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Archive for the ‘Weeds’ Category

Largest UK weed survey reveals Italian ryegrass challenge

Farm Weekly

© Blackthorn Arable© Blackthorn Arable

Results from the UK’s largest survey on Italian ryegrass has shown a complex and variable picture of herbicide resistance in the weed, emphasising the need for growers to test and understand the populations on their farms to achieve better control.

However, rising levels of resistance to commonly used herbicides are not the only cause of control difficulties, reveals weed specialist John Cussans of Niab, who also highlights application timing and better use of diversified modes of action as important actions.

See also: Tips on tackling five weed issues in no-till systems

“There is scope to improve practice, as there are too many fire brigade treatments being made,” he advises.

“It’s a complicated landscape when it comes to resistance mechanisms, but better attention to detail will help to avoid poor decision-making.”

Conducted by Niab with funding from Bayer, the survey of 197 samples from across the country investigated current on-farm control practice, as well as testing each Italian ryegrass sample for sensitivity to flufenacet, pinoxaden (Axial) and ALS herbicides (Atlantis).

In addition, 22 of the weed samples were used in a cross-resistance study, to understand any correlations between sensitivity to a wide range of herbicides, including glyphosate.

Post-emergence herbicides

“While the performance of post-emergence herbicides is significantly affected by resistance, it was lower than expected,” says Mr Cussans. (see “Post-emergence herbicide sensitivity”)

“The fact that a large number of samples are still susceptible to herbicides goes against the perception that many have about post-emergence chemistry.”

Dropping the use of perfectly good herbicides tends to happen when the resistance threat is exaggerated, he explains, which is why a better understanding of the situation on individual farms is so important.

Pre-emergence herbicide

When it comes to pre-emergence herbicides, all 197 samples were tested for sensitivity to straight flufenacet.

One-third of them showed either reduced sensitivity or resistance, reflecting that the selection pressure has been there for some time.

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Visit our Know How centre for practical farming advice

“If you pile on flufenacet, you will select resistance to it,” he says. “Of course, in practice it isn’t used alone – it is tank-mixed and sequenced with other actives.”

There are some populations of Italian ryegrass that are completely resistant to flufenacet – which makes it different to the situation with blackgrass, where there has been a shift in sensitivity, rather than complete failure.

Post-emergence herbicide sensitivity (% of samples)
 Atlantis  Axial
S45.645.6
R7.7   6.2
RR24.132.3
RRR 22.615.9
Pre-mergence herbicide sensitivity (% of samples)
 Flufenacet
Sensitive70.6
Significantly Reduced17.3
No Control9.6

Resistance testing

Further analysis showed regional differences between the three herbicides tested, with control from flufenacet being lower in the South East, North and Midlands.

“If you have an emerging issue with pre-emergence herbicides, you need to know about it. Get resistance testing done, preferably on a field-by-field basis – national statistics will make no difference to managing your weed populations.”

Even populations collected from two fields on the same farm can show differences in herbicide sensitivity, he warns, reflecting the very variable herbicide sensitivity present around the country.

Cross-resistance findings

A subset of 22 populations was used to test more herbicides and understand any correlations between them, as well as to look at glyphosate sensitivity.

The strongest correlation is between the existing pre-emergence actives – flufenacet, pendimthalin and prosulfocarb – while aclonifen is weakly correlated with sensitivity to existing pre-emergence products.

“If you have flufenacet resistance on the farm, you need to bring in other modes of action,” advises Mr Cussans. “Where three actives are combined, such as Liberator + Proclus, it largely overcomes flufenacet resistance.

“Broadening the base by combining modes of action helps to stabilise ryegrass control. That fact that we have two new modes of action this year in aclonifen and cinmethylin, and another coming next year, will help.”  

Having a stronger, more diverse base for Italian ryegrass control is important, he stresses.

“Ryegrass is more capable of overcoming herbicides and we know there is a degree of cross-resistance between existing pre-emergence chemistry.

“For this reason, it’s important to combine modes of action.”

Glyphosate sensitivity

There has been a shift in sensitivity to glyphosate in some problematic UK Italian ryegrass populations, but it is not resistance, confirms John Cussans.

The status of 50 difficult weed populations collected in 2019 was checked for their sensitivity to glyphosate at a range of doses, with some variation showing.

“We do not have glyphosate resistance in the UK, but we are as close as we’ve ever been to it,” he cautions. “That’s why we must monitor it and steward the product.”

Glyphosate sensitivity is totally independent of in-crop herbicide use, with the correlation between glyphosate sensitivity and sensitivity to other herbicides being very poor.

However, there is no doubt in Mr Cussan’s mind that poor practice will lead to glyphosate resistance, as it has been possible to select for glyphosate resistance in high-risk scenarios in glasshouse work.

“We must avoid any survivors of glyphosate applications going on to set seed.”

As a result, growers must take ownership of this issue and follow published guidance, he advises.

That is a view shared by Roger Bradbury, technical specialist at Bayer, who stresses the need to apply glyphosate at the right time, with the right dose for the target weed and with good application technique.

He refers growers to the latest Weed Resistance Action Group guidelines, which recommend a maximum of two glyphosate applications after harvest, before drilling the next crop, and stress the importance of monitoring herbicide performance and investigating any reasons for poor control.

