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Western Farmer-Stockman

Nate LongWFP-nate-log-juniper-control-web.jpg

Junipers on a hillside are controlled through chaining.

Large populations of the tree can negatively impact sage grouse habitat and diminish sustainability of grazing land.

Heather Smith Thomas | Jul 28, 2022

Farm Futures Summit and Boot Camp 2022

Western juniper is a native shrub that grows to tree size, thriving in the Great Basin, which spans most of Nevada, much of Oregon and Utah, and portions of California, Idaho, Wyoming, and Mexico.   

In recent decades, hardy junipers have been dominating vast areas, crowding out other plant species.  Large populations of juniper can negatively impact sage grouse habitat and diminish sustainability of grazing land.

The goal of many rangeland managers has been to restore ecologic balance.  Juniper removal on the Modoc National Forest in California, for instance, is part of an effort to improve sage grouse habitat, but there are many other ecological benefits resulting from removing the encroaching juniper stands.

These trees pull more water from the ground than the surrounding vegetation does, leaving less moisture for the other plants. With loss of understory vegetation in juniper woodlands, there is soil loss and erosion during intense rain storms. They outcompete most other plants; with their efficient root system they consume a lot of water that would have helped the survival of other plants.

Effect on watersheds has been noticed; with increased demand for water by juniper, combined with several years of drought in Northeast California, many springs and streams have dried up.

Removal projects

Kyle Sullivan, District Manager, Soil and Water Conservation District, Grant County, Ore., says there were government projects in earlier years to help ranchers remove juniper; there was funding for mechanical removal—sawing the trees, piling and burning them.  “Logging crews brought equipment to take out the trees, with hand-labor follow-up for the smaller trees,” Sullivan said.

Loggers piled the trees, and after they dried out the landowners burned the piles during winter when there was no risk of fire danger.

“Our Soil and Water Conservation District received grants to try to control juniper with herbicide.  A dozen years ago we did an experiment, cutting incisions into the trunk with a chain saw, then squirted herbicide into the trunk with a spray bottle. But juniper is so bushy that it is difficult to get to the base of the tree,” he said.

The crew tried different herbicides and different concentrations. It was effective for killing the trees, but the time and labor involved didn’t pencil out, economically.  The Forest Service preferred that method, however, because it left the dead trees standing and didn’t tear up the ground or disrupt surrounding vegetation.

A landowner might choose this method, to kill some of the larger trees and keep them from reproducing, but dead trees on the range might be fuel for wildfires.

“If standing trees are limbed high enough, a grass fire might quickly burn through underneath, but many junipers have low branches under the duff which could raise the fire higher off the ground and into the tree itself,” said Sullivan.

Junipers proliferate

“We left a few trees on the landscape to provide shade for livestock and wildlife, but they had to be trees with no berries (seeds).  Juniper trees have genders, and some can have both male and female characteristics.  If a tree isn’t producing berries it doesn’t spread seeds,” he explained.

“We also learned the importance of maintenance after trees are cut/piled/burned, because the seed source is still there.”  The seeds are viable for years, to produce new seedlings.  The problem will re-emerge if you don’t keep after it.

“After you cut them down you may get a new flush of young trees in 7 to 10 years, but you can do periodic controlled burning or remove the young ones, or use herbicide and eventually get rid of most of them.”            

Junipers are tough and hardy, with high survival rate.  If they take over a range or watershed, they can be detrimental.  “Research is still ongoing in central Oregon, looking at the effects of hydrology, and how a canopy of juniper can keep snow from coming to the ground.  This watershed study is providing new information; we realize what an aggressive root system they have.  If there is a high population of junipers, they have a negative effect on the watershed,” he said.

Herbicide pellets can be used for juniper control. Wilburn Ranches in Oregon started using chemical control of juniper invasions on their range pastures a few years ago, with good results. They took photos of trees afterward, showing how it killed them.

Label directions suggest putting one tablet on the ground in the drip zone of the juniper if it is 3 feet tall.  For every additional 3 feet, you add another tablet– up to about 10 feet of tree height.  The pellets can be applied when moisture is sufficient to dissolve them.  The smaller trees tend to die all at once and the larger ones die by degrees until they completely brown and dead.

