bought a new house with a pittosporum hedge that is dropping its
leaves badly. It is about 1.5m tall and has black patches on the
lower leaves. There are white things about 2mm long that look like
scale stuck on the branches. Any advice on giving it a boost?
does sound as if scale is the culprit. The black patches on the
lower leaves will be sooty mould growing on the sweet honeydew excretions
dripping from the scale above.
Pittosporums aren't particularly
susceptible to scale but if the hedge is weakened by some other
factor, such as drought or lack of nutrients, they could become
a problem. I'd be inclined to give the hedge a good trim, cutting
back a good two thirds of the leafy growth. This should remove a
lot of the scale as they prefer to feed from the soft young stems
rather than the tough woody ones. Then spray the remaining growth
thoroughly with a relatively user-friendly insecticide such as Clear
White Oil or Conqueror Oil. Spray in cloudy weather rather than
in bright sunlight, or in the evening, to avoid the risk of scorching
the remaining leaves. Apply a dressing of general fertiliser and
give the occasional deep watering during dry periods to encourage
Gardener, Issue 138, 2004, Page 27
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.