“Everyone needs to be aware of the risks and do all they can to prevent resistance to selective herbicides.”

Aclonifen approval in barley

Bayer’s Proclus (aclonifen) has been approved in a tank-mix with Liberator (flufenacet +  diflufenican) for pre-emergence weed control in winter barley, adding a new mode of action and expanding the options for grassweed control in the crop.

A lower application rate of 1 litre/ha + 0.6 litre/ha Liberator, compared with 1.4 litres/ha in winter wheat, means the levels of weed control are slightly less – with a 7% uplift in Italian ryegrass recorded in Bayer trials and a 5-6% improvement in blackgrass control.

Winter barley’s earlier drilling date and more limited herbicide choice can make it a challenging crop for weeds, says Bayer’s Tom Chillcott, who points out that including aclonifen in the pre-emergence mix gives more protection and helps with resistance management.

“Having a new mode of action in barley adds another layer of protection and helps to take the selection pressure off flufenacet.”

As aclonifen sits on the soil surface, weeds have to grow up through it before it takes effect, he adds.

“That means seed-bed preparation, drilling depth and application timing all matter, especially as aclonifen can be a bit hot in some scenarios, and barley is a more sensitive crop.”

A minimum sowing depth of 3.2cm and application within 48 hours are important, as is avoiding heavy rain soon after application.

It will be sold as a co-pack of Proclus and Liberator, as in wheat, and will add £10/ha to pre-emergence costs in barley.

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JUNE 22, 2022

Timing is everything for weed management

by Jim Catalano, Cornell University

Timing is everything for weed management
Bryan Brown, integrated weed management specialist for New York State Integrated Pest Management, stands in a soybean field that lost 50% of its yield to weed competition, even after several herbicide applications. Credit: Cornell University

Farmers can tailor their efforts to control weeds more effectively by pinpointing when a particular weed will emerge, according to a new Cornell University study.

Researchers in the College of Agriculture and Life Sciences reviewed past studies on the peak timing of emergence for 15 troublesome weed species in the Northeast, as well as potential ways to use this knowledge, in their study, “Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast U.S.,” published June 21 in the journal Frontiers in Agronomy.

“There are lot of different weed management tactics out there, and most of them can be improved with some consideration of what weed species you have and when they emerge,” said lead author Bryan Brown, integrated weed management specialist for New York State Integrated Pest Management and adjunct assistant Professor in the School of Integrative Plant Science’s Horticulture Section, in the College of Agriculture and Life Sciences. “In this paper, we provided a framework starting with those tactics that are easiest to tailor or adjust—all the way up to revamping a cropping system—based on avoidance of certain weed species.”

As an example, Brown pointed to common ragweed. “We found that in most of the literature, common ragweed had finished up its emergence by June 1,” he said. “So, if you’re able to wait to till and plant your field until after June 1, then you’ve effectively avoided common ragweed for the season.” Conversely, if a field is riddled with mid- or late-season weeds, planting earlier can help give crops a head start to outcompete them.

When it comes to controlling weed seedlings using herbicides or shallow tilling, control is most effective soon after weeds emerge, so knowing when different weed species grow can help farmers plan ahead.

Farms with flexible crop rotations can leave the ground bare, or perhaps cover-cropped, during the period when their most problematic weed emerges. By controlling that species, they essentially remove its weed seeds from the soil so it will be less of a problem in the future.

The researchers found that the timing of weed emergence varied among previous studies due to factors such as weather, soil temperature and moisture.

“Naturally, that’s going to vary from year to year and from study to study,” Brown said. “But the big surprise to me was that among previous studies that modeled weed emergence, when we input identical weather data, there was still variation in when they expected weeds to emerge. That highlights the regional differences in soils and weed genetics.”

As the models improve by incorporating regional differences, the researchers hope to work with the Network for Environment and Weather Applications to give farmers direct access to weather-based weed emergence predictions.

“As weed management becomes more challenging, I think that this type of planning is going to become more important,” Brown said. “Hopefully, as those emergence models become more accurate we’ll be able to use these tactics to even better use and really fine-tune the timing of our weed management.”


Explore further

Examining the impact of herbicide-resistant crops on weed management


More information: Bryan Brown et al, Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast USA, Frontiers in Agronomy (2022). DOI: 10.3389/fagro.2022.888664

Provided by Cornell University 

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Advances in integrated weed management

Editor

Professor Per Kudsk is Head of the Crop Health Section in the Department of Agroecology at Aarhus University, Denmark. An internationally-known expert in integrated weed management, he is a former President of the European Weed Research Society. Professor Kudsk has played a leading role in EU research projects such as IWMPRAISE and the ENDURE Network as well as in the European Plant Protection Organisation (EPPO).

Dimensions:

229x152mm
6×9″

Publication date:

26 April 2022

Length of book:

452 pages

ISBN-13: 9781786767455

HardbackEbook (VitalSource)

£150.00View/buy chapters 

 Request Permissions

Description

Weed management continues to face many challenges, including herbicide resistance, invasive species, climate change and how best to deploy the range of non-chemical control methods available. To tackle these challenges, integrated weed management (IWM) needs to evolve to embrace a more holistic, landscape-based agroecological approach.

Advances in integrated weed management provides an authoritative review of the latest developments in IWM. The book covers new research on understanding weed ecology as a basis for more sustainable control, as well as developments in technology to better target IWM techniques. This collection also offers examples of how advances are being applied in practice for particular crops.

