Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 

Pine needle blight pathogen gets weaker in New Zealand


6 November 2019


New Zealanders are used to hearing about plant diseases that arrive here and wreak havoc.

But for the first time, a New Zealand study has revealed that one introduced plant pathogen appears to have become weaker since it arrived here 50 years ago – possibly to make sure it doesn’t kill off its host.

The Dothistroma septosporum fungus, which infects pine trees, first appeared in New Zealand in the 1960s. It causes Dothistroma needle blight, one of the worst foliar diseases of pine trees worldwide. Infected trees lose their needles, grow more slowly, and can even die.

In other parts of the world D. septosporum can reproduce sexually, with two individuals mating to produce genetically different offspring. However, only one mating type exists in New Zealand – like having just males or just females – so the fungus reproduces asexually, effectively cloning itself.

Stringent New Zealand biosecurity regulations have helped to ensure that no more introductions of D. septosporum have occurred since the 1960s, so the current pathogen population is essentially a clone originating from that first introduction.

This provides a unique environment for studying its evolution, free from “confounders”, or complicating factors outside the study.

Lead author Prof Rosie Bradshaw, from the Bio-Protection Research Centre and based at Massey University’s Manawatū campus, said that while D. septosporum, like all fungi, reproduced rapidly, the pine trees they lived on were slow-growing and long-lived.

“If the fungus is too virulent, it will kill off its host trees and decrease its chances to move to other host trees, similar to people destroying their own houses,” she said.

In the study published in the scientific journal Microorganisms, researchers compared four isolates of D. septosporum collected in the 1960s with four isolates collected between 2006 and 2013, and two collected in 1991 and 1994. They then infected one-year-old Pinus radiata seedlings with the different isolates.

The fungal strains collected in the 1960s were much more virulent than the strains from the 1990s or 2000s.

“The four isolates collected in the 1960s produced higher levels of the known virulence factor, dothistromin, than any of the isolates collected from the 1990s onwards,” they wrote. “The effect of decade group on dothistromin levels was highly significant.”

This was opposite to what the researchers expected to see from isolates that had been in storage for so long.

Researchers also tested how the fungal strains reacted to copper (the main control method in commercial plantations), and found they had not developed resistance.

“Given that in New Zealand pine forests, trees are sprayed with copper fungicide sprays at most every two to three years, and only when certain thresholds of disease symptoms are exceeded, the selection pressure exerted by these antifungal compounds in the forest environment may be minimal compared to frequently sprayed agricultural crops,” co-author Lindsay Bulman, a science leader at Scion and the Bio-Protection Research Centre, said.

Prof Bradshaw said this was all good news for New Zealand foresters. “It means the disease is not as destructive here as it can be elsewhere, or as it was when it first arrived, and also suggests that copper spray is still an effective control.”

The finding also has significant global implications for forest health, suggesting the potential for incursions of some highly virulent clonal forest pathogens to become less virulent over time, regardless of human intervention, Prof Bradshaw said.

The implications for practical resistance breeding are that, in some situations, even low levels of resistance or tolerance might be sufficient to improve the long-term health of trees.

For the full study, see Reduced Virulence of an Introduced Forest Pathogen over 50 Years, DOI: 10.3390/microorganisms7100420

Ends


© Scoop Media

 
 
 
Business Headlines | Sci-Tech Headlines

 

Freight: New Report On Auckland Port Relocation

The Government has released a major new report on the options for relocating the Port of Auckland’s freight operations while deferring any decision on the issue. More>>

ALSO:

Chartered Accountants: COVID-19 Fails To Knock Kiwi Investor Confidence, But More Disclosure Wanted

Three months of COVID-19 lockdown and investment turmoil has done little to knock confidence in New Zealand capital markets and listed companies with overall investor sentiment very similar to 2019, an investor survey held in mid June shows. However, ... More>>

ALSO:

Taxation: Black-Market Tobacco Sidesteps $287 Million In Excise Tax

Year-on-year increases in consumption of illicit tobacco in New Zealand have seen illegal trade swell to 11.5% of the total market. If consumed legally, illicit products would have netted the Government $287 million in excise tax during 2019. Independent ... More>>

ALSO:

Energy Sector: Meridian Spilled Water To Hike Electricity Prices - Authority Ruling

The Electricity Authority has found that generator Meridian Energy manipulated the power market, costing consumers about $80 million. More>>

ALSO:

XE Data Update: RBNZ Official Cash Rate Decision

The RBNZ will keep the Official Cash Rate (OCR) at 0.25%. T he key points in the RBNZ statement are: RBNZ keeps the OCR unchanged at 0.25% Maintain the LSAP (large scale asset purchase) at NZD$60 billion. Committee prepared to use additional monetary ... More>>

ALSO:

Electricity: Kiwis Ignore Promise Of Cheaper Power

Electric Kiwi and Flick Electric Co are joint winners of Canstar Blue’s award for Most Satisfied Customers | Electricity Providers From putting on an extra layer – rather than turning on a heater – to turning off lights and choosing the energy-saving ... More>>

ALSO:

Electricity: Transmission Pricing For A Low Carbon Future

The Electricity Authority has decided on new guidelines for transmission pricing. James Stevenson-Wallace, Chief Executive of the Electricity Authority says the new guidelines will deliver significant benefits to consumers, through lower electricity ... More>>

ALSO:

NIWA: The Climate Record That Keeps Getting Broken

Among the multitude of New Zealand climate statistics there is one record that continues to be broken month after month. Since January 2017 there has not been one month that recorded a below average nationwide temperature, according to NIWA’s seven station ... More>>

ALSO:

Govt: Extended Loan Scheme Keeps Business Afloat

Small businesses are getting greater certainty about access to finance with an extension to the interest-free cashflow loan scheme to the end of the year. The Small Business Cashflow Loan Scheme has already been extended once, to 24 July. Revenue and Small ... More>>

ALSO:

Science: 2019 Prime Minister’s Science Prizes Announced

The 2019 Prime Minister’s Science Prizes have been announced in a digital livestream event today. The Prizes recognise the impact of science on New Zealanders’ lives, celebrate the achievements of current scientists and encourage scientists of the ... More>>

ALSO:


RNZ: Fuel, Alcohol Costs To Go Up From Today

The increase today in the taxes on fuel, road user charges and alcohol is being called a tone-deaf move. More>>

ALSO:

Stardome Observatory: Young Kiwi Astro-Photographer Shoots For The Stars

Matariki by Josh Kirkley. The stars are aligning for up-and-coming Auckland-based astro-photographer Josh Kirkley (Kāi Tahu). During lockdown, one of his images was picked up by NASA and shared on the space agency’s Instagram to its 59.2 million ... More>>


DCANZ: Time For EU To Commit To A Level Playing Field For Trade

The Dairy Companies Association of New Zealand (DCANZ) has welcomed New Zealand Trade Minister David Parker’s statement that it is unacceptable for New Zealand exporters to continue facing an ‘unlevel playing field’ in the EU. Details leaked ... More>>

ALSO:

Potatoes New Zealand: Protecting NZ Fries As Part Of PNZ Pandemic Recovery & Transformation Plan

Potatoes New Zealand has met with Minister Faafoi this week to discuss investigating the potential importation of heavily discounted frozen potato chips into New Zealand. With MBIE’s support we are undertaking an investigation to gather evidence of the ... More>>

ALSO:


New Zealand Government: Supporting Kiwi Businesses To Resolve Rent Disputes

The Government will legislate to ensure businesses that suffered as a result of the COVID-19 response will get help to resolve disputes over commercial rent issues, Justice Minister Andrew Little announced today. More>>

ALSO: