Japanese maple is one of the most common features in landscapes of the Pacific northwest and British Columbia. Many different varieties exist with variations in leaf color, leaf shape, growth habit, and bark appearance.
Culture for Japanese Maple
Performs best on well drained but moist organic soil, at slightly acidic pH. Variable by species, but often suffers from leaf margin scorching in full sun locations. Deep shade will cause colored foliage to revert back to green. Shallow roots will benefit from mulch to reduce soil temperature and moisture fluctuations.
Concerns about Japanese Maple
Verticillim wilt is the most common and lethal pathogen of this species. Phytophthora root rot and anthracnose foliar disease, defoliating caterpillars, and leaf feeding beetles are also common health issues. Like many maples, prone to formation of girdling roots which can slowly lead to dieback and mortality. Early season aphid infestations also occur. Armillaria is also known to cause decline and death of this species. Stressed plants may be attacked by ambrosia beetles.
Management Practices for Japanese Maple
There is no direct treatment for Verticillum wilt, but Potassium phosphite soil treatments will help prevent infection and slow decline in infected plants. Expose root collars and inspect for / remove any girdling roots. Mature specimen should be pruned so that the unique branching architecture is visible. Mulch and add organic matter when soil OM is less than 5%. Treat preventatively against ambrosia beetles when plants are stressed.