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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

26 Aug 2024

Celebrating a pest-free Port

KVH will be at the Port of Tauranga over the coming weeks, highlighting frontline efforts to ensure a pest-free environment. There are many enthusiastic people who work on and around the Port who know biosecurity is a critical issue, affecting everyone in some way. With hundreds of people operating on the frontline of the Port community daily, we have lots of eyes constantly on the lookout for unwanted pests. The Port deals with millions of tonnes of cargo each year, and around 100 cruise ships over every summer, so we all need to be ready, vigilant, and watchful. Biosecurity matters at Ports because it is also a significant business risk. The frontline staff we’ll be meeting with and talking to - such as stevedores, and straddle/crane drivers - are the best placed to initially notice and report anything unusual. Our key message is if something happens, there will be a cost to you, your job, or your business, and you need to know what you can do to stop it. As the organisation responsible for leading biosecurity preparedness on behalf of the kiwifruit industry, KVH partners in this initiative alongside the Port of Tauranga and the local Biosecurity New Zealand team. Other activities with the Port community include staff from Biosecurity New Zealand visiting transitional facilities across the Bay of Plenty to share up-to-date information about managing risk and distribute useful collateral such as the ever popular 12 most unwanted pests calendar produced by the partnership, and both Biosecurity New Zealand and KVH taking part in pre-cruise season briefing sessions for the Port’s security staff. You can see online versions of the resources we’ll distribute this year here: Annual pest calendar September 2024 - August 2025"Most unwanted pests” playing cardsSpot it, snap it, report it frontline lunch bags

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26 Aug 2024

Biosecurity best practice

What are the top five things you need to do if you are part of the kiwifruit growing community in New Zealand, to ensure you are following biosecurity best practice and managing risk? We’ve created a video – it’s only two minutes long – running through all five easy to follow steps. It’s specifically designed to help with training, and for use at places like reception areas and events so if you’d like a copy let us know. Thank you to the team at Trevelyan’s for the support in producing the video, including the sites and wonderful talent! Watch it here.

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26 Aug 2024

2024 AGM results

The KVH Annual General Meeting (AGM) was held Wednesday 21 August, and we thank all those who were able to attend, and those who voted. All Resolutions were passed at the AGM: That the minutes of the 2023 AGM be approved. That the Chairman and Chief Executive’s reports be approved. That the financial report for the 12 months ending 31 March 2024 be approved. Approval of the Biosecurity (Readiness and Response) and the Biosecurity (Kiwifruit National Pathway Management Plan) levy rates. For the year ending 31 March 2026 the Biosecurity (Readiness and Response) levy continues at the rate of eight tenths of a cent – 0.8c - per tray equivalent on all commercial varieties of kiwifruit except Actinidia arguta, exported to all markets other than Australia, and the Biosecurity (Kiwifruit National Pathway Management Plan) levy continues at the rate of six tenths of a cent - 0.6c - per tray. That the budget for 2025/26 be approved. That Directors fees increase by 3% for the 2024/25 financial year. That BDO be reappointed as the auditor for the 2024/25 financial year. That Liarna White is re-elected as a Grower Director, and Fiona Carrick is re-elected as an Independent Director, both for a term of three years. If you have any questions about the results, please contact KVH or speak to a KVH Director. All AGM documents, including Resolutions, financial statements and budget information are available to reference on the KVH website.

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