Japanese maples should now be showing their first hints of autumn colour, but it will not be able to grow its beautiful foliage if gardeners do not keep an eye on its leaves. September is when the weather starts cooling down, but it is still warm enough after summer to have humid nights, which can create the perfect conditions for fungal diseases.
Powdery mildew looks like a dusty coating on a tree’s leaves and grows on plants with poor air circulation, so is common on Japanese maples due to how bushy it is in autumn. This infection will cause fungal spores to fester on the leaves and cause them to curl up or drop off early, which will cause tree will look bare instead of having its striking red foliage.
However, the most serious consequences of powdery mildew is that it blocks light from reaching the tree so it will not be able to reserve enough energy to survive in winter.
A weak Japanese maple is more likely to suffer more serious problems once the cold arrives, such as insect infections, stunted growth, or it could die completely.
Luckily Todd Haiman, a landscaper and owner of Todd Haiman Landscape Design has stated preventing of powdery mildew is easy as all you need is baking soda.
Todd said: “I recommend first spraying with a diluted solution of baking soda and dishwashing soap. Mix one tablespoon of baking and one teaspoon of liquid soap (not detergent) to a gallon of water. Spray on plants every one to two weeks.”
Simple baking soda stops spores from being able to grow as it is a alkaline product, and fungus can only survive in a acidic or neutral environment.
Spraying Japanese maple leaves with a baking soda solution raises the pH level of the leaves which disrupts fungal growth and makes it difficult for the spores to spread.
How to use baking soda to prevent disease on a Japanese maple
All you need to do is mix one tablespoon of baking soda and one teaspoon of washing up liquid into a large watering can or sprayer filled with a gallon of water. Washing up liquid helps the baking soda stick to the leaves and not wash off when it rains.
If you want a stronger solution, it can also help to also add neem oil or potassium bicarbonate to the mixture as well. However, baking soda by itself is likely to be fine if you are just trying to prevent fungal growth.
Spray the solution on your Japanese maple during the day, preferably in the morning, to give it time to quickly dry off. Leaving moisture on the leaves at nighttime makes it more likely that fungal spores will spread.
Use the baking soda solution on your Japanese maple once every two weeks throughout autumn, and the tree should continue to grow its stunning foliage without any trouble.
