Xerochrysum Bracteatum - Ecology

Ecology

The brightly coloured bracts act as petals to attract insects such as hoverflies, native bees and small beetles that pollinate the florets. Grasshoppers also visit the flower heads. The caterpillars of Tebenna micalis have been recorded on this species, as have those of the Australian painted lady (Vanessa kershawi). The tiny fruits are dispersed by wind, and germinate and grow after fire or on disturbed ground.

Experimentation at the Waite Institute of the University of Adelaide showed that flower production was related to increasing day length, and in general, plants produced the most flowers from December to March. Varying planting times or artificially changing light levels might be ways to increase production of flowers outside these months.

The water mould (oomycete) Bremia lactucae has infected commercial crops in Italy and California. In 2002 on the Ligurian coast, widespread infection of several cultivars, most severely 'Florabella Pink' and to a lesser extent 'Florabella Gold' and 'Florabella White', resulted in leaf blistering and the development of chlorotic lesions on the leaves, and white patches on the undersides, particularly in areas of poor ventilation. There was an outbreak of downy mildew in a cultivated crop of Xerochrysum bracteatum in San Mateo County, California in 2006, in which the leaves developed large chlorotic lesions. A Phytoplasma infection damaged X. bracteatum crops in the Czech Republic between 1994 and 2001, causing poor growth, bronzing of foliage and malformation of flower heads. Genetically, the pathogen was indistinguishable from the agent of aster yellows. The root-knot nematode (Meloidogyne incognita) attacks and forms galls on the roots, which leads to the morbidity or death of the plant.