Archive for the ‘Plant Pathogens’ Category


Fungus induces abnormal growth of cocoa trees and then feeds on dead tissue

Researchers have discovered that infection occurs in two stages. The fungus first releases cytokinin and makes the tree produce lignin, its favorite food. In the second, the fungus consumes the lignin.Peer-Reviewed Publication


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Micro-Tom tomatoes infected by Moniliophthora perniciosa

The action mechanism of the fungus Moniliophthora perniciosa, which causes witch’s broom disease in cocoa trees, with major losses for Brazilian producers, is being increasingly elucidated. In an article published in the Journal of Experimental Botany, researchers at the University of São Paulo’s Center for Nuclear Energy in Agriculture (CENA-USP) in Brazil report that the pathogen makes trees grow excessively, draining their energy, and that when they die, it colonizes dead cells and feeds on the accumulated lignin.

Previous research by the same group showed that the fungus synthesizes cytokinin, which alters the plant’s hormone balance and leads to excessive growth of infected tissue, competing with fruit production and root growth, and exhausting the plant via a mechanism similar to cancer (more at: agencia.fapesp.br/36824). 

Now the group has discovered that infection occurs in two stages. The fungus first releases cytokinin and makes the tree produce lignin, its favorite food. In the second, the fungus consumes the lignin.

“There are two kinds of plant pathogen: biotrophic, feeding on living tissue, and necrotrophic, feeding on dead tissue. There’s also a hybrid class called hemibiotrophic, which initially infects living cells and then parasitizes dead cells at a later stage. M. perniciosa belongs to this hybrid class,” said agricultural engineer Antônio Figueira, a professor at CENA-USP and principal investigator for the research project.

According to Figueira, the fungus’s biotrophic phase is much longer than normal, lasting 30-45 days. During this phase, spores germinate and give rise to a specific, thicker and more irregular mycelium, which grows between the host cells without entering them.

“There’s little tissue colonization, so it’s hard to observe fungal hyphae in infected plants under a microscope,” he said. “On the other hand, the host’s tissue displays spectacular symptoms of disease, with overbudding and thickened branches. In other words, the fungus causes significant symptoms even though its density in tissue is low.”

The latest study by the researchers demonstrated that this hypergrowth drains the host plant’s energy, reducing the number and weight of its fruit as well as its root biomass. All this happens without an increase in fungal mycelium production.

“Tissue death occurs in the next phase of the disease when mycelium enters the cells and grows significantly. This mycelium is morphologically distinct, thin and linear, and colonizes all the dead tissue. After a time, mushroom production begins,” Figueira said.

Researchers had long wondered why the fungus appears not to benefit from colonizing the plant and causing so many symptoms. The new study provides answers.

“We discovered that during the initial phase, the plant hormone cytokinin released by the fungus makes the infected plant produce a great deal of vascular tissue so that secondary cell walls accumulate lignin, on which the fungus feeds after the plant’s tissue is dead,” he explained.

The species closest to M. perniciosa are all saprotrophic, meaning they feed on dead tissue and other organic detritus. The fungus that causes witch’s broom has apparently evolved to be capable of infecting living tissue, modifying its metabolism to promote the synthesis of lignin, its favorite food, and establishing a foothold in the plant before tissue death occurs. “This gives M. perniciosa a clear advantage over competing fungi,” Figueira said.

Cocoa crisis

Witch’s broom disease was first described in 1919, but it was apparently confined to Amazonia in the North region of Brazil until the late 1980s when it spread to southern Bahia in the Northeast region. Brazil was then the second-largest cocoa grower, producing more than 400,000 metric tons per year. As a result of the disease, annual harvests had fallen to some 100,000 tons by 2000.

The industry is slowly recovering, but Bahia is no longer Brazil’s foremost cocoa-growing state, having fallen behind Pará. In 2020 the national crop was still only 250,000 tons, ranking seventh in the world. The latest scientific research is highly promising for the development of novel crop management techniques.

The study was supported by FAPESP via seven projects (16/10498-413/04309-616/10524-517/17000-415/00060-918/18711-4, and 19/12188-0).


About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.


Journal of Experimental Botany




Infection by Moniliophthora perniciosa reprograms tomato Micro-Tom physiology, establishes a sink, and increases secondary cell wall synthesis



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News reporting

‘Nose Knows Scouting’ uses trained dogs to sniff out Potato Virus Y

A North Dakota potato breeder brings in a speaker from Wyoming who has trained a dog to detect potato virus diseases using their nose.

A woman takes a black Labrador dog to smell bags of potato tubers on a driveway, as researchers look on.
Andrea Parish of Dayton, Wyoming, sniffs bags of potato seed tubers for disease in the North Dakota State University potato breeding program, as NDSU potato breeder Asunta “Susie” Thompson and technician Kelly Peppel look on. Photo taken May 17, 2022, at Fargo, North Dakota.

By Mikkel Pates

May 23, 2022 05:30 AM


 We are part of The Trust Project.

FARGO, N.D. — Good news: the newest high-tech tool for diagnosing crop disease is also man’s best friend — a friendly dog….

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Crop scouting app for faster data collection

These days – whether it’s due to covid or other reasons – growers often have less staff at their farms. But when under pressure to deliver more with less, digitizing and expediating manual tasks is key to optimizing labor.

The FarmRoad mobile app aims to streamline crop scouting and crop registration so your team can work faster without pens or clipboards. Record crop measurements, pest numbers, and disease outbreaks using your phone. Upload photos, type comments then instantly share with your team so you can act fast to address the issues.

Speed up and simplify crop data capture
The FarmRoad mobile app provides a simple solution to streamlining crop scouting tasks. The app works on both phones and tablets and collects data on:

  • Pests
  • Beneficial insects
  • Pest traps
  • Plant diseases
  • Plant disorders

Record pest types and infestation locations
Understanding pest pressure relies on comprehensive monitoring of different types of pests (e.g., whitefly, thrips) and their numbers. Use the FarmRoad mobile app to log the location of infestations and record pest types and their prevalence to evaluate the effectiveness of your beneficial insects. 

Collect pest trap data faster
Insect traps are essential to directly reduce the populations of the insects and other anthropods that affect your crop. Using traps as part of your pest management reduces the need for pesticides. Use the FarmRoad mobile app to collect pest trap data faster.

Document plant disease threats
Managing plant disease outbreaks keeps every grower on their toes. Monitoring environmental conditions and pathogen transmission at your farm enables you to track outbreaks to keep them under control. Use the FarmRoad mobile app to upload photos, dates and write comments to keep your team updated on disease occurrences in your greenhouse.

Faster identification and communication of potential crop problems
Crop scouting is necessary to keep plants healthy and to prevent pests or pathogens from reaching dangerous levels. Arm your team of scouts with the app to record crop threats at precise locations. Staff can upload photos, comment, and share immediately so swift remedial action can be taken.

Visualize and track your scouting info
Scouting data collected with the FarmRoad Mobile app is visualized inside the FarmRoad platform. Graphing crop information helps you spot trends and patterns in the lifecycle of your crop.

Digitize crop measurements
Collecting regular crop measurements helps agronomists and farm managers understand how to steer the growth of their plants. Use the FarmRoad mobile app to digitize over 20 crop measurements with your phone to speed up crop registration.

For more information:

Publication date: Wed 25 May 2022

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Blueberry Rust in Western Australia

(Image: Department of Primary Industries and
Regional Development – Agriculture and Food, Western Australia)

The fungus Thekopsora minima causes blueberry rust. It is a serious disease that can cause extensive defoliation and occasional plant death. It is present in most Australian states where industry manage or prevent infection by good farm biosecurity and applying crop management practices that suppress fungal growth.

Blueberry rust found in multiple WA locations

In April 2022 it was found in multiple locations in WA including the Perth metropolitan area, Manjimup, and Swan View. Suspect detections in Bunbury, Busselton, and Kalgoorlie have also been reported to the Department of Primary Industries and Regional Development (DPIRD). It is a declared pest under the Biosecurity and Agriculture Management Act 2007. This means you may not move, sell, or supply plants infected with blueberry rust to others.

Not technically feasible to eradicate

Due to its spread in WA and the factors outlined below, the Department considers it is not technically feasible for the blueberry industry and government to eradicate blueberry rust from WA.

  • High dispersal potential, including spores carried on the wind for long distances.
  • Pest biology favours spread and establishment, making it very difficult to contain.
  • The southwest WA climate is well suited for establishment and spread.
  • Blueberry production in WA is mostly evergreen varieties, providing a green-bridge for rust development.
  • Spread into urban areas would be difficult to detect, eradicate or contain.
  • No reports of successful eradication or containment in Australia or overseas.
  • Chemical controls suppress blueberry rust but do not eradicate it.

Blueberry rust is extremely infective

Blueberry rust is spread via spores carried by wind from infected plants, directly by people wearing contaminated clothing, on equipment that has been in contact with infected blueberries or by introducing infected plants. Young leaves are most vulnerable to rust infection. Rain events can trigger the release of spores and favour infection by increasing the humidity. Leaf wetness, due to rain and dew, provide conditions which assist in the severity of the disease.  Mild temperatures favour spore production and infection with temperatures between 19–25°C highly favourable. The latent period from infection to the observation of symptoms can be 10 days at 20°C for susceptible varieties. Infection leads to premature leaf drop and these leaves play a role in the ongoing disease cycle.


Fungicides control blueberry rust but do not eradicate it. Management is best if fungicides are applied in a preventative manner, prior to conditions that favour infection. The best time to apply preventative fungicides will vary according to variety grown and weather conditions.

Help to identify blueberry rust

Unsure if you have blueberry rust? Use the MyPestGuide® Reporter app to send a photograph to DPIRD. A specialist will examine your photograph and send you a diagnosis.

Refer to https://www.agric.wa.gov.au/pests-weeds-diseases/mypestguide for details on using the MyPestGuide Reporter app.

Changing pest status in Western Australia

In accordance with national and international biosecurity agreements, the Department intends to update the status of blueberry rust in WA to ‘present’ and revoke its declared pest status.

What this means for industry

Removal of import and quarantine restrictions

Where a pest is present and not under eradication or official control, there is no justification for WA import restrictions.

As host plant material and agricultural machinery used in association with hosts are restricted entry into WA based on the absence of blueberry rust, the Department will also revoke specific import restrictions for these items.

Domestic market access

As WA is not free of blueberry rust, host material sent to sensitive markets will need to meet the import requirements as set by the importing authority.

For further information regarding movement and treatment requirements, please see https://www.agric.wa.gov.au/exporting-animals/quarantine-export-restrictions

Management of blueberry rust

The Department will support industry to adopt effective management practices for blueberry rust. This support includes advice on good farm biosecurity and crop management practices that help prevent or reduce blueberry rust infection.

These include:

  • Restrict access to your property. Ensure visitors and equipment come in and go out clean.
  • Prune to create an open canopy. This helps leaves dry faster and reduces humidity and the number of possible rust infections.
  • Monitor your plants regularly: the earlier you can remove infected material, the more likely you will be to keep the rust at a manageable level.
  • Implement a good farm/nursery biosecurity plan.
  • Avoid overhead watering.