Edited by Professor Per Kudsk, Aarhus University, Denmark, Advances in integrated weed management will be a standard reference for weed scientists, researchers in crop protection, agronomists, farmers, companies supplying/manufacturing pesticides, and government and private sector agencies supporting sustainable agriculture.

Key features

  • Summarises the current advances in IWM, such as the use of technology to allow for more informed decision making (e.g. decision support systems (DSS) and sensor technology) 
  • Discusses the challenges continually faced by the sector, including herbicide resistance, invasive species, climate change and how best to deploy the range of non-chemical control methods available 
  • Provides examples of the practical application of IWM and its optimisation in the field on different crops (cereals, vegetables, pasture, grasslands)

Sample content

Not sure what you’re getting if you buy this book? Click on the cover image below to open a PDF and preview pages from the book.  Alternatively, watch our informative video introduction.

 https://www.youtube.com/embed/8HlriyTJ91ohttps://www.youtube.com/embed/ArWZeIk3ZyY

What others are saying…

“With the evolution and spread of herbicide-resistant weeds, as well as the spread of invasive weeds and new weed challenges with climate change, weed management is becoming increasingly problematic. This volume provides information and insight from a group of distinguished experts on new approaches to tackling these problems with integrated weed management. I look forward to its publication.” Professor Stephen O. Duke, National Center for Natural Products Research, University of Mississippi, USA

Table of contentsView/buy chapters

Part 1 Weed ecology
1.Advances in understanding the contribution of weeds to the functioning of agroecosystems: Sandrine Petit, Séverin Yvoz, Alexandre Ploteau, Camille Zuccolo and Stéphane Cordeau Agroécologie, AgroSup Dijon, INRAE, Univ. Bourgogne, Univ. Bourgogne Franche-Comté, Dijon, France;
2.Advances in understanding the dynamics of weed communities in integrated weed management systems: Jonathan Storkey, Sustainable Agriculture Science, Rothamsted Research, UK;
3.Advances in managing arable weed propagules: Bärbel Gerowitt, University of Rostock, Germany; and Barbara Baraibar, University of Lleida – Agrotecnio, Spain;
4.Advances in understanding allelopathic interactions between weeds and crops: Çağla Görkem Eroğlu and Aurélie Gfeller, Agroscope, Plant Production Systems, Herbology in Field Crops, Switzerland; Anna Elizabeth Louw-Gaume, Agroscope, Corporate Strategy, Switzerland; and Judith Wirth, Agroscope, Plant Production Systems, Herbology in Field Crops, Switzerland;
5.Advances in understanding invasive characteristics in weed species: Ahmet Uludağ, Çanakkale Onsekiz Mart University, Turkey; Mehmet Arslan, Erciyes University, Turkey; İlhan Üremiş, Hatay Mustafa Kemal University, Turkey; and Necmi Aksoy, Düzce University, Turkey;

Part 2 Intelligent weed control technologies
6.Modelling the effects of cropping systems on weed dynamics: the trade-off between process analysis and decision support: Nathalie Colbach, AgroSup Dijon, INRAE, Université de Bourgogne, France;
7.Developing decision support systems (DSS) for weed management: Panagiotis Kanatas, University of Patras, Greece; and Ilias Travlos, Ioannis Gazoulis and Alexandros Tataridas, Agricultural University of Athens, Greece;
8.Advanced detection technologies for weed scouting: C. Fernandez-Quintanilla, J. Dorado and J. M. Peña, Instituto de Ciencias Agrarias (CSIC), Spain; and D. Andújar, Centro de Automatica y Robótica (CSIC), Spain;
9.Advances in precision application technologies for weed management: Ran N. Lati, Newe Ya’ar Research Center, Agricultural Research Organization, Israel; Roland Gerhards, University of Hohenheim, Germany; Hanan Eizenberg and Maor Matzrafi, Newe Ya’ar Research Center, Agricultural Research Organization, Israel; Lior Blank, Agricultural Research Organization – Volcani Center, Israel; and Svend Christensen, University of Copenhagen, Denmark;
10.Advances in mechanical weed control technologies: Bo Melander and Margaret R. McCollough, Aarhus University, Denmark;

Part 3 Case studies
11.On-farm implementation of integrated weed management: M. M. Riemens and M. Elings, Wageningen University and Research, The Netherlands;
12.Optimising integrated weed management in narrow-row crops: L. Bonin, ARVALIS-Institut du Végétal, France; R. Leskovšek, Agricultural Institute of Slovenia, Slovenia; C. Moonen, Institute of Life Science, Italy; W. Smith, NIAB, UK; and M. Sønderskov, Aarhus University, Denmark;
13.Integrated weed management in grasslands: Urs Schaffner, CABI, Switzerland; Heinz Müller-Schärer, University of Fribourg, Switzerland; and Andreas Lüscher, Agroscope, Switzerland;
14.Integrated weed management in perennial woody crops: Verónica Pedraza and José Luis González-Andújar, IAS-CSIC, Spain; Victoire Huet and Paul Tuteirihia, NIAB EMR, UK; and Julien Lecourt, Pôle Scientifique des vignobles Bernard Magrez, France;
15.Evaluating the economics of integrated weed management: Pieter de Wolf, Saskia Houben, William Bijker and Koen Klompe, Wageningen Plant Research, The Netherlands;

