Plant Fungal Diseases

Fungus is and always has been an essential requirement to sustain plant life. But there are many fungus types that have adapted in order to target plants, often with devastating effects. Plant fungal diseases are not a new problem and they are the most commonly encountered ailment of most plants types. There are a wide range of fungal diseases that can cause biological warfare in our gardens. Most gardeners will shudder at the sound of the words ‘Powdery’ and ‘Mildew’ – among others – and with reason.

To provide the necessary treatment it is important to first identify the correct disease. A small amount of research can go a long way as most diseases target specific plant families and need baseline conditions to develop. We can exploit this to narrow down which disease may be affecting said plant. Once we understand that we can move onto the specific treatment and how to prevent future outbreaks.

In this post, we will go through some of the readily available natural fixes to plant fungal disease types. Please note that this will not include nutrient related problems and will only work for fungal based infections.

There are a number of consumer brands which claim to solve all of your plant disease problems, some of which are extremely effective. But there can be side effects on your garden’s overall health as a consequence. Among other harsh chemicals which can adversely change the soil structure, Copper Sulphate is a common ingredient in commercial fungicides which can be beneficial, but may also become too concentrated in the soil causing damage or death to plants. The problem here is that Copper Sulphate is only effective against fungal diseases soon after infection, making several applications risky. Luckily there is a better way to do things and they are completely safe to your health and the environment.

Disease Types

There are thousands of plant fungal disease families & strains. They are generally tackled by category as there are so many that control is rarely tailored to one strain specifically. Some treatments may of course work better on some specific fungus and plant type variations, but it can often be the case of trial and error.

You are most likely to encounter the following common fungal disease types:

  • Rust Diseases – As the name suggests, infected plants look as if they are literally rusting. The early symptoms of the fungus are identified by pale specks forming on the foliage developing into spore producing structures called pustules which spread the disease. Brown patches are visible on the foliage in later development to the span of an entire leaf. The symptoms can cause a lack of growth, poor performance and death.


  • Mildews – The most common fungal infection or plant health problem in gardens is mildew. A leaf staining fungus with blotches (usually white) primarily on the lower leaves and stems. The infection sucks the energy directly from the plant causing them to perform poorly and look unsightly. Sometimes fatal to more susceptible or younger plants.


  • Leaf Spot – One less intensive fungal (and sometimes bacterial) problems. Commonly found on roses but affects a wide range of shrubs, trees and other plants. Leaf Spot takes the form of a grey ripening to black circular spot to the size of a penny. The unsightly infection is only visible on the leaves and tends to be clustered around a specific area of the plant.


  • Rots – These form around the roots of plants which mostly end up with fatalities once the disease has taken hold. Plants wilt soon after infection and gradually die as they are broken down and start to rot away. Most commonly found in water-logged soils or indoor plants with poor drainage. Amending the conditions and taking care not to over water is the best preventative measure. Infected plants can be treated by washing the roots and replenishing the soil which can (in some cases) prevent further damage.

Natural Treatments

When it comes to treatment you should keep in mind the reproductive cycle of fungi. There are hundreds of thousands of spores in the air around us all of the time, it would be near impossible to suggest maintaining a spore free zone unless we are talking about indoor gardening. Instead we have to make our environment as unattractive as possible. Even if you did everything possible you would have to expect the odd case from time to time. Our real end goal is to reduce plant losses in the event of an outbreak.

Caution: Always test a small amount of any homemade mix on a single leaf and wait to see the effects, there are thousands of plant types and each is unique in some way that may mean they react differently.

So here’s our favourite environmentally friendly and safe natural remedies…

  1. Apple Cider Vinegar – Mix one tablespoon of vinegar to 4Litres of water and use as a topical spray directly to the plant and infected areas. Especially good for use on black spot. Use sparingly and as needed as the acidity can damage sensitive plants.
  2. Baking Soda – Possibly useful for eradication of mild infections, but very effective at preventing outbreaks. Dilute 4 medium sized teaspoons to one gallon of water and use as topical spray to plants and exposed areas.
  3. Neem Oil – An all around useful essential oil to keep handy. Mix 5ml to 1Litre of water and apply as a spray to affected plants and areas thoroughly. Also acts as a pesticide effective against most garden insect pests including aphids. Use with caution as beneficial insects are also affected, avoid spraying flowers to safeguard pollinators. We recommend to use the recipe once per half year to allow for biological balance.
  4. Onions/Garlic – Organic gardeners take note. All Alliums including the ornamental varieties have strong fungicidal and pesticide properties. Crush several cloves per gallon of water and spray directly to affected areas. Extremely effective against soft body insects and most fungi.


Our responsibility as gardeners…

Simple solutions from harsh chemical products can be tempting while we all take such joy from our gardens. Diseases and pests can be incredibly costly and annoying. But everything has a purpose in the natural world.

There are many other natural ways of controlling disease than we have listed here. It is our responsibility to always take the most precaution to work with our environment in the least damaging way with wildlife and native fauna in mind.





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