but is costly to administer and restricted to known plants. Other diseases to which B. brownii is vulnerable include the parasitic fungus Armillaria luteobubalina and the aerial canker fungus Zythiostroma. Fire regime Because B. brownii releases its seed in response to bushfire, it is important that fires occur at intervals that allow the plants to generate plenty of viable seed. The optimum fire interval is around 18 years. If fire occurs too frequently, plants are burned before reaching maturity or before they have produced sufficient seed to ensure regeneration of the population. This may cause populations to decline, or even local extinction. Too-infrequent fire also causes population decline, as more plants die of natural attrition without releasing their seed, resulting in seed wastage. Ex situ conservation measures Because of the difficulty of conserving B. brownii in its present disease-exposed locations, it is an especially suitable candidate for ex situ conservation measures, such as the cold-storage of seed, and the translocation of plants to disease-free locations. Seed of B. brownii has been collected by Western Australia's Threatened Flora Seed Centre, and placed in cold-storage both in Perth and at Kew's Millennium Seed Bank. This includes seed collected from populations that have since become extinct. In 2008, some of this seed was germinated, and seedlings were planted at a location near Albany. Genetic analysis of the seedlings revealed some genetic diversity that was not present in any extant population. The conservation of these seeds had thus preserved some of the species' genetic diversity that would otherwise have been lost through population extinction, providing a powerful example of the importance of seed banking to conservation efforts. A seed orchard was planted in 2007, and by 2010 this had yielded over 400 disease-free, healthy plants, some of which had grown more than three times the rate of those in the wild. A 2007 seedling flowered for the first time at Wakehurst Place in February 2011. Cultivation With large metallic red inflorescences and attractive feathery leaves that are perhaps the softest of all Banksia species, B. brownii is highly valued by Australia's horticultural and cut flower industries. Seeds and plants are readily available in Australian nurseries, and it is widely cultivated in areas not exposed to dieback. Seeds do not require any treatment, and take 20 to 50 days to germinate. The plant prefers a sheltered position in soil with good drainage, and must be