Maple Society Chairman On 3 Issues That Are Common With Acer Plants
Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.
Reviewed By DAN ORI
Dan has over 27 years’ under his belt caring for plants and gardens. Working as a Horticultural Instructor and Consultant, he draws on a diverse range of experience that includes working as a Head Gardener, Tree Surgeon, Garden Centre Trouble Shooter, and writer of academic papers. Dan has a Level 3 Diploma in Horticulture and is currently a candidate for the RHS’s most prestigious award – The Master of Horticulture.
Contributions From AGUSTIN COELLO-VERA
Agustin is the Chairman of The Maple Society, a society founded in the UK in 1990 that has now turned into an international community. Agustin has 30 years of experience growing maples, with about 700 taxons planted in his forest garden. He frequently shares his knowledge with other garden societies and on gardening podcasts.
Whether you are growing them in the soil in your garden, or have a smaller type in a pot, you should find Acers a relatively hassle-free addition to your space.
However, as always in gardening, there are times when things don’t go entirely according to plan.
Some of the most common growing problems and issues you may encounter when growing around maples are:
- Environmental Issues – which can cause leaf scorch.
- Diseases – such as verticillium wilt and other fungal issues.
- Pest Problems – such as aphids and horse chestnut scale.
We’ll take a look at these most common issues and problems below, so read on to find out a little more.
1) Environmental Issues
Many of the issues which can arise when growing maples can be prevented by understanding the growing needs of these plants and placing them in the right location.
Acers typically prefer a site in full sun or partial shade, in a sheltered spot out of drying winds.
The soil or growing medium must remain moist, but should also be free-draining since waterlogging can be a problem.
They tend to prefer acidic or neutral soil but can grow very well in all but the most alkaline of soil environments and are far less fussy about soil pH than many people imagine.
Leaf Scorch
The popular Japanese maples (Acer palmatum) can be prone to leaf scorch.
In fact, this is the most common issue encountered when growing these plants in the UK.1Acer: leaf scorch. (n.d.). Royal Horticultural Society. Retrieved March 9, 2023, from https://www.rhs.org.uk/problems/acer-leaf-scorch
If you are growing a type with heavily dissected leaves then you are particularly likely to encounter this problem.
Leaf scorch is when leaves turn brown on the tips and may curl or shrivel up.
Brown leaves on Acers are commonly caused by environmental stresses, such as frosts, drying winds, waterlogging, drought or intense sun.
Leaf scorch occurs whenever leaves lose moisture more quickly than water can be taken up by the roots of the plant.
Fortunately, though it can look unsightly, the damage to the leaves is rarely long term and most Acers will recover as conditions improve.
2) Verticillium Wilt
“The most common problems maple enthusiasts may encounter are Pseudomonas bacterial infection and vascular diseases produced by the Fusarium and Verticillium fungi,” explains Agustin Coello-Vera, Chairman of The Maple Society.
Verticillium wilt is a fungal disease borne in the soil which can impact a range of plants – maples included.
This disease can cause maple leaves to yellow, wilt and die back.
Though this problem can arise throughout the year, it is most likely to strike during hot weather in summer.
The fungal issue begins in the roots, and as the problem spreads, brown or black streaks can be seen in woody tissue under the bark and branch dieback may occasionally occur.
Good garden hygiene is key to preventing the spread of this soil-borne disease.
Unfortunately, if this problem is present in the soil, an infection can recur.
Acers are one of the plants most susceptible to this, so if you have an outbreak, it would be better to select more resistant options for your garden.
There are also some other fungal issues that can cause problems for Acers, especially when the environmental growing conditions leave something to be desired.
“If your leaves are turning yellow or are off colour and it is not autumn, this could be due to disease or fungal issues like Verticillium wilt.
“Equally the leaf discolouration can be due to pest attack, exposure to cold, conditions too dry, conditions too wet, too much sun, or it could also be something called Chlorosis (a nutrient deficiency),” says Dan Ori.
Dan explains that Chlorosis can be common in Japanese maples grown in alkaline conditions.
“To combat Chlorosis in Acers caused by high pH conditions, repot or top-dress with ericaceous compost and use rainwater if possible.”
3) Pest Problems
Finally, though these are not usually such major problems for maple growers, your Acer may also be plagued by pests.
Aphids & Horse Chestnut Scale
Aphids, for example, are one sap-sucking species that can be attracted to Acers and reduce a plant in vigour a little if the infestation is severe.
Horse chestnut scale is another pest that can be encountered when growing Acer in a garden.
Luckily, both of these pests rarely become extreme problems and by adopting the principles and practices of integrated pest management and organic gardening approaches, it is usually possible to keep an ecosystem in balance.
Remember, you need to have some pests in your garden, so the goal is not to eradicate them entirely but to keep their populations in control.
The pests’ presence is required for healthy populations of the beneficial predatory wildlife that helps to keep their numbers down.
