Three species in the Platanus genus are widely used as shade trees: P. occidentalis (sycamore, native to eastern US), P. racemosa (California sycamore, native to CA), and P. x acerifolia (a hybrid known as London plane). All three species are large maturing deciduous trees (100+ ft.) that tolerate urban growing conditions.
Culture for London Plane
All species tolerate a range of soil and pH conditions, though perform best in deep, slightly acidic soils with steady water supply. The two native species are most commonly found in nature along streambeds or on river plains. The foliage of all species is pubescent (hairy) and these hairs can become a skin or breathing irritant.
Concerns about London Plane
Sycamore anthracnose, cause of defoliation and branch dieback, is the most common problem, though London plane is less susceptible. Sycamore scale, leaf beetles, and defoliating caterpillars are also a concern. In the east, sycamore and London plane can be killed by ‘black stain’, a disease predominantly spread by human activity, and bacterial leaf scorch. In southern California, the Polyphagous shothole borer (PSB) attacks Platanus species and introduces a lethal fungus in the vascular system.
Management Practices for London Plane
Preventative foliar or injected treatments are available for anthracnose management. Scale insects and defoliating beetles and caterpillars can be treated as warranted when populations are detected. In southern CA, all sycamores should be treated with preventative bark beetle applications and PSB-attacked trees should also be treated with insecticide + fungicide injection. Leaf-scorch infected trees can be treated with antibiotic injection.