Editor’s note: If you are interested in purchasing this book go to: Web: www.bdspublishing.com |

IAPPS members receive a 20% discount. The discount code is IAPPS20

E.A. Heinrichs

IAPPS Secretary General

eheinrichs2@unl.edu

For more information contact:

Katherine Lister | Burleigh Dodds Science Publishing

Marketing Executive

Tel: +44 (0) 1223 839365 | Mobile: 07801509992

Katherine Lister katherine.lister@bdspublishing.com

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In this issue:

From the President
75th Anniversary Symposium and Conference
Photo Competition
NZPPS Medal

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


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
https://nzpps.org/events/nzpps-conference-2022/
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
Phone:
 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
Scion
Staphyt Research Ltd
Syngenta Crop Protection Ltd
The New Zealand Institute for Plant and Food Research Ltd
UPL New Zealand Ltd
Zespri International Ltd
ContactsPresident                             
Dr Mike Cripps
AgResearch
Christchurch
Ph: (03) 325 9936
mike.cripps@agresearch.co.nz
 
Vice President
Dr Hayley Ridgway
Plant & Food Research
Christchurch
Ph: (03) 325 9450
Hayley.Ridgway@plantandfood.co.nz

Immediate Past President
Dr Eirian Jones
Lincoln University
Christchurch
Ph: (03) 423 0746
Eirian.jones@lincoln.ac.nz
 
Secretary
Jenny Taylor
PO Box 21839
Henderson 0650
Ph: (09) 8128506
Mob: (027) 477 9821
secretary@nzpps.org
 
Treasurer
Dr Jason Smith
Horteye Ltd
Nelson
Mob: (027) 249 9370
jason@horteye.co.nz
 Journal Editor/
Communications Manager

Dr Ruth Falshaw
Mahana Editing Services
Rotorua
Mob: (027) 380 9839
nzppeditor@outlook.com
 
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Mike Barley
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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.

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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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BCPC’s GM/Biotech Crops Report – April 2022

5th April 2022

  • GM/Biotech Crops Monthly Reports (BELOW) form part of BCPC’s free three-tier Biotech Crops Info service.
  • This service also includes a weekly round-up of news from around the globe – see BCPC Newslink GM Crops section.
  • Plus – Free access database on over 300 GM/biotech products covering 23 crops in the global market visit BCPC’s GM/Biotech Crops Manual – Register here for free access.
  • Already registered? Click here

GM/Biotech Crops Monthly Report April 2022

Lettuce in space

Astronauts that spend a long time in space can suffer from a loss of bone density due to the reduced gravity but now a team at the University of California have developed a genetically-modified lettuce that produces a drug that can offset this loss and that can be grown in space to provide the astronauts with fresh green leaves to eat. Pic: Mel Edwards. Full Story.

Antibiotics on crops

While Europe bans neonicotinoids to ensure no harmful effects to bees, America is spraying apple and pear orchards with streptomycin to control the bacterial disease fire blight. A study has shown that bees exposed to the streptomycin are less active and collect less pollen than those that are not exposed to the antibiotic.
Full Story.

An elixir of youth

Some people try blood transfusions from young people to recapture that youthful zest for life and now a study has produced some evidence supporting that hope. Young mice blood contains packets of chemicals (extracellular vesicles) budded off from dividing cells that, when injected in to old mice, restores grip strength, stamina and motor coordination. Sadly the effect wears off after a couple of months but another injection can restore it.
Full story

BT maize resistant to stem borer attack

An evaluation of BT maize in Uganda has confirmed a reduction of leaf damage and stem attack that has led to yield increases of 30 – 80%.
Full Story.

Salt-tolerant cotton

A relative of Arabidopsis has yielded a trait that can be used to confer salt tolerance to cotton which could allow the crop to be grown on more land but could also boost yields in areas where it is already grown.
Full Story

Herbicide-tolerant tomatoes

Scientists in Korea have used gene editing to alter three enzymes in tomatoes. The benefits of changes to PDS and EPSPS enzymes are unclear but the changes to the ALS enzyme can confer tolerance of ALS herbicides similar to the naturally-occurring tolerance recently introduced in sugar beet.
Full Story

Potato genome decoded

Scientists at the Max Planck Institute and the Ludwig Maximillian University have decoded the entire genome of potatoes and this knowledge is to be used to develop improved varieties for future cropping. The following link takes you to the German text which can be translated by computer.
Full Story

Gene expression imbalance boosts wheat yields

Researchers at Kansas University have found that varying the expression of various genes in wheat can affect the grain size and final yields. This knowledge can possibly be used to optimise yields of new varieties.
Full Story

Control of Fall Army Worm

Pilot studies in Brazil have shown that release of Oxitec’s ‘Friendly’ male army worms can reduce the populations of army worms due to the males carrying a male only trait and that this reduction will help to protect the Bt maize that is grown there from resistance developing in the wild population. It is very target specific and has no effect on other species such as bees.
Full Story

USDA approved gene-edited cattle

The USDA has decided that gene-edited beef cattle that have shorter hair than unedited cattle pose no safety concerns and can be marketed without waiting for a specific approval:
Full Story

