applied to trees during winter to take advantage of cool, dry periods and the tree’s dormant state.

How Do You Apply Copper Fungicide to Indoor Plants?

Firstly, remove badly infected sections of the plant using sterile pruning shears (making sure to clean your tools after use to prevent spreading mold spores).

Allow the plant to completely dry in a warmer room with good air circulation before taking it outside and spraying it all over with the fungicide.

Only bring it indoors once it has dried again. Keep affected plants isolated to avoid spreading fungal spores to healthy ones.

When Should You Not Use Copper Fungicide?

As copper fungicide is a deterrent and not a cure, it won’t always be effective on plants with a late stage of blight.

Conversely, copper fungicide should not be something you reach for when minimal marks/spots appear on leaves as this could be controlled by trimming or pruning the affected areas and monitoring for possible spread.

So be sure you have correctly identified the disease on your plant before using copper fungicide in haste.

Is Copper Fungicide Safe for Humans?

When used in small amounts and as directed on the label, copper fungicide is perfectly safe for humans.

Products often recommend wearing protective gloves and clothing, masks, and eyewear when applying as it has been known to cause eye/skin irritation.

Is Copper Fungicide Organic?

Though copper fungicide has been approved under the USDA National Organic Program, it is technically classified as a synthetic.

According to the Organic Program list, copper-based plant control “must be used in a manner that minimizes accumulation in the soil.”

This has divided many organic growers since copper sulfate is still a much-relied-upon fungicide.

Is Copper Fungicide Safe for Bees?

Copper fungicide is generally safe for bees but only when it is applied to plants or trees late in the day when bees are not actively pollinating or foraging.

This allows the product to dry before bees return to pollinate.

Copper Fungicide vs. Neem Oil

While copper fungicide products combine copper with added compounds such as salt and acid, neem oil is a naturally-occurring fungicide found in the seeds of the Azadirachta indica, or neem tree, native to India and Africa.

Here’s how they compare:

How Often Can You Apply Copper Fungicide?

Generally, most spray products suggest applying copper fungicide weekly or every 10 days until symptoms disappear.

Whenever possible, at least 12 hours of dry weather should follow a copper fungicide application.

When To Apply Copper Fungicide to Fruit Trees

For best results, copper fungicide should only be applied as a preventative measure in the fall or before leaf emergence, according to the Tree Fruit Advisory Extension at Utah University.

As the young foliage and flowers on fruit trees can be damaged by copper, applying fungicide specifically at bud break or immediately after planting is best.

As for dealing with early symptoms of disease on mature plants, copper fungicide can safely be applied every 7-10 days up until harvest.

Copper Fungicide Spray – How To Use

Typically, most copper fungicide products come in a ready-to-use spray.

Otherwise, they will come in a bottle of concentrated liquid copper that normally advises mixing 0.5 to 2 ounces of the liquid per gallon of water in a spray bottle (taking care to use protective gloves and clothing).

You can then spray the solution directly onto your plants when you first notice the symptoms of fungal infection – targeting the tops and undersides of the leaves – and repeat weekly.

Always follow the guidelines set by the manufacturer as each product may vary in terms of dosage and may mention certain weather or temperature limits for the fungicide to be used to best effect.

Best Copper Fungicide

There are many different copper fungicide formulas out there in liquid, paste, and powder forms – each one containing varying levels of copper, different active ingredients, etc.

If you’re not sure where to begin, here are three we’d recommend:

Bonide Copper Fungicide

This 16-ounce liquid concentrate has a low concentration of copper soap (10%) and can be used right up to the day of harvest to tackle many common and uncommon plant diseases and can even be effective on late-stage blight.

The product mixes instantly with water so you can use it immediately with a hose-end/tank sprayer.

Bonide Copper Fungicide also comes in a dust product to mix with water or apply using a dust miser and a ready-to-use spray too!

Southern Ag Liquid Copper Fungicide

Southern Ag’s 32-ounce liquid copper concentrate contains over 27% copper diammonia diacetate, making it super tough on mildew, rust, black spot, and many more stubborn fungal infections.

It can even be effective on algae on your lawn and kill moss on live oak trees.

Simply mix in with water, and use as a cover spray using a hose-end sprayer to apply to your favorite fruits, vegetables, and ornamentals.

Monterey Liquid Copper Fungicide

This 32-ounce, ready-to-use spray by Monterey allows you to apply diluted fungicide solution directly and safely onto your plants from the bottle thanks to the easy trigger spray nozzle.

Use as a preventative dormant spray or apply during the growing season on a wide range of vegetables, fruits, and flowering plants – this aims to control many listed plant diseases from peach leaf curl and fruit rot to rust, downy mildew, and more!


Copper fungicide can be a very effective preventative when it comes to keeping many of your plants and trees disease free.

It’s also very strong, risking overkill when used in large amounts, so be sure to use it sparingly, and make sure you have correctly identified a fungal infection on your indoor or outdoor plant before applying it.

What Is It and How Do You Use It?

In warm, wet weather, fungal disease tends to plague garden plants. 

