There are several reports of damage to flowers in the
Bundaberg region from a pest previously unknown to macadamia, Citrus Blossom
Bug (CBB) Austropeplus sp. Well known as a sucking pest impacting
flowers and small fruitlets in avocado and other flowering fruit crops, CBB has
not been a problem in macadamia up until this season. Growers and pest scouts
are being asked to be on the look out and document any sightings and damage.
Damage
Preliminary information suggests that high populations of CBB feeding on
early-stage flowers cause flowers appears as wet lesions on flower buds which
darken to brown or black over time and shrivel. This feeding damage may lead to
excessive flower loss and significant yield impact.
Identification
Adult CBB range in size from 3.5 - 5mm. Adult body colour is generally
yellow-green with dark brown-black colouration on the back and wings. Females
tend to be brighter in colour than males, though both have patches of yellow
and red on the wings. Adults can be reliably identified in the orchard by the
bright yellow-green heart or V-shape mark on the back and the presence of fine
gold hairs on the wings.
Nymphs are green and range from 1 - 4mm in size, depending on the stage.
Nymphs can be identified by the red and white banding on the antennae, the red
markings that extend over the eyes and a large red spot in the middle of the
back in later instars. Nymphs have appeared early in the macadamia flowering
period between bud break and full elongation.
Management
Start monitoring weekly for CBB adults and nymphs after bud break by
direct observation. CBB seem to be most active on developing flower buds during
the morning and in higher numbers on the sunny-side of rows. CBB has appeared
in trees on the boundary and adjacent rows early in the season first, before
moving into the rest of the orchard. CBB nymphs can be difficult to spot but
seem to prefer feeding in trees with dense amounts of racemes. Inform your pest
consultant if you spot any CBB or typical damage and they will assist you with
a management plan.
Image credit: Rohan Orford (images 1-4), Eddy Dunn (images 5-9).