Europe approves transgenic maize with stacked traits

The EFSA finds no safety concerns in GM maize with stacked traits for insect resistance and tolerance of glyphosate and glufosinate. This permits the import of these crops but it still does not allow them to be grown in Europe.
Full Story

Stripe rust resistance in wheat

An international team has identified the specific gene that confers resistance to stripe rust in the African bread wheat variety ‘Kariega’ and now this trait can be transferred to other varieties.
Full Story

Gene-silencing for weed control

Colorado University has developed a spray that contains antisense oligonucleotides that penetrate the leaves of the weed Palmer amaranth and silence essential genes in the weed. Palmer amaranth has developed resistance to a number of herbicides but this spray is specific to this weed and has no effect on the crop or non-target organisms.
Full Story

Nutritional Impact of regenerative farming

The University of Washington has compared crops grown on land under regenerative farming management with crops grown on adjacent conventionally farmed land and has shown that the regenerative farming crops have higher levels of vitamins, minerals and other phytochemicals. They don’t give any comparison of the yields achieved though and perhaps the higher levels of vitamins etc are simply due to them being distributed through lower yielding crops.
Full Story

Transgenic sugarcane

Sugarcane with overexpressed sucrose-phosphate synthase has been trialled in Indonesia has shown increased tiller number, height and yield than conventional varieties without affecting bacterial diversity or gene horizontal flow in the soil.
Full Story

Potato virus Y resistance

Researchers in Iran have used gene-silencing techniques to develop potatoes that exhibit resistance to potato Y virus.
Full Story

GM barley trials in the UK

Fertiliser prices have gone through the roof and NIAB in conjunction with Cambridge University at the Crop Science Centre are to trial gene modified and gene edited lines of barley to see if they can improve the nitrogen and phosphorus uptake of the plants and make them less reliant on applied fertilisers. If successful on barley, it could be rolled out to other crops.
Full Story

Palm oil replacement

Palm oil is widely used in many products but the proliferation of palm plantations is responsible for a lot of habitat loss throughout the world. Now a team at Nanyang technological University in Singapore have developed a technique for producing the oil from common microalgae.
Full Story

Corn borer resistant maize

Zhejiang University in China has developed a genetically modified maize that has insect resistant traits and a 5 year study has shown it can give up to 96% reduction in corn borer damage and a 6 – 10% yield increase over conventional varieties.
Full Story

THE LATEST ADDITIONS TO THE  GM/BIOTECH DATABASE ARE:

The latest approvals of biotech crops to report this month:

• GMB151 – soybean tolerant of isoxaflutole herbicide approved for food use in Canada and for environmental use in America

FOR INSTANT ACCESS TO GM BIOTECH MANUAL CLICK HERE (Registration required)

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Biocontrol agent released to fight invasive weed in Australian national park

Source: Xinhua| 2022-03-24 12:47:00|Editor: huaxia

   

CANBERRA, March 24 (Xinhua) — Australia’s national science agency has deployed a biocontrol solution to an invasive weed that poses a major threat to shorebirds including penguins.

A team from the Commonwealth Scientific and Industrial Research Organization (CSIRO) on Thursday released the fungus Venturia paralias into Victoria’s Port Campbell National Park to prevent the spread of the invasive coastal weed sea spurge.

The sea spurge, also known as Euphorbia paralias, is a flowering plant native to Europe, northern Africa and western Asia. It can alter the structure of sand dunes and displace vegetation, disrupting the nesting patterns of shorebirds.

“The weed also has a sap which can cause irritation to animals as well as humans,” CSIRO scientist Gavin Hunter said in a media release.

“Sea spurge grows along Australia’s southern coastline and is a concern for coastal ecosystems. We’re hopeful the biocontrol agent will help reduce the dense weed from penguin nesting sites at Port Campbell, and many other beaches along the coastline where the weed occurs.

“There are many challenges with current methods for removing sea spurge so finding a biocontrol agent for the weed was important to complement existing management strategies of hand pulling and chemical sprays that are very labour intensive, costly, and can not easily be deployed in difficult-to-access beaches,” the release said.

Discovered on the Atlantic and Mediterranean coasts of France, Venturia paralias causes lesions on the stems and leaves of sea spurge plants.

Following extensive tests at the CSIRO’s quarantine facility in Canberra researchers decided it was safe to release into the national park, which is a popular tourist destination due to its penguin population.

“Our research found that the fungus is highly specific toward sea spurge. Based on our results, the fungus was approved by the regulator for release in Australia,” research technician Caroline Delaisse said. ■

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CSIRO scientists develop biocontrol strategy to tackle invasive species

Alex Crowe

By Alex Crowe

March 25 2022 – 1:30pm

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Gavin Hunter and the biosecurity team at CSIRO have been working on the development of a pathogen to control an invasive weed threatening beach birds. Picture: Elesa Kurtz

CSIRO scientists are coming to the rescue of baby penguins this week with a biocontrol agent produced in Canberra on its way to Victoria to save a threatened colony.

Years of research has culminated in the agent being deployed to Australia’s southern coastline, as part of a wider effort to kill an invasive species affecting birds beach nesting.

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The fungus from France will fight sea spurge, a weed introduced from Europe in the 1930s, which has spread right along the south coast from Western Australia and now into NSW.