Cost per tree for this method is lower than using chain saws or heavy equipment, but the herbicide pellets may need to be repeated every 3-4 years to keep juniper contained.  This is another option for people who don’t want to mechanically remove and then burn them.  Ranchers can hike around and distribute the pellets, or do it from horseback while checking cattle, tossing pellets around the outside edges of the junipers. 

Chains and excavators

Sullivan said one method still used in some parts of the West is chaining.  An old ship anchor chain (with huge, heavy links) is secured between two big Cat tractors to mow down the trees.  The heavy chain pulls on the trees and uproots them.

Another method is to tip the juniper tree over with the boom of an excavator.  The machine can then grab it, pick it up and shake the soil off the roots so the trees can be piled easier.  It costs more for this method but has the advantage of uprooting the trees without much damage to the surrounding terrain.  “A machine can also be used to pile them and clean up the area afterward.  This way you get some of the smaller branches that are underneath the soil; they pull up with the tree roots,” he said.

“This is probably one of the more expensive alternatives but leaves a cleaner site.  Depending on your goals, budget, and equipment, one method may be more attractive than another.”

In his region many ranchers use chain saws and cut down the larger trees, then go back later to get the little ones—and pile them all up with machines. 

“We try to keep abreast of research that keeps evolving on the impacts of these plants, and how to deal with them.  Oregon State University has published a number of guidelines with advice on managing western juniper,” Sullivan said.

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India’s Supreme Court mulls impact of green lighting GM crops on peasant woman farm laborers, who will no longer need to hand-weed

Krishnadas Rajagopal | Hindu | December 5, 2022

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Credit: Getty Images
Credit: Getty Images

The [Indian] Supreme Court on [November 30] expressed concern about the plight of thousands of women agricultural labourers in rural areas, traditionally engaged in de-weeding, who will be part of the human cost if the government permits the commercial cultivation of herbicide-tolerant crops such as GM mustard in India.

“In rural areas, women are experts in removing weeds. They are a part of the labour force in agriculture in India. It brings them employment…” Justice B.V. Nagarathna observed orally while hearing challenges against the environmental clearance given to genetically modified mustard by the government.

Justice Dinesh Maheshwari, the lead judge on the Bench, agreed that women were an integral part of the Indian agricultural landscape, from paddy fields to tea estates, across the country.

“They work in knee-deep water in the fields, bending the whole day and working,” Justice Nagarathna said.

Senior advocate Sanjay Parikh, for a petitioner, said the widespread use of herbicide-tolerant crops would encourage farmers to spray chemical weed-killers.

…“The Supreme Court’s own Technical Expert Committee [TEC] had said that these GM crops were not meant for agriculture in the Indian context. They may be suitable in the western context where there are large farms, but not here,” Mr. Parikh argued.

This is an excerpt. Read the original post here

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Hi-tech farming robot sets about to weed parsnip field

The Robotti is an autonomous tractor which navigates with a satellite-guided accuracy of within 2 cm. It uses attachments for farm operations such as seeding, weeding and spraying. The Danish-built robot is being trialled at Frederick Hiam, a Brandon-based fresh produce business with farms in Suffolk and Cambridgeshire. The farms are growing root vegetables including parsnips, potatoes and onions.

Managing director Jamie Lockhart said he wanted to explore mechanised weeding as a way to reduce herbicide use within a ‘more preventative approach to weed control’. “We offered a 40-hectare block as part of the trial,” he said. “The Robotti has drilled [planted] the parsnips on this block and weeded them on several passes. Initially it was about getting confidence in the accuracy and reliability of a fully autonomous system. In this regard the machine hasn’t put a foot wrong and, on several occasions, we left the machine running all night whilst weeding, and the accuracy was perfect.”

Autonomous Agri Solutions will be demonstrating the Robotti machine at the Agri-Tech Week REAP Conference in Cambridgeshire on November 8, 2022.