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Friday, 06 May 2022 07:36:00 PestNet

Grahame Jackson posted a new submission ‘Why Tomato Crops Today Are So Susceptible to Disease ‘


Why Tomato Crops Today Are So Susceptible to Disease

Growing produce

Anthony P. Keinath By Anthony P. Keinath|May 4, 2022

Why are tomatoes so susceptible to disease? Of three possible answers — aggressive pathogens that specialize on tomato, the tomato plant itself, or the growing environment — it’s not the pathogens.

For example, early blight and late blight can be equally destructive on tomato and potato. Phytophthora blight and fruit rot is worse on pepper than tomato. Is there something about the tomato that makes it inherently susceptible, something medical doctors call a congenital defect? Or is it weather conditions during the growing season? The answer seems to be both.

Same Chromosome Controls Resistance and Size

Tomatoes were domesticated in Southeast Mexico from a wild tomato that resembles a small cherry tomato. The cherry tomato ancestor originated in the humid Amazon rainforests of Northeast Peru and then spread to the Yucatan Peninsula of Mexico, according to a 2020 article in the highly regarded scientific journal Molecular Biology and Evolution.

San Martin, Peru, where ancestral tomatoes still grow wild, is humid with 6 to 13 inches of rain per month, year-round. So, tomatoes should be suited to cropping in humid environments.

But something happened in the chase for larger fruit. Early Mesoamericans who domesticated tomato, as well as modern plant breeders, produce buyers, and consumers wanted large tomato fruit. The average size of a fruit doubled as tomato developed into what passes for an early modern tomato.

Bacterial spot is one of multiple tomato pathogens to be aware of. Susceptibility is linked to genes for large fruit and high yield.
Photo by Zack Snipes

Unfortunately for today’s tomato growers in the Eastern U.S., large-fruited tomato plants are susceptible to a variety of bacterial diseases. That includes bacterial wilt and bacterial spot.

The genes in wild tomatoes that make them resistant to bacterial diseases are found on the same chromosome as genes that control fruit size and yield.

That’s why the resistant offspring of a cross between a tomato parent with decent-sized fruit (but susceptible to bacterial diseases) and a resistant parent (but with small fruit) always have fruit that are too small for current tastes.

Allow Breathing Room

Another likely reason for the prevalence of tomato diseases is our modern, intensive production practices.

Most staked tomatoes are grown with 6 feet between rows and 2 feet between plants. That’s tight spacing for full-grown tomato plants, even after “suckering” to leave only two main side branches.

The large fruits — unlike the original cherry-sized fruits — are too heavy for tomato plants to support without aid from the stake-and-tie production system that originated in the Southeast.

Stringing a mass of foliage together creates humid microclimates perfect for pathogens. On humid summer days, or after a downpour, the inner leaves of the canopy may never dry completely. Continuously wet leaves allow bacteria, fungi, and water molds like late blight to grow continuously — just like they do in a petri dish in the lab.

Simply giving tomatoes more space may be enough to reduce foliar diseases.

A local organic grower spaces tomato rows 12 feet apart instead of the standard 6 feet. This farm had less bacterial spot than nearby conventional farms.

He sprayed the recommended organic products, copper plus Serenade (Bayer Crop Science), while conventional growers sprayed the recommended conventional products, copper plus mancozeb. Both spray programs are moderately effective, so one likely reason for seeing less bacterial spot on the organic crop was the wider row spacing.

Protect Plants from Rain

High moisture in the form of rainfall also damages tomatoes. The processing tomato industry is concentrated in California’s Central Valley. Rainfall there is only five to 20 inches per year. That’s half the annual precipitation in the Midwest, where processing tomato acreage has declined since the 1990s.

One way to protect tomatoes from too much rain is to grow them under high tunnels. Based on a trial at Kansas State, tomato fruit from high tunnels had less postharvest fruit rot and could be stored longer than field-grown tomatoes.

The high tunnel environment also reduces gray leaf spot on the very susceptible heirloom ‘Cherokee Purple’.

In Florida, fruit cracking and decay of beefsteak tomato was consistently two-thirds lower in high tunnels than in the field.

In both locations, the plastic covering of the high tunnel keeps the leaves and fruit dry during rain and protects them from rain-splashed pathogen spores.

Although wild tomato is native to the humid tropics, modern descendants perform better in drier natural or man-made environments.

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Science News

from research organizations

In poplars, two plant hormones boost each other in defense against pathogenic fungi

Date:May 3, 2022Source:Max Planck Institute for Chemical EcologySummary:In contrast to previous assumptions, the defense hormones salicylic acid and jasmonic acid do not always suppress each other in regulating plant chemical defenses against pests and pathogens. In trees, the interplay of both hormones can actually increase plant resistance.Share:


In contrast to previous assumptions, the defense hormones salicylic acid and jasmonic acid do not always suppress each other in regulating plant chemical defenses against pests and pathogens. In trees, the interplay of both hormones can actually increase plant resistance. This is the conclusion researchers from the Max Planck Institute for Chemical Ecology draw in a new study on poplars. The scientists showed that higher levels of jasmonic acid were also detectable in poplars that had been modified to produce increased levels of salicylic acid or that had been treated with salicylic acid. Plants that had higher concentrations of both hormones were also more resistant to the rust fungus Melamspora larici-populina, with no negative effect on growth. Knowledge of the positive interaction of these hormones involved in plant resistance could help to better protect poplars and other trees against pathogens.

The function of plant hormones or phytohormones is to coordinate the growth and development of plants. Moreover, they also control plant immune responses to microbial pathogens such as pathogenic fungi. Until now, there has been a broad consensus in science that the signaling pathways of the defense hormones salicylic acid and jasmonic acid act in opposite directions. Thus, if plants produce more salicylic acid, this would inhibit the production of jasmonic acidand vice versa. Scientists have repeatedly shown this negative interplay in studies of the model plant Arabidopsis thaliana (thale cress) and many other annual herbs. “Contrary to the assumption that the salicylic acid and jasmonic acid hormone signaling pathways work in an opposite manner, we had already observed in our earlier studies on poplar trees that both of these hormones increase in response to infection by pathogenic fungi. Therefore, the main research question was to determine the interaction between these two defense hormones in poplar,” Chhana Ullah, first author of the publication, explains the starting point of the current study.