Growing up to 120 centimetres high, sea spurge can get so dense it makes it difficult for shorebirds to nest. When the plant is damaged, it oozes a latex which is an irritant to both humans and animals, impacting the appeal of Australia’s great tourism asset.

The CSIRO biocontrol team at Black Mountain has collaborated with colleagues in Brisbane, Western Australia and Montpellier in France to import the biocontrol agent from Europe.

A little penguin chick at Port Campbell National Park. Picture: Supplied

Releases have already been made in Tasmania and now the three year trial will begin at London Bridge, a natural offshore arch in Port Campbell National Park in Victoria.

The NSW government will provide funding for the trial as part of its effort to reduce sea-spurge seeds spreading north via ocean currents.

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CSIRO research scientist Dr Gavin Hunter said adult sea-spurge plants produce up to 20,000 seeds and can maintain viability in the ocean for a long period of time.

Dr Hunter said the current “zero tolerance policy” to control sea spurge was manual removal of the plant and the application of herbicide.

“There’s an active management going on in NSW, but any other strategy that can be used to prevent sea spurge coming into NSW is obviously valued, this potentially could represent one of those strategies,” he said.

The fungus has been grown in a petri dish at the CSIRO laboratory in Canberra where it is mass cultured, dried and then sent to community participants to be sprayed on the invasive weed.

At the end of the three year trials in Tasmania and Victoria, it will be decided whether the fungus can be used to tackle sea spurge infestations across Australian beaches.

It is one of several biocontrol strategies the CSIRO currently has in development to combat invasive species, including African boxthorn and flaxleaf fleabane.

Researchers estimate weeds, Australia’s most economically destructive species, cost the economy around $5 billion per year.

Grain growers alone spend more than $2.5 billion per year on weed control, according to the CSIRO.

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Dr Hunter said biocontrol was an effective tool against a growing problem, however, development was arduous, as had been the case with the fungus to tackle sea spurge.

Initial surveys to find pathogens of the plant began in Europe in 2009, he said.

“Those surveys resulted in the collection of a couple of insects and fungal pathogens of sea spurge and one of those agents was a fungal pathogen that showed promise,” he said.

In 2017, funding was secured to transport the candidate from Europe to the quarantine facility in Canberra.

“We went through a two and a half year period of intensive experimentation with the fungal biocontrol agent in our quarantine facility,” he said.

Sea spurge or Venturia paralias has spread right along the coast. Picture: Supplied

“Then we applied to release the agent in Australia as a bio control agent.

“Now we’re kind of really in the end phase of the whole process.”

Dr Hunter said while biocontrol does not offer a silver-bullet solution, it does provide a promising defence against the increased threat of invasive species.

“Due to climate change and due to the increased movement of goods and people across borders, the chance of introducing an inverse organism or an invasive species into Australia is really high,” he said.

“If there are any invasive organisms that do get into Australia, biocontrol is one tool that we can use to mitigate the further spread and impact that invasive plants could have on our environment.”

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Researcher aims to alleviate global hunger by deciphering the molecular ‘language’ of plants

by University of Toronto

rice
Credit: CC0 Public Domain

As a young child spending time on her grandparents’ rice farm in the Philippines, Shelley Lumba grew up understanding the benefits of the Green Revolution—the period in the 1950s and 60s when many technological advances were made in agriculture.

“My grandparents told stories about how we didn’t have enough rice to feed our family, much less sell in the market,” she says. “And the Philippines was facing the same crisis—there wasn’t enough rice to feed the country’s population. Of course, it was hitting the poorest people hardest and it was happening in countries around the world.”

Then, Lumba’s grandparents began growing a hybrid strain of rice—one of the newly developed varieties of cereals that were hardier, more nutritious and produced higher yields. Thanks to the hybrid, Lumba’s grandparents were able to feed their family and had rice leftover to sell.

Today, Lumba is an assistant professor in the University of Toronto’s department of cell and systems biology (CSB) in the Faculty of Arts & Science. She hopes her research will lead to advances in agriculture like those made during the Green Revolution and help alleviate hunger, poverty and climate change.

Lumba and her colleagues study how organisms—even those from completely different kingdoms—communicate on a molecular level through a shared “language of life.” For example, plants signal fungi in the soil by giving off hormones called strigolactones (SLs). These “come-hither” hormones trigger the fungi to latch on to the plant, thus establishing a symbiotic relationship in which the fungi provide phosphates to its partner and, in return, receives carbon.

“This symbiosis is ubiquitous,” says Lumba. “If you’re a gardener, you know that new, sterile soil feels like sand, but soil from your planted pots or garden feels heavy with ‘stuff.’ That stuff is all the different fungi and bacteria helping your plants grow.”

SLs and other plant hormones such as gibberrellins trigger germination when conditions are favorable—for example, when there’s sufficient moisture and nutrients in the soil.

Lumba’s goal is to better understand how, at a molecular level, organisms send out these signals and, once received, how those signals are translated into a response. One hope is that the research will lead to new ways of combatting the blight caused by the parasitic Striga hermonthica, commonly known as witchweed.

Witchweed—aka the “violet vampire” for its bright flowers—is considered by the United Nations to be a major impediment to poverty alleviation in Africa. The parasite attacks major cereal crops such as maize, sorghum, millet, sweetcorn and rice, latching on to their roots and draining the host of moisture and nutrients.