Rather than using dangerous chemical fungicides, many gardeners choose to use copper fungicides. 


It may surprise you to know even though it is a metal; copper can dissolve in a way allowing it to penetrate deeply into plant tissues to provide optimal prevention and control of a wide variety of fungal diseases, such as:

  • Septoria Leaf Spot
  • Powdery Mildew
  • Downy Mildew
  • Anthracnose
  • Black Spot
  • Fire Blight

When used correctly and at the right time, a liquid copper fungicide provides good protection against these particular diseases, but there are some considerations to keep in mind.

#1 – Limited effectiveness: When using a Copper fungicide, timing is an important consideration.  

For example, this type of fungicide is not especially effective when used against the late blight of tomatoes and potatoes.

#2 – Toxicity: You must be very careful to follow packaging directions precisely because copper is toxic. 

If used incorrectly, it can cause a great deal of damage to plant tissues.

#3 – Varying product results: There are many different types of copper products available, and these vary a great deal in terms of rate of application and the amount of copper and other active ingredients included. 

For this reason, you must review packaging directions every time you use a copper fungicide, especially if you are changing from one product to another.

#4 – Soil contamination: You must use copper fungicide very sparingly because it doesn’t break down in the soil. 

Over time, it builds up and becomes a hazardous contaminant.

What Damage or Condition Does Copper Fungicide Control?

It’s important to understand copper fungicide is a deterrent for diseases like bacterial black spot, not a cure.  

It’s best to set a regular schedule of use to prevent and control the development of fungal infections. 

It will not cure existing infestations.

If you catch a fungal disease (based on early symptoms or conditions) very early on, before you see the fungus, it may be helpful. 

Otherwise, use it as a safeguard early on when weather conditions would predispose your plants to develop the fungal disease.

You may also want to use it as a preventative on healthy plants if you see fungus on one plant or if you have accidentally brought in a plant with a fungal infection. 

In this case, you would want to remove the infected plant and treat the rest with copper fungicide.

How and When To Use Copper Fungicide?

Generally speaking, you would mix 1 to 3 teaspoons full of copper fungicide with a gallon of water to be used as a spray application.  

As noted, these are just general directions. 

Remember always to read the specific directions for the product you are using every time.

These products tend to degrade within a few days of application, so they must be reapplied for the best results. 

Most copper fungicide spray products are applied on a weekly basis. Apply some every ten days.

Even though copper fungicide is not known to be harmful to bees, we must be careful to protect the dwindling bee population in every way possible. 

For this reason, you should never apply copper fungicides to plants where bees are actively gathering pollen.

Apply the products late in the day after bees, and other pollinators have stopped foraging. 

This will give the product time to dry out before they begin hunting for pollen again when the sun comes up.

When in Doubt Seek Help

Many gardeners swear by copper fungicides as a way of keeping fungal infections (anthracnose) under control and protecting Hemlock type plants such as eggplant, potatoes, and tomatoes, as well as squash and cucumbers.

The use of copper fungicides is used in organic gardening is a little bit confusing. As long as you’re very careful about following packaging instructions, you should encounter few problems. 

If you have questions about the use of copper fungicide in your specific situation, get in touch with your County Cooperative Extension Office to find out exactly what is recommended in your area.

Resource: Copper Fungicide Technical Fact Sheet

insecticides, fungicides, herbicides. What and when to use?


Some curse, others appreciate as a very effective remedy against weeds, pests and fungal diseases: herbicides, insecticides and fungicides. These three terms are easy to decipher if we add that in Latin caedo means to kill, herba means grass, insecta means insects, and fungus means fungus. These and many other means used to control pests and plant diseases are the so-called pesticides.


1. Insects - applications and interesting facts

These substances are used to control insects in both the adult and larval stages. Insecticides are used to protect organic materials not only in agriculture and forestry, but also in warehousing. In this way, for example, wood is protected from insects. Another area where chemicals are used is horticulture and potted plants.

The introduction of chemical insecticides into agriculture led to a rapid increase in food production in the 20th century. However, it quickly became clear that the price of this progress was very high. The impact of some insecticides on the environment is so harmful that their use is banned worldwide. Back in the 1980s, spraying forests during the gradation of spruce shrews or moths not only harmed the harmful larvae in the tops of the trees, but also all other insects, and even birds. Currently produced insecticides are predominantly selective (acting only on certain species) and eventually self-destruct.

Contrary to what you might think, insecticides were not invented in the 20th century. Plague insects have been known to mankind since ancient times. Biblical texts mention the gradation of locusts in Egypt. Homer reports on the use of sulfur to protect plants from pests. The Greeks and Romans also used sulfur mixed with oil to control insects. Marco Polo noted that in China, insect pests were fought with arsenic. In the nineteenth century, salts of copper began to be used for this purpose, and later of lead, iron and mercury. The first synthetic effective insecticides appeared in 1930s.

2. Types of insects.

In addition to chemical insecticides, whose action is based on chemicals harmful to insects, there are biological plant protection products. They contain fungal spores, bacteria or viruses.