To study experimentally how salicylic acid levels affect the formation of jasmonic acid, the scientists genetically modified experimental plants of black poplar (Populus nigra) native to Germany so that they produced higher amounts of salicylic acid than control plants. In another experiment, they applied salicylic acid to the poplar leaves of genetically unmodified plants. “We manipulated salicylic acid levels in poplar by genetic engineering and direct chemical application, after which we conducted extensive chemical analyses of the plants with and without fungal infection. This allowed us to separate the effects of salicylic acid from other factors and show that it directly stimulates jasmonic acid production,” explains Chhana Ullah.

Plants that contained high levels of salicylic acid also had higher concentrations of jasmonic acid. In addition, these plants produced more antimicrobial substances, known as flavonoids, even if there was no infection with a pathogen. Further comparative studies with plants that produced high levels of salicylic acid and control plants that had each been infected with the rust fungus Melamspora larici-populina showed that high levels of salicylic acid made poplars more resistant to fungal attack.

Surprisingly, higher fungal resistance due to increased defenses did not negatively affect plant growth, as had been observed in Arabidopsis and other annual herbs. In Arabidopsis, either salicylic acid or jasmonic acid takes control of the immune response, while the other hormone is suppressed. Salicylic acid is produced in higher amounts after attack by biotrophic pathogens that do not kill plant tissue and feed on living plant material, while jasmonic acid is increased after attack by insects or necrotrophic pathogens that feed on dead plant tissue. “The negative interplay between the defense hormones salicylic acid and jasmonic acid in plants like Arabidopsis enables the plant to prioritize protection against one kind of enemy. Small herbs like Arabidopsis may benefit from such a narrow focus because they lack the resources to defend against different kinds of enemies at once. This may also be the reason why Arabidopsis plants reduce their growth rate when in a defense mode,” says Jonathan Gershenzon, head of the Department of Biochemistry where the study was conducted.

In contrast to annual herbs such as thale cress, resources are usually less limited for trees and other woody plants. Moreover, because of their long lifespan, trees are often attacked simultaneously by different enemies, such as fungal and bacterial pathogens, leaf-eating caterpillars, and wood-destroying insects. They may have evolved to use the salicylic and jasmonic acid signaling pathways together for defense. The greater availability of resources in long-living woody plants may also be the reason why high concentrations of salicylic acid do not affect plant growth in poplars.

The researchers were surprised to find that high levels of salicylic acid in poplars did not activate so-called pathogenesis-related (PR) genes, although these are established markers for the salicylic acid signaling pathway in Arabidopsis. “However, we found that the magnitude of PR gene induction was positively correlated with the susceptibility of poplar to rust. Apparently, the activation of PR genes in poplar is not regulated by salicylic acid signaling, but by a different mechanism,” Chhana Ullah explains.

The team of scientists led by Chhana Ullah still has to find out exactly how the molecular mechanism of the positive interaction between salicylic acid and jasmonic acid works in poplar. They also want to know which role PR genes play in poplar and other woody plants. What is certain, however, is that a fundamental knowledge of the positive interaction between salicylic acid and jasmonic acid in poplar and other related trees could make an important contribution to better protecting these plants from pest infestation and disease. Or, as Jonathan Gershenzon notes: “Poplars are known as the trees of the people for their diversified uses by humans, hence the genus name Populus: the Latin name for people. Incredibly fast-growing, poplars are cultivated as short-rotation woody crops and are extremely important of the pulp and paper industry. They are also desirable for biofuels.” Improving their protection therefore serves us all.

Story Source:

Materials provided by Max Planck Institute for Chemical EcologyNote: Content may be edited for style and length.

Journal Reference:

  1. Chhana Ullah, Axel Schmidt, Michael Reichelt, Chung‐Jui Tsai, Jonathan Gershenzon. Lack of antagonism between salicylic acid and jasmonate signalling pathways in poplarNew Phytologist, 2022; DOI: 10.1111/nph.18148

Cite This Page:

Max Planck Institute for Chemical Ecology. “In poplars, two plant hormones boost each other in defense against pathogenic fungi.” ScienceDaily. ScienceDaily, 3 May 2022. <www.sciencedaily.com/releases/2022/05/220503141350.htm>.

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In this issue:

From the President
75th Anniversary Symposium and Conference
Photo Competition

2021 Scholarship Winners 
 Members in the News
 Related Events
NZPPS Corporate Members

We look forward to your feedback.From the President
         The next conference, at the Christchurch Town Hall, in August 2022, will be a celebration of 75 years of the Plant Protection Society. Several ideas to mark the 75th anniversary are in progress, some of which are reported in this newsletter. To begin with, a special 75th anniversary logo was designed for this year, which is depicted in this newsletter and on the website. Those of you with keen eyes may notice some slight modifications to the logo. Since we engaged a professional graphic designer to create the 75th logo and a new banner, it was a good opportunity to make some improvements to the existing logo. The revised logo is higher resolution, and the arrows embracing the plant have been tightened and made more fluid. The colour version uses a two-tone approach, with light and dark green, giving a more unique and modern look.