Witchweed is particularly difficult to combat because a single plant is capable of producing up to 100,000 seeds. The seeds are so tiny they resemble dust and a square-meter patch of ground can contain thousands. What’s more, the parasite begins to damage crops even before sprouting above ground—in other words, before farmers even know their crops are under attack.

Witchweed can lead to significant crop losses and can sometimes wipe out entire harvests. Damage to agriculture in Africa caused by the plant is estimated at approximately US$9 billion a year, with infestations affecting the lives of over 100 million people in 25 countries.

Like any parasitic organism, witchweed needs a host in order to survive and so it has evolved seeds that can remain dormant in the ground for decades until they “sense” that a potential victim is nearby. At that point, the seeds germinate and latch on to a host.

https://www.youtube.com/embed/PSHXZf0T5Fw?color=whiteCredit: University of Toronto

There have been attempts to fight this blight. Researchers are trying to develop witchweed-resistant strains of cereal crops. There have also been experiments where empty fields are treated with SLs to trigger “suicide germination” in the seeds contained in the soil, but SLs are prohibitively expensive to make.

Progress is slow in part because the problem exists predominantly in underdeveloped countries and because solutions won’t necessarily be lucrative for the companies that could develop them.

Another hurdle is that experimenting with witchweed in a lab is challenging. Because it is a parasite, there are strict regulations, permissions and protocols required to grow it. Also, because it requires a host to survive, there’s the added challenge of parsing what’s going on with the parasite and what’s going on with the host. Finally, researchers can’t manipulate witchweed genes—a tool typical of any such investigation.

But a major breakthrough out of Lumba’s lab has circumvented the challenges associated with witchweed experimentation.

The seeds of Arabidopsis thaliana—a member of the family that includes mustards and cabbages—remain dormant because of proteins that suppress germination in the absence of adequate moisture and warmth. When conditions are suitable, Arabidopsis seeds produce the hormone gibberellins which breaks down repressors of germination.

As described in a recent paper in Nature Plants, Lumba and her collaborators have found a way to introduce SL receptors from witchweed in Arabidopsis, thereby circumventing the gibberellins requirement that normally kickstarts germination. The result is a strain of Arabidopsis which respond to SLs like witchweed, thereby creating an effective model plant for their experiments.

With a growing understanding of how a seed responds to SLs on a molecular level, Lumba’s research has the potential to lead to alternate strategies for combating the parasite. For example, it could lead to the design of molecules that will trigger suicide germination, but that are cheaper and easier to make than SLs.

It also opens up the possibility of other strategies such as the development of molecules that will shut down the germination process entirely—even in the presence of SLs from a host.

“I’m hopeful the ‘bench-to-field’ time won’t be too long,” says Lumba, “and that there will be new strategies coming up soon based on this work.”

In addition to their research related to witchweed, Lumba and her colleagues are also investigating another question with global ramifications: Why and how do fungi respond to SLs? Eighty percent of plants rely on this symbiotic relationship and enhancing the interaction with beneficial fungi could lead to hardier crops and reduce the need for fertilizers, thus reducing phosphate runoff into water systems and lowering the production of greenhouse gasses.

What’s more, it could increase crop yields, the benefits of which Lumba witnessed as a child.

“I knew from my family’s experience how important agriculture is,” she says. “The potential impact of research like this is huge and can improve the lives of so many. It’s about healthy soil for a healthy planet.”


Explore further

Witchweed—destructive by nature


More information: Michael Bunsick et al, SMAX1-dependent seed germination bypasses GA signalling in Arabidopsis and Striga, Nature Plants (2020). DOI: 10.1038/s41477-020-0653-z

Journal information: Nature Plants 

Provided by University of Toronto 

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Competitive sorghum crops will dent weed invasion

The Land

Bob Freebairn

14 Mar 2022, 5 a.m.

Cropping

Closer row spacing and heavier sowing rates play a vital part of reducing weeds in grain sorghum crops. Closer row spacing and heavier sowing rates generally have little to no detrimental adverse effect on crop yield.

 Closer row spacing and heavier sowing rates play a vital part of reducing weeds in grain sorghum crops. Closer row spacing and heavier sowing rates generally have little to no detrimental adverse effect on crop yield.

Aa

Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a comprehensive and outstanding publication dealing with all control aspects. These include herbicides, with lots of insightful comment, fair but often acknowledging limitation of specific products, as well as the important contribution of agronomic aspects to help combat weeds’ effect on yield.

Contributed by Qld Department of Agriculture and Fisheries research agronomist Michael Widderick, is an important section covering weed suppression by growing a competitive sorghum crop. Research over two years has shown that growing a competitive sorghum crop with increased density and reduced row spacing can significantly suppress growth and seed production of weeds like barnyard grass and Feathertop Rhodes grass.

While trial results were not always consistent, crops sown in 0.5 m rows generally suppressed weeds better than in the more traditional 0.75 and 1.0m row spacing. Increasing sorghum plant density from more traditional 5.0 plants sq/m to 10 plants sq/m also generally contributed to a more competitive crop against weeds.

Different varieties (of those tested) had no impact on suppressing weed growth, suggesting cultivar choice will have a lesser impact on sorghum competitiveness than agronomy. However, the researchers note that impact of cultivar may differ across seasons and locations. Also especially noteworthy, was that at least in favourably growing conditions sorghum at narrow row spacing and increased density, did not have any negative impact on sorghum yield.

