Importing endangered Engelmann oaks during a pandemic Jo Brennan, Horticulturist (Horticulture), Royal Botanic Gardens Victoria Melbourne Gardens Lying in trays of seed-raising mix in the Royal Botanic Gardens Victoria (RBGV) Melbourne Gardens nursery are 99 unassuming Quercus engelmannii acorns. They are special, however, because they are an endangered species, and it has taken five months of collaboration with the Los Angeles County Arboretum and Botanic Garden (the arboretum) and the Department of Agriculture, Water and Environment (DAWE) to get them here. More excitingly, some have survived transit and prescribed biosecurity treatments and are starting to germinate. All going well, they will be ready to plant in our Oak and North American Dryland Collections in June.
Importation challenges
Quercus engelmannii radicle. Credit: Royal Botanic Gardens Victoria
The oak collection within the RBGV dates from around 1862 and features numerous old and venerable specimens, many of which would have been brought into Australia as acorns stowed in the pockets or suitcases of avid collectors. Others no doubt made their way through the postal service without impediment. More recently, Australia’s stringent biosecurity laws have imposed strict controls on the importation of seed in general, and with good reason – who wants to accidentally introduce Sudden Oak Death (Phytophthora ramorum) or Khapra Beetle (Trogoderma granarium) to our shores? This, however, makes obtaining wild-collected material from overseas far more complicated and time consuming. Importing acorns is even more complex – they are desiccation-sensitive, so minimising storage and transit time is crucial. They must also be fumigated with phosphine or undergo cold treatment at −18 ˚C, both of which can add between 10 days and three weeks to their journey. Given that Quercus are recalcitrant species and generally do not survive freezing below −10 ˚C, the latter is a high-risk option. The effect of phosphine gas on acorns is not well documented but has also raised concerns. Add in potential disruptions to freight services, staff absences due to COVID-19 and the busy holiday season (including Thanksgiving and Christmas) and you would be forgiven for wondering why anyone would attempt to bring in acorns during a pandemic!
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THE BOTANIC GARDENer | ISS 58 Winter 2022