Importantly, the logo remains the same, as it still captures the essential purpose of the Society ‘to pool and exchange information’ related to plant protection. Given the anniversary occasion, it is timely to reflect on the history and meaning of Society’s logos, past and present. In the formative years of the Society, as a weed-control conference, there was no logo but, from 1962 until 1983, the cover of the published proceedings featured an illustration of a weed or pest. In 1984, the Society developed its first logo, which was the depiction of a weed (possibly a buttercup species) and a pest (a scarab grub), contained within a hexagon. The weed was in the light (aboveground) section, and the scarab in the dark (belowground) section. At a glance, it is a literal depiction of the focus of the Society at the time, weeds and pests.However, the logo possibly had greater significance, reflecting a shift in thinking at the time, away from pesticides as the panacea, towards integrated pest management. Hexagons are ubiquitous in nature and used to symbolise harmony. And the perfectly balanced dark and light halves of the harmonious hexagon conjure a yin and yang interconnectedness.

As the scope of the society further evolved, encompassing plant protection research and extension activities in the broadest sense, a new logo was needed. In 1996, the Society adopted its current logo, which was described by the President at the time, Richard Falloon, in his Presidential Address at the 49th conference. The arrows indicate interactions and information exchange that occurs through the interdisciplinary approach to plant protection. The protective circle conveys plant health resulting from plant-protection activities, and sustained plant health is depicted as the plant grows through the circle.

I do not know who designed either of the logos, and I have possibly over interpreted the first logo. If any members know more about the logos or their designers, please get in touch. In the coming months, the Executive will be reaching out to previous Presidents and others who have had an enduring impact on the Society to invite them to share their reminiscences, learn about past success stories, and receive advice for the future. Mark your calendars, submit your abstracts, and stay tuned for more news about this year’s symposium and conference.
Mike CrippsThe NZPPS Executive are delighted to advise that theNZPPS 75th Anniversary Symposium and Conferenceare proceeding as in-person events at the
Christchurch Town Hall.
Dame Juliet Gerrard will give the  conference opening address on Tuesday 9 August.Symposium: 8 August 2022  
Plant pathogens that keep us awake: past, present and future threats to native species.
https://nzpps.org/events/nzpps-symposium-2022/A day of invited presentations focussed on microbial threats to our native taonga plants. Leading scientists, kaitiaki, international experts and representatives from government agencies will bring attendees up to date with progress on myrtle rust, kauri dieback, Pacific biosecurity, Ceratocystis, Xylella and more. The day will conclude with a networking and poster session. Those interested in submitting a poster for the symposium should submit an abstract (maximum 250 words) to Renee Johansen (JohansenR@landcareresearch.co.nz) by 31 May 2022. Conference: 9-11 August 2022
Celebrating 75 years of the New Zealand Plant Protection Society
Three full days of presentations including special sessions, conference dinner with 75th anniversary cake for dessert and a slideshow of competition photos

The first session on Tues 9 August has been reserved for participants who wish to present a talk on the symposium topic. Abstract submission for the 2022 conference is openDeadline is 30 April 2022.NZPPS 75th Anniversary
Photo Competition
 Get clicking and enter your pictures here for the 75th anniversary photo competition. The photo within each category with the most member votes wins. Categories: Plant protection in action Plant pests Plant diseases  Plant weeds The growing crop Plant protection science People in plant protection Winners and their photos will be showcased on the NZPPS website, at the conference and in the newsletter. Closing date: 30 June 2022. NZPPS Plant Protection MedalThis medal has been instituted by the New Zealand Plant Protection Society to honour those who have made exceptional contributions to plant protection in the widest sense. The medal will be awarded based on outstanding services to plant protection, whether through research, education, implementation or leadership.Details of the nomination process are available here.

Deadline 1 July 2022.2021 NZPPS Research ScholarshipAshleigh Mosen is an MSc student at Massey University.Development of a novel disease control strategy to protect Pinus radiata from Dothistroma needle blight.
The hemibiotrophic fungus Dothistroma septosporum is a foliar pathogen of Pinus radiata that causes a disease known as Dothistroma needle blight (DNB). This forest tree disease is destructive to pines, resulting in dieback of needles, premature defoliation and in severe cases tree death. Necrotic lesions, which are seen on infected needles become a brick-red colour, characteristic of the fungus producing a toxic virulence factor called dothistromin. DNB is an economically important disease impacting upon New Zealand’s forest industries, costing the NZ economy ~$20 million per year. Current control measures include copper fungicide spraying, silvicultural methods such as pruning and thinning, and breeding pine trees for increased resistance to pathogen attack. A radical new approach, spray-induced gene silencing using RNA technology, has great potential to control DNB.

 My project explores the potential for applications of this technology by using RNA molecules, that specifically target and silence pathogen genes, to effectively lower the virulence of the pathogen. The candidate genes DsAflR (dothistromin pathway regulatory protein) and eGFP (enhanced green fluorescent protein) were pursued as targets for RNA silencing trials. As a result, dothistromin production and virulence of the pathogen is expected to be reduced, and decreased DNB symptoms on pine. Confocal microscopy analyses have been performed demonstrating dsRNA uptake into fungal cells. In vitro and in planta silencing trials suggest no clear evidence whether there is knockdown of AflR and eGFP. However quantitative real time PCR analyses are in progress to determine if there is a reduction in transcript levels. Disease symptoms have been monitored on infected pine needles and are showing reduced lesions, as a result of spraying with dsRNA targeting AflR. In combination, biomass assays will verify if there is a reduction in fungal biomass and hence suppressed virulence. The effects of timing and concentration of the dsRNAs have been established to achieve maximum silencing.

By the end of my project I hope to determine if treatment with the dsRNA has had any effects in terms of suppression of the target genes and create a framework to optimise silencing in this forest pathogen for future studies. This could be an effective solution to augment current control measures and could be applicable to agricultural and horticultural disease control. My project is of great importance to NZ, its forest industries, and other plant-based industries. This will be the first study of its kind in NZ, which will be a blueprint for controlling other forest, agricultural and horticultural pathogens.Dan Watkins Scholarship in
Weed Science

Robert Gibson II is a PhD student at Lincoln University.