Weed control in grain sorghum is important for crop yield, as well as for driving down the soil weed seed bank. A combination approach is important for weed control.

 Weed control in grain sorghum is important for crop yield, as well as for driving down the soil weed seed bank. A combination approach is important for weed control.

Therefore, gains in competitiveness and reduction in weed growth can be achieved without reducing yield. Again the researchers note that rarely will a sorghum crop be grown without herbicides, whether they be residual or knockdown, or a combination of both. Integrating a competitive sorghum crop with herbicides should provide an additive effect on reducing in-crop weed pressures, growth and seed production. Over time, this strategy should deplete the weed seed banks, and reduce their impact on sorghum production.

Also read: Perfect growing season sees great sorghum crops in north-west

A further valuable part of the publication is discussion of the role of Imidazolinone technology in sorghum, developed by Advanta Seeds. Sorghum has well and truly joined the list of crops with varieties that provide tolerance to Imidazolinone (IMI herbicides). Note this is not GMO technology. This technology allows the application of a new range of registered herbicides at recommended rates without causing crop damage.

Intervix (imazamox + imazapyr) is an example of an IMI herbicide. IMI products have broad spectrum activity with variation in the activity of individual herbicides for pre-emergence and post-emergence control. Control of broadleaf weeds post-emergence is normally limited to small weeds and relies to a measure on the effectiveness of crop competition occurring subsequent to application particularly for less susceptible species. While IMI herbicides like Intervix control a wide range of broadleaf and grass weeds it does, like most herbicides, have its limitations like not controlling fleabane or Feathertop Rhodes grass.

Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a valuable reference.

 Grain Sorghum Weed Control Guide, written for Pacific Seeds by nationally recognised weed authority Andrew Summervaille, is a valuable reference.

Excellent tables are presented in the publication that covers aspects like effect of various herbicides on specific weeds. These are detailed in tables for pre-emergent and post emergent. Tables also detail aspects like plant back intervals, application timing, rates per ha, rainfall requirement and the like.

Especially valuable is Andrew Summervaille’s discussions about various herbicide products. He highlights advantages and disadvantages of the various herbicides. Planning for control of difficult weeds, like fleabane, Feathertop Rhodes grass, and even well known weeds like barnyard grass and liver-seed grass that have or are developing resistance to some herbicides, requires carful choice of herbicide and their application.

Further details obtain the booklet via http://www.pacificseeds.com.au/wp-content/uploads/2021/07/Pacific-Seeds-Grain-sorghum-weed-control-guide-_Low-Res.pdf

Next week: Ensuring legumes are a vital part of the pasture mix.

  • Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.

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TAMIL NADU

Commence annihilation of invasive alien plant species immediately, HC tells govt.

Mohamed Imranullah S.

CHENNAI FEBRUARY 28, 2022 20:27 IST

UPDATED: FEBRUARY 28, 2022 20:27 IST

In 2015, the court had ordered the annihilation of exotic species and the restoration of shola forests in the hilly regions of the State.

In 2015, the court had ordered the annihilation of exotic species and the restoration of shola forests in the hilly regions of the State.

It wants pilot project to begin immediately as it has already been 7 years since it passed orders in 2015 

The Madras High Court on Monday asked the State government to immediately commence a pilot project for the eradication of invasive alien plant species such as eucalyptus, wattle and prosopis juliflora, and carry out proper ecological restoration of natural habitats.

A Division Bench of Justices V. Bharathidasan and N. Sathish Kumar commended Environment and Forests Secretary Supriya Sahu for having come up with a draft Tamil Nadu Policy on Invasive Plants and Ecological Restoration (TNPIPER) and making it available in the public domain.

However, not wanting things to remain on paper any longer as it has already been seven years since the court, in 2015, ordered the annihilation of exotic species and the restoration of shola forests in the hilly regions of the State, the judges asked the Secretary to start the work immediately.

They asked her to come back to the court on March 18 and report that the work had begun. She agreed, and assured the court that the work will begin as early as possible. Earlier, she informed the judges that the draft policy was put in the public domain to invite comments.

The opinions of various stakeholders were obtained and, in the second stage, seven teams of forest officials were constituted to visit Kerala, Karnataka, Telangana, Madhya Pradesh, Odisha, Gujarat and Rajasthan to study the practices followed in those States. The teams had already gone there.

The teams were expected to submit their reports to the State government by March 9. Further, Chief Secretary V. Irai Anbu had approved a proposal worth ₹10 crore, and the funds would be released after clearance was obtained from the Union Ministry of Environment and Forests, the Secretary said.

However, ₹6 crore from the National Bank for Agriculture and Rural Development (NABARD) was already available for the eradication of invasive species and restoration of natural habitat, she said. After taking note of her submissions, the judges said the money could be used for the pilot project.

Ms. Sahu also assured the court that the Tamil Nadu Wildlife Crime Control Bureau will start functioning soon, after obtaining the guidance of an expert committee. She said it was a first-of-its-kind initiative taken by the government because of its commitment to the cause.

The judges further asked the Secretary to consider authorising the police as well as customs officials to prosecute offenders under the Wildlife (Protection) Act of 1972, since the law, as it stands today, permits trial courts to take cognisance of prosecution launched by forest officials alone.


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