Insecticides either kill insects or prevent their further development. Depending on the way in which they enter the body of an insect, they can be divided into four groups.

stomach insecticides. They exhibit a toxic effect after insects eat poisoned plants and enter the digestive tract.

Contact insecticides. They easily penetrate the epidermis of the insect and lead to its death.

Respiratory insecticides. They enter the body of the insect through the spiracles in the form of gas or vapor. They destroy all stages of development, except for eggs.

Systemic insecticides. Through the roots and leaves, they move through the vascular system of the plant, making it poisonous to the insects inhabiting it.
This division of insecticides is arbitrary, since most of them penetrate the insect body simultaneously and in different ways.

Application of fungicides.

This is how the means used to combat harmful fungi that infect plants are determined. This group includes both organic and inorganic substances, as well as biochemical agents. Fungicides can completely suppress the growth of the fungus or temporarily stop it. The mechanism of action depends on the concentration of the active substance. Many fungicides can exhibit a fungistatic effect, as a higher concentration of the drug can have a negative effect on plants. Fungicides are used, among other things, in horticulture, agriculture and forestry to protect crops, as well as to protect wood from fungi.

Pesticides should only be used when absolutely necessary.
2. Types of fungicides.
Due to the huge variety of fungi and very complex problems, fungicides have been developed in recent decades that are useful in a variety of applications.

protective fungicides. The term is used as a prophylactic against fungus. That is, the fungicide is applied before the spores of the fungus begin to develop on crops.
contact fungicides. The active ingredients of these fungicides act at the point of contact with the fungus. Contact fungicides do not penetrate deep into the plant, but remain on its surface. The disadvantage of this is that the fungicide can be washed off by rain or artificial irrigation. In addition, newly developed parts of the plant, such as leaves, are not protected and must be sprayed again.
systemic fungicides. Of great importance are fungicides, the active substances of which penetrate into the plant from the soil through the roots or through the leaves. They are then distributed through the transport system of the plant, mostly with water from the bottom up.

Herbicides - weed control

Application of herbicides.
Cultivated plants artificially brought into fields and beds must constantly compete with weeds for water, nutrients and light. Locally adapted weeds grow profusely and must be eradicated manually, mechanically, or using herbicides. There are selective herbicides that act against specific species, and broad-spectrum herbicides.

soil herbicides.

The active substances of this group of herbicides are absorbed by weed roots or germinating seeds. For this reason, soil herbicides are used on surfaces not yet weeded and at the latest when plants emerge. They have a very long lasting effect. They are often combined with contact preparations.

foliar herbicides.

There are two types of herbicides in this group: contact herbicides and systemic herbicides. The first of them act only on the parts of plants treated by them, which die off after a few days. The surface is recommended to be sprayed evenly. Warm and dry weather increases the effectiveness of treatment. In turn, systemic herbicides have a wide spectrum of action on seed and root weeds, both monocotyledonous (grass) and dicotyledonous. Due to the transport of active substances through the roots, they also fight stubborn weeds. Efficiency increases in wet and warm weather.

Combined drugs.

This group of herbicides consists of a combination of foliar and soil treatments. They have a longer duration of action than pure foliar herbicides.

Use of plant protection products

Even commercially available fully legal crop protection products are only safe when used correctly. These principles for the safe use of pesticides include:

Use plant protection products only when absolutely necessary.
Optimum selection of measures for specific needs.
Use only as much agent as necessary to achieve the goal.
Use of efficient spraying equipment.
Only those pesticides that are intended for these purposes can be used in everyday life and in a small garden. Only a few products used in agriculture can be used to protect garden and potted plants in an apartment.

Mistakes in the use of pesticides.

1. Using incorrect measurements due to misdiagnosis.

When it happens that an amateur gardener complains about the poor effect of the remedy used, the reason is often very simple: either the disease was misdiagnosed, or the correctly identified pathogen was treated with a remedy not intended for it. When using an aphid control for caterpillars or a downy mildew agent, it is not only plants that will suffer from downy mildew. Also people, the environment and your own wallet, which you will have to reach for the second time.

Even if the pathogen has been correctly identified, one should consider whether it is worth fighting it with chemicals in the conditions of a personal plot. For example, aphids on ornamental shrubs are mostly an optical problem - they can sometimes be knocked off with a jet of water.

2. The use of pesticides in case of improper cultivation.

Often a tool designed to protect a particular crop is used contrary to its intended purpose. For example, the owner of the garden decided to fight aphids on lettuce with a preparation to combat aphids on roses. This does not comply with the manufacturer's instructions and is hazardous to health. Agents intended to control pathogens on plants intended for human consumption have strictly defined periods of application related to the time of harvest.

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The rooms where we spend most of our time emit quite a lot of harmful substances of various nature. Indoor plants contribute to the removal of harmful impurities that are not desirable for health. In addition, they produce a beneficial effect on the psychological state - the green color calms and gives the eyes a rest. The room maintains optimal humidity due to evaporation from the soil and leaves of plants.