Establishment risk of wilding Pinus radiata and its hybrid in New Zealand high country.

Non-native conifers have been well integrated throughout New Zealand’s landscape for amenity and shelter, erosion control, and commercial forestry purposes. Unwanted individuals that self-perpetuate from these cultivations are categorised as wildings. Wildings are the largest weeds in New Zealand and one of the biggest weed problems, posing a significant threat to the biodiversity and functioning of native ecosystems, particularly on the South Island. The conifer species most tightly interwoven throughout New Zealand’s landscape, industry, and culture is Pinus radiata. As a result, P. radiata propagules are genetically bred and widely distributed across both main islands with sufficient mutualists; all factors that can increase the risk of wilding. From a commercial forestry and afforestation perspective, previous research suggests Pradiata has a limit of establishment around 700 m due to cold-intolerance (i.e. reduced germination, growth, and cone production). As a result, a natural hybrid between Pradiata and Pattenuata is being assessed as commercial forestry and afforestation programmes shift to higher elevations. The aim of this research is to assess the potential threat of wilding establishment of both taxa in high country native grasslands and shrublands. This will be achieved through evaluating the potential biotic and abiotic barriers associated with these ecosystems on the fate of seeds and seedlings along an elevation gradient from the putative limit of establishment (< 700 m) to the high country (900 m and 1100 m). Across six sites and three microhabitats, this study is investigating: 1) seed viability, seed loss to predation and the potential for deposition into the soil seed bank; 2) emergence and seedling establishment; and 3) the response of 12-month-old seedlings to herbivory, and the interaction between herbivory and climate. This study isolates each seed and seedling stage with a different experiment to disentangle the influence of different barriers and how the magnitude of those barriers may fluctuate across multiple life stages to gain insight into the big picture of what may induce establishment failure of these two taxa. Lastly, this research will determine whether the information around the elevation limitation of P. radiata establishment from commercial plantations holds under natural conditions, and whether any of those barriers may be surpassed by the inclusion of the hybrid into high country ecosystems.Members in the News2018 NZPPS Medal winner Barbara Barratt has been made a Fellow of the Royal Society Te Apārangi for pioneering internationally relevant research into the biosafety of introduced biocontrol agents for insect pests and for leading a major theme in a multi-agency research collaboration focused on border biosecurity risk assessment.  Read more here.NZPPS editor Ruth Falshaw is the latest person to be profiled in the  “Women in Horticulture” series published in the NZGrower magazine. The publisher Horticulture NZ and author Elaine Fisher have given permission for the article to be reproduced and it can be viewed hereRelated EventsCanterbury University is running a webinar entitled: Mahi Tahi: work together to build biosecurity capability on 13 April 2022. Find out more at: https://www.canterbury.ac.nz/biosecurity-innovations/news-and-events/mahi-tahi-.html12th International Symposium on Adjuvants for Agrochemicals Bordeaux 24 – 29 April 2022.  https://www.isaa2022.org/general-information/The Weed Management Society of South Australia (WMSSA), on behalf of The Council of Australasian Weed Societies (CAWS), will be hosting the 22nd Australasian Weeds Conference (22AWC) at Adelaide Oval from 25-29 September 2022. https://eventstudio.eventsair.com/22AWCThe 8th International Weed Science Congress: “Weed Science in a Climate of Change” will be held in Bangkok from 4 – 9 December 2022.https://www.iwsc2020.com/Books

For sale
There is a 10% discount for NZPPS members on NZPPS titles purchased from Nationwide Book Distributors:

351 Kirikiri Road, Oxford 7495
 0800 990 123
Email: books@nationwidebooks.co.nz
Web: http://www.nationwidebooks.co.nzBest sellers include:
Farewell Silent Spring – the New Zealand Apple Story
An Illustrated Guide to Common Weeds of New Zealand (Third Edition)
An Illustrated Guide to Weed Seeds of New Zealand
An Illustrated Guide to Common Grasses, Sedges and Rushes of New Zealand
A Guide to the Identification of New Zealand Weeds in Colour
Free to NZPPS members:Hard copies of:

Future Challenges in Crop Protection 
Surveillance for Biosecurity2010 Microbial Products 
Paddock to PCR
The Plant Protection Data Toolbox 
Utilising Plant Defences for Pest Control 

Contact the Secretary at secretary@nzpps.org if you would like one.NZPPS Corporate MembersAgResearch Ltd
Adama New Zealand Ltd
Arxada New Zealand Ltd
BASF New Zealand Ltd
Bayer New Zealand Ltd
Corteva Agriscience
Environmental Protection Authority
Foundation for Arable Research
Horticulture New Zealand
Ministry for Primary Industries
New Zealand Apples & Pears Inc.
New Zealand Avocado
New Zealand Winegrowers
Nufarm NZ Limited
Peak Research Limited
Staphyt Research Ltd
Syngenta Crop Protection Ltd
The New Zealand Institute for Plant and Food Research Ltd
UPL New Zealand Ltd
Zespri International Ltd
Dr Mike Cripps
Ph: (03) 325 9936
Vice President
Dr Hayley Ridgway
Plant & Food Research
Ph: (03) 325 9450

Immediate Past President
Dr Eirian Jones
Lincoln University
Ph: (03) 423 0746
Jenny Taylor
PO Box 21839
Henderson 0650
Ph: (09) 8128506
Mob: (027) 477 9821
Dr Jason Smith
Horteye Ltd
Mob: (027) 249 9370
 Journal Editor/
Communications Manager

Dr Ruth Falshaw
Mahana Editing Services
Mob: (027) 380 9839
Website Editor
Mike Barley
mike@hortplus.comCommittee Members
Rebecca Campbell, Plant & Food Research, Motueka

Joy Tyson, Plant & Food Research, Auckland

Stephen McKennie, Arxada NZ Ltd, Auckland

Laura Tomiczek, Ministry for Primary Industries, Auckland

Rebecca Fisher, Horticulture New Zealand, Wellington

Dr Soonie Chng, Plant & Food Research, LincolnCopyright © 2022 New Zealand Plant Protection Society Inc.All rights reserved.

