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Kiwifruit's most unwanted

Kiwifruit's most unwanted

There are eight organisms identified as the biggest biosecurity threat to New Zealand's kiwifruit industry.

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 Kiwifruit's most unwanted

Kiwifruit's most unwanted

Invasive Phytophthora

Phytophthora is present around the world, including New Zealand, in a wide range of hosts. There are over 100 known species of Phytophthora, with thoughts there could be up to 500 more yet to be identified.

There are many reports of different Phytophthora damaging kiwifruit vines in different regions globally, such as P.drechsleri, which has caused significant impacts to the kiwifruit industry in Korea.

It is considered highly likely that under certain conditions (i.e. wet soils) kiwifruit would be susceptible to several Phytophthora species. Predicting which species will impact which cultivars, and under what conditions, is difficult if not impossible to predict. Because of this, KVH is undertaking readiness planning and research for invasive Phytophthora species as a whole, as opposed to focusing on one specific species.

Threat Levels
Likelihood of entry
Medium
Likelihood of establishment
Medium
Production impacts
High
Market access impacts
Very Low

Pest ranking based on the KVH risk matrix

View risk matrix

The biosecurity threat of Phytophthora to the New Zealand kiwifruit industry is largely unknown. It could come from the introduction of a new Phytophthora species, or from a species already here that may not yet have been exposed to kiwifruit.

Management practices, cultivar susceptibility and the environment may also play key roles in any future outbreaks. Phytophthora are Oomycetes (or water moulds), so wet, soggy soils are an ideal environment for them to thrive. As such, low-lying land, poorly drained orchards and additional irrigation are more susceptible to infection.

Symptoms

One of the difficulties with detecting Phytophthora disease symptoms is that they are variable and often are not distinct from those resulting from other plant pathogens (such as Armillaria root rot which can sometimes be misdiagnosed as Phytophthora root rot).

The other difficulty with Phytophthora symptom detection arises from asymptomatic plants, where the pathogen can lay dormant for long periods until conditions change and symptoms are expressed. There are many types of symptoms associated with Phytophthora species that may occur singly or in combination.

Phytophthora usually infects kiwifruit vines from root wounds or the root tips early in spring. During the warmer summer months, vines may rapidly decline or alternatively show gradual decline in productivity over several seasons. Symptoms include reduced shoot growth; small, chlorotic leaves; and an open canopy. Vines with the graft union below ground level or mechanically wounded trees are easily infected. Infected root and root crowns commonly show a red brown rot that is easily observed when cutting into the outer layer of tissue. Generally, there is observable margin where healthy, white tissue meets infected, discoloured tissue. Infected roots become dark and feeder roots are often black, decayed and few in number (see image below).


phytophthora photos and videos

Infected roots become dark and feeder roots are often black, decayed and few in number.

phytophthora reference material

  • Kiwifruit Phytophthora survey on New Zealand orchards - KVH, Zespri and Plant & Food Research are working together on a survey of Phytophthora pathogens in kiwifruit orchards throughout New Zealand. This project will support New Zealand’s biosecurity by better understanding our current baseline of Phytophthora species associated with kiwifruit.
  • Potential impacts on kiwifruit and kiwiberry - a literature review presenting detailed information on the potential threat posed by Phytophthora, and three case studies highlighting principles of spread, management and control.

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LATEST NEWS

05 Jun 2025

Strengthening connections between industry and Biosecurity New Zealand

Recently KVH travelled to Pukekohe and linked with the Punchbowl team to host a workshop for members of Biosecurity New Zealand (BNZ), to connect, network, and share an understanding of the industry’s infrastructure and past and potential forward impacts of biosecurity responses. The visiting group included principal scientists from New Zealand’s Plant Health and Environmental Laboratory (PHEL) and Incursion Investigation Plant Health teams; BNZ response managers, including members involved in the fruit fly responses earlier this this year and who also played a role through the Psa response; and relationship managers who hold a vital role in fostering ongoing connectivity between BNZ and industry in the readiness and response space. Rob Craig shared the history of Punchbowl and provided an insightful history of kiwifruit industry impacts related to economic and market challenges, and business impacts following the Psa incursion. He noted the heightened industry awareness of the very real implications of a fruit fly incursion, especially for businesses close to ports and airports. Rob also emphasised the willingness to support the industry KiwiNet network which coordinates the deployment of kiwifruit industry personnel into biosecurity responses. KVH highlighted the value, expansion, regionality and seasonality of the kiwifruit industry and reflected on industry’s keen awareness of the potential impacts of our most unwanted pest threats. The unusual symptoms surveillance programme was described and clearly showed the connectivity and support of the PHEL team in this space. Lalith Kumarasinghe, manager of the PHEL lab described the wide-ranging analytical roles of his team which provide ongoing support to New Zealand’s biosecurity processes. The visit wrapped up with a guided tour of the Punchbowl pack-house and cool stores, and an opportunity to get out in the sunshine and under a kiwifruit canopy to hear more about the growing side of our industry. This opportunity for BNZ/ PHEL and the kiwifruit industry/ KVH to connect was considered immensely valuable by all parties. KVH would like to sincerely thank the visitors for taking time away from their busy schedules, and the Punchbowl team for warmly opening their doors to share the industry story.

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05 Jun 2025

Biosecurity top of agribusiness priority list again

In the 2025 Agribusiness Leaders Priority Survey, biosecurity was once again ranked top (for the 16th year in a row) by leaders from across the food and fibre sector, who provided insights into the importance of peacetime planning, and putting the time and effort into regularly using and testing systems before a biosecurity crisis hits so that we can optimise response outcomes. This is a key priority for KVH, and we’ve got another response exercise coming up later in the year that we’ll share in more detail in upcoming Bulletins. The importance of good communication about biosecurity risks and response procedures was another noted insight and point made by leaders. Engagement with growers and those managing orchards is something the KVH team in sharply focused on – we do a huge amount of work in this space already and we’re ramping it up. We’ll be working with growers, post-harvest and orchard management teams (via Zespri and GAP audits, or sometimes directly) to provide everything needed for those managing orchards to meet regulatory requirements under the National Kiwifruit Pathway Management Plan, including having an on-orchard biosecurity plan. As the KPMG report states, “most people (in the sector and beyond) don’t have deep knowledge of biosecurity risks and response procedures” – this makes it critical that as a dedicated biosecurity organisation we provide helpful, concise, timely communication and tools, so people are clear on what they need to do and why. Biosecurity plans can be created online via the KVH website here. View the biosecurity page from the report here, or see the full report on the KPMG website here.

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05 Jun 2025

“It only takes one” goes wider

New Zealand’s border biosecurity campaign is reaching further afield, with targeted ads now running in the UK and soon in the US. The campaign reminds travellers that it only takes one risk item to do serious harm to New Zealand. It aims to get travellers thinking about biosecurity before they even pack – especially high-risk items for our industry like soiled boots, and food. In the UK, digital ads are now playing in the major airports of London, Manchester, and Birmingham, as well as online for people searching for travel to New Zealand. Advertising in the US will begin shortly and the campaign will then expand to China and India. Know someone visiting from overseas or visiting our orchards? KVH also has a specially designed poster for best biosecurity practice and what to expect at border control.

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