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Norfolk Island Flora & Fauna Society

Phytophthora cinnamomi

Updated on date by author

Phytophthora is a group of microscopic soil-borne pathogens that can cause dieback and root rot in a range of different plants. Different species of Phytophthora can cause dieback and root rot in different plants. While most species of Phytophthora affect a limited number of plants, Phytophthora cinnamomi can affect a broad range of plant species.

Phytophthora are not visible to the human eye and don’t always cause symptoms. A plant may appear healthy for a long time and suddenly exhibit symptoms when conditions change, for example after an increase in humidity. This means that it can be challenging to know whether the pathogen is present or not.

There is debate in scientific circles as to the date of its arrival in Australia. The mainstream view is that the devastation caused to the jarrah forests in Western Australia and the heathlands along the east coast, particularly the grass-trees (Xanthorrhoea) and proteaceous species, points to a post-1788 introduction.

Is Phytophthora cinnamomi present on the Island?

Two snippets of evidence suggest “Yes”. A study in the 1970s reported finding the organism (Benson 1980), but the results cannot be confirmed.

A multidisciplinary plant health survey in 2012-14 covered introduced plants, invertebrate pests of plants and animals, plant pathogens, pests and diseases of bees and diseases and parasites of domestic animals. In total, 1747 species were recorded across all organism groups. Phytophthora cinnamomi was not specifically targeted, but a sample collected to test for another pathogen was found to contain Phytophthora, though it was not identified to species level at the time. The sample was re-examined in 2019 and identified as Phytophthora cinnamomi.

The two records were not considered to be sufficiently strong evidence on their own to make a determination on the status of this pest. For this reason, Australian Government scientists visited the Island in February/March 2021 to collect more samples.The survey team collected 67 samples and processed them on Island before sending to Sydney for diagnostics.

Plant pathologist Harshitsinh Vala germinates seed of lupin (very sensitive to P.c.) to aid in detection.

Scientists Elizabeth McCrudden and Sandy Perkins take soil samples.

The visiting scientists advised that “The success of this survey would not have been possible without the support and guidance from the Norfolk Island Biosecurity staff and the Norfolk Island community, who have allowed the team generous access to homes and properties to collect samples.”

Importation of aggregate

Importation of aggregate for the Norfolk Island Airport Pavement Repair and Resurfacing project raised some questions about the status of Phytophthora on the Island. It was decided to treat Norfolk Island as if it were free from P. cinnamomi when imposing conditions for the aggregate importation. This decision was made to afford the Island the highest level of biosecurity protection possible until more complete information could be obtained. The 2021 survey of samples collected on a grid across the Island is intended to fill the gaps in knowledge.

 

Posted in Introduced Flora |

Myrtle Rust on Australia’s islands

Updated on date by author

Myrtle Rust is a fungal pest that slipped through Australia’s weak biosecurity defences. In 2017 Australia’s Invasive Species Council published a note about its arrival on Norfolk Island and on 17 May 2017 issued a press release:

“Over the past six months myrtle rust has been detected on both Lord Howe Island and Norfolk Island. Australian authorities have responded poorly to both outbreaks.

On Lord Howe Island, Lord Howe Island Board staff swung quickly into action to try to eradicate infected plants but received little support from the NSW government’s primary industry and environment departments beyond advice. Lord Howe Island Board staff had to rely on their own limited resources because myrtle rust is now considered “endemic” in NSW.

On a recent visit to Norfolk Island our CEO Andrew Cox discovered that myrtle rust had been found on planted rose apples (Syzygium jambos) six months ago. No public information about the detection has been released, and the federal agriculture department is still determining a response. The new Norfolk Island Regional Council seemed unaware of the arrival. Thankfully there are no native myrtles on the island.

Myrtle rust outbreaks on these two iconic islands should have been prioritised at state and federal levels. Once established, the rust could spread to other offshore islands and possibly to mainland New Zealand. Last month myrtle rust was found at Raoul Island, about 1000 km northeast of New Zealand and a similar distance east of Norfolk Island.”

Posted in Invasive Species |

Norfolk Island Conservation Volunteers

Posted on date by author

Norfolk Island Conservation Volunteers (NICV) was formed in July 2020 under the auspices of the Norfolk Island Flora & Fauna Society Inc., and with the support of Norfolk Island Regional Council and Norfolk Island National Park.

 

The Coral Berry Crusade

The first NICV project, and the only project to date, has been tackling a heavy infestation of the very invasive coral berry (Rivina humilis) in 100 Acres Reserve. This South American native had established itself in the reserve over many years, and had become the dominant ground cover. Quick-growing and with numerous very hardy seeds produced per plant, its dominance was affecting other native ground cover, and also the slower growing seedlings of native trees and bushes, out-competing them for space, light, water and nutrients.

In its first year, NICV was able to make one full sweep through the reserve and was well into its second or in some spots, third sweep, aiming to catch the coral berry before fruiting  and thus progressively exhaust the seed bank. This strategy has been extremely successful so far, with coral berry now replaced by a delicate native herb, Parietaria debilis, as the dominant ground cover. Prior to this, P. debilis had become very scarce in the reserve.

In addition to coral berry, NICV has been pulling up other known weeds as encountered. These have included African boxthorn, silky oak, lantana, tomato, guava, ochna, cape gooseberry, black olive, Hawaiian holly, Morning Glory vine, Madeira vine, chickweed and milkweed.

As the work on coral berry now appears to be approaching maintenance phase, NICV is discussing options of extending into other reserves and the National Park, or remaining in 100 Acres but becoming more systematic in tackling the other weed species found there.

 

Posted in Get Involved, Invasive Species |

Kentia Palm

Updated on date by author

Williams, Kevin. 2007. Seed to Elegance: Kentia Palms of Norfolk Island, South Pacific. Norfolk Island: Studio Monarch. Purchase via https://kentiapalmchronicles.wordpress.com/.

 

The palms that are common around Norfolk Island are the Kentias, Howea belmoreana and Howea forsteriana, endemic to Lord Howe Island but not Norfolk, which has its own endemic palm Rhopalostylis baueri.

School teacher TB Wilson of Lord Howe Island deposited a quantity of Kentia Palm seeds at Norfolk Island in 1881. Palm seeds were exported from Lord Howe Island to England from about 1898 to meet demand from the greenhouse trade. The palm was found to flourish indoors and became a favourite houseplant of the European nobility and reportedly a particular favourite of Queen Victoria. Williams reports that in 1899 some 2 million seeds were auctioned in London.

From the early 1900s, supply was diversified to include Norfolk. Pitcairn descendant Ivens ‘Pullis’ Nobbs is credited with pioneering the Kentia industry, after his return from World War II.

Williams describes the Kentia as “the most common ornamental palm species in the world” because it requires little maintenance or light. Norfolk still supplies 90% or more of all Kentia products sold via the international flower auction house in Aalsmeer, The Netherlands.

Posted in Introduced Flora |