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Newly Discovered Protein in Fungus Bypasses Plant Defenses


ARS News ServiceSunflower plant infected with Sclerotinia head rot.
A newly discovered protein helps the fungus that causes white mold stem rot in sunflowers and more than 600 other plant species bypass the plants’ defenses. Newly Discovered Protein in Fungus Bypasses Plant Defenses For media inquiries contact: Kim Kaplan, 301-588-5314 Pullman, Wash., April 25, 2022

A protein that allows the fungus that causes white mold stem rot in more than 600 plant species to overcome plant defenses has been identified by a team of U.S. Department of Agriculture Agricultural Research Service and Washington State University scientists.Knowledge of this protein, called SsPINE1, could help researchers develop new, more precise system of control measures for the Sclerotinia sclerotiorum fungus, which attacks potatoes, soybeans, sunflowers, peas, lentils, canola, and many other broad leaf crops. The damage can add up to billions of dollars in a year of bad outbreaks.S. sclerotiorum fungi cause plants to rot and die by secreting chemicals called polygalacturonases (PG), which break down the plant’s cell walls. Plants evolved a way to protect themselves by producing a protein that stops or inhibits the fungus’ PG, labeled PGIP, which was discovered in 1971. Since then, scientists have known that some fungal pathogens have a way to overcome plant’s PGIP. But they had not been able to identify it.”What you have is essentially a continuous arms race between fungal pathogens and their plant hosts, an intense battle of attack, counterattack and counter-counterattack in which each is constantly developing and shifting its chemical tactics in order to bypass or overcome the other’s defenses,” said research plant pathologist Weidong Chen with the ARS Grain Legume Genetics Physiology Research Unit in Pullman, Washington, and leader of the study just published in Nature Communications.The key to identifying SsPINE1 was looking outside the fungi cells, according to Chen.”We found it by looking at the materials excreted by the fungus,” he said. “And there it was. When we found this protein, SsPINE1, which interacted with PGIP, it made sense.”Then to prove that the protein SsPINE1 was what allowed Sclerotinia to bypass plants’ PGIP, Chen and his colleagues deleted the protein in the fungus in the lab, which dramatically reduced its impact.”I got goosebumps when we found this protein,” said Kiwamu Tanaka, an associate professor in Washington State University’s Department of Plant Pathology and a co-author on the paper. “It answered all these questions scientists have had for the last 50 years: Why these fungi always overcome plant defenses? Why do they have such a broad host range, and why are they so successful?”The discovery of SsPINE1 has opened new avenues to investigate for controlling white mold stem rot pathogens, including possibly even more effective, more targeted breeding to make plants naturally resistant to sclerotinia diseases. And the team has showed that other related fungal pathogens use this counter-strategy, which only serves to make this discovery even more important.This research is part of the National Sclerotinia Initiative, a multiorganization effort that ARS created to counterattack S. sclerotiorum because the fungus does so much damage around the world.The research team also included scientists from USDA-ARS, WSU, Northwestern A&F University in Shaanxi, China, Wuhan Polytechnic University in Wuhan, China and Huazhong Agricultural University in Wuhan.The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.
Interested in reading more about ARS research? Visit our news archiveU.S. DEPARTMENT OF AGRICULTURE
Agricultural Research Service

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APRIL 18, 2022

Uncovering the spread of coffee leaf rust disease

by University of Tsukuba

Uncovering the spread of coffee leaf rust disease
Credit: raksapon/Shutterstock

Coffee is one of the world’s most popular drinks, yet there are still many unknowns in the coffee-growing business. Now, researchers from Japan have shed new light on the nature of a disease that seriously affects coffee plants.

In a study published this month in Frontiers in Plant Science, researchers from the University of Tsukuba and Ibaraki University have revealed that coffee leaf rust (CLR) disease is widespread in the main coffee-growing regions of Vietnam, the world’s second-largest coffee producer.

Rusts are plant diseases named after the powdery rust- or brown-colored fungal spores found on the surfaces of infected plants. CLR fungus, Hemileia vastatrix, causes CLR disease in Coffea plants—the source of coffee beans. This disease severely affects the plants, resulting in high yield losses and lowering bean quality; developing effective and practical ways of managing the disease is essential for mitigating this problem. The best way to control CLR is by using disease-resistant plant varieties. However, there have been recent reports of CLR outbreaks in coffee-growing regions where rust-resistant varieties are planted.

“To control this disease, we need to understand rust population diversity,” says senior author of the study, Associate Professor Izumi Okane. “We must also identify the genetic variations that underpin it, and anticipate potential future variations.”

To do this, the researchers examined the occurrence of CLR disease in key coffee-producing regions of Vietnam, assessed the current population structure and genetic diversity of the CLR fungus via genetic sequencing, and estimated the geographic region where H. vastatrix first established, as well as its direction of migration between Vietnam’s main coffee-producing areas.

The results showed a high incidence of CLR disease in most of the regions investigated, and that H. vastatrix populations in Vietnam shared a close genetic relationship with several Central and South American populations. The study also uncovered potential starting points and migration routes of H. vastatrix in Vietnam’s coffee-growing regions. The spread of CLR from northern to southern Vietnam revealed that agents other than wind and monsoon were involved in moving spores from an infected region to other areas.

“Our study highlights the need to consider human-mediated activities, because they may quickly accelerate the genetic diversification of rust fungi populations,” explains Associate Professor Okane.

The results of this study have revealed new information on the genetic diversity of H. vastatrix in Vietnam and Central and South America. The researchers’ findings will help to predict the spread of this fungus in the future. Furthermore, seedling sources and human activities have been highlighted as factors that should be considered in the coffee-growing industry for the control of CLR disease.

Explore further

Fungus that eats fungus could help coffee farmers

More information: Cham Thi Mai Le et al, Incidence of Coffee Leaf Rust in Vietnam, Possible Original Sources and Subsequent Pathways of Migration, Frontiers in Plant Science (2022). DOI: 10.3389/fpls.2022.872877

Journal information: Frontiers in Plant Science 

Provided by University of Tsukuba

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GeoPotato: How Data Gives Bangladesh’s Potato Farmers a New Tool in the Fight Against Late Blight

Wed, April 20, 2022, 8:26 AM·4 min read

Northampton, MA –News Direct– Bayer

Powered by satellite data and powerful analysis models, GeoPotato is designed to enable preventive spraying, easier crop protection decisions, and improved farmer income

GeoPotato, a geodata-driven early warning system for late blight in potatoes, has entered a full commercial roll-out in Bangladesh, and could reach as many as 1 million smallholder farmers in the coming years.

Devised by Wageningen Plant Research, Terrasphere, mPower, Bayer and governmental institutions, GeoPotato’s cutting edge technology employs a sophisticated risk assessment algorithm evaluating many factors impacting crop development on the field– including satellite data, weather forecasts, disease cycles and crop biomass growth – to assess key risk factors for late blight development (susceptible host, conducive environment and pathogen presence) on a highly localized basis.

When it predicts a disease outbreak, it sends farmers an early alert via SMS or voicemail, three days before the outbreak is forecasted to occur. It also advises which fungicidal product would be most effective to help growers take action in a fast and efficient manner.

After running trials for the last five seasons, GeoPotato was launched publicly on 1 November 2021. To maximize its impact, project partners have reached out to more than 50,000 farmers in key potato-producing areas. Ultimately, they intend to expand it to all of Bangladesh, as well as parts of India, reaching more than 1 million farmers and making a significant step towards Bayer’s commitment of empowering 100 million smallholder farmers by 2030.

Scaling up GeoPotato, scaling up yields

After rice potatoes are the second most important food crop in Bangladesh, but they face a severe threat from late blight, a fast-spreading disease that can devastate as much as 57% of Bangladesh’s potato production each year. Late blight can have widespread and highly damaging effects on farmer incomes and potato prices.Story continues

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APRIL 18, 2022

Scientists record first case of harmful bacteria in ubiquitous weed found throughout US

by University of Florida

Scientists record first case of harmful bacteria in ubiquitous weed found throughout U.S.
Credit: University of Florida

Scientists at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) have recorded the first North American case of a harmful phytoplasma disease known for its threat to fruit, vegetable and ornamental crops in South America and the Middle East.


To make matters worse, scientists confirmed the host for the disease to be one of the most noxious and rapidly spreading weeds commonly found in a wide range of environments throughout the United States and into Canada.

Findings of the “First report of ‘Cadidatus Phytoplasma brasiliense‘ in North America and in a new host, yellow nutsedge (Cyperus esculentus)” were just published in the journal Plant Health Progress.

“The host of the disease is known as one of the most widespread and problematic weeds found everywhere—called yellow nutsedge,” said Brian Bahder, assistant professor of entomology at UF/IFAS Fort Lauderdale Research and Education Center. “It is one of the most aggressive weeds that commonly grows in lawns, home landscapes, vegetable and flower gardens and agricultural systems.”

The phytoplasma species called Candidatus Phytoplasma brasiliense is documented in regions of Brazil and Peru to harm hibiscus, papaya and cauliflower. Subsequently, research showed the same species infects peaches in the Middle East country of Azerbaijan.

Bahder and his team confirmed the phytoplasma and host in Fort Pierce. They found it while conducting research for a different disease—lethal bronzing—that attacks palm trees. Scientists were surveying and testing samples of grasses in hopes of finding a reservoir for lethal bronzing.

Research has shown that the adult planthopper insect that carries lethal bronzing feeds on the palm’s canopy, and the nymphs have been recorded among more than 40 species of grasses and sedges.

Because of the close association of nymphs with grasses and sedges, speculation has risen about the ability of these plants to serve as a reservoir for the lethal bronzing phytoplasma, Bahder said.

For the survey, scientists sampled three of the most abundant weeds known to serve as a host to the nymphs, yellow nutsedge being one of them.

While testing the samples, three of the outcomes resulted in a positive result.

“We thought we had found lethal bronzing in one of the grasses, so we proceeded to genetically sequence the sample,” said Bahder. “The results confirmed it was not lethal bronzing but that it was another phytoplasma.”

The DNA sequencing of that specimen confirmed their findings of a new phytoplasma in this weed, recorded for the first time in North America.

Implications of the disease and its spread through this weed cause scientists to consider it a threat to agriculture and ornamental industries. UF/IFAS scientists are seeking funding for the next steps of research.

“The next logical step is to find out which insect is spreading the disease. The good news is that we caught this early,” said Bahder. “We don’t know if this is an isolated incident or if the insect is spreading in the grass, and if it will feed on the papaya, hibiscus or cauliflower—which are economically important in Florida. The point is that we don’t know the extent of this disease in Florida or what threat it poses.”

Explore further

Palm tree disease in Florida transmitted by traveling bug from Jamaica

More information: Brandon Di Lella et al, First report of ‘Candidatus Phytoplasma brasiliense’ in North America and in a new host, yellow nutsedge (Cyperus esculentus), Plant Health Progress (2022). DOI: 10.1094/PHP-03-22-0027-BR

Provided by University of Florida 


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