Source: edp24.co.uk

Photo source: Agrointelli

Publication date: Wed 26 Oct 2022

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Weevil may save Great Britain up to £16.8m a year in management of invasive aquatic fern

by CABI

Weevil may save Great Britain up to £16.8m a year in management of invasive aquatic fern
The invasive aquatic fern Azolla filiculoides. Credit: CABI

A new CABI-led study suggests that a tiny weevil (Stenopelmus rufinasus) has huge benefits in saving Great Britain up to £16.8m in annual management costs of the invasive aquatic fern Azolla filiculoides.

The research, published in the journal CABI Agriculture and Bioscience, estimates that without any biocontrol the expected yearly costs of managing A. filiculoides would range from £8.4m to £16.9m.

The scientists say that the impacts of naturalized S. rufinasus populations on A. filiculoides alone could be expected to reduce management costs to £800,000 to £1.6m a year.

However, they estimate A. filiculoides management costs to be lower still due to additional augmentative releases of the weevil that take place each summer, resulting in annual management costs of £31,500 to £45,800.

Azolla filiculoides, a type of floating water fern, was introduced to Great Britain at the end of the 19th century for ornamental use in ponds and aquaria. But its introduction into the wild has meant it has spread rapidly throughout England and Wales and to a lesser degree, Scotland.

The invasive aquatic fern outcompetes native species by forming a dense covering on the surface of the water. It blocks out light and can also deoxygenate water. A. filiculoides can also block canals, drains and overflows and may lead to an increased risk of flooding. It can affect irrigation systems—both by blocking their water supply and by reducing water quality.

It has been banned from sale in England and Wales since April 2014.

Its specialist natural enemy, S. rufinasus, was first recorded in 1921. It is suspected to have been introduced from America as a stowaway on A. filiculoides. Stenopelmus rufinasus is also reported to be present in numerous additional European countries where A. filiculoides is present.

The study sought to estimate the management cost savings resulting from the presence of S. rufinasus as a biocontrol agent in Great Britain. This includes the value of additional augmentative releases of the weevil made since the mid-2000s, compared with the expected costs of control in the absence of S. rufinasus.

Corin Pratt, lead author and Invasive Species Management Researcher at CABI, said, “The unintentional introduction of the weevil S. rufinasus to Great Britain is estimated to have resulted in millions of pounds of savings annually in management costs for A. filiculoides.

“Additional augmentative releases of the weevil provide further net cost savings, tackling A. filiculoides outbreaks and bolstering naturalized populations.

“The use of herbicides in the aquatic environment is likely greatly reduced due to A. filiculoides biocontrol. Although somewhat climate-limited at present in Great Britain, climate change may result in even more effective biocontrol of A. filiculoides by S. rufinasus.

“This has been observed in warmer regions such as South Africa, where the plant is no longer considered a threat since the introduction of S. rufinasus.”

The scientists conclude by arguing that in the absence of the specialist weevil S. rufinasus, A. filiculoides could be expected to be the dominant aquatic macrophyte in Great Britain. This would require extensive, costly management and likely widespread use of herbicides in the aquatic environment.

They state that the estimated benefit to cost ratio of augmentative S. rufinasus releases to be of 43.7:1 to 88.4:1.

More information: Corin F. Pratt et al, A century of Azolla filiculoides biocontrol: the economic value of Stenopelmus rufinasus to Great Britain, CABI Agriculture and Bioscience (2022). DOI: 10.1186/s43170-022-00136-0

Provided by CABI

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PestNet

Grahame Jackson posted a new submission ‘Risk analysis and weed biological control.’

Submission

Risk analysis and weed biological control.

Authors: W. M. LonsdaleD. T. BrieseJ. M. CullenAUTHORS INFO & AFFILIATIONS

Publication: Evaluating indirect ecological effects of biological control. Key papers from the symposium ‘Indirect ecological effects in biological control’, Montpellier, France, 17-20 October 1999

https://doi.org/10.1079/9780851994536.0185


Abstract

Weed biological control and risk analysis are very powerful tools for land management and decision-making respectively. We explore the application of risk analysis to weed biological control. Recent criticisms of weed biological control have mainly centred on non-target impacts, attacks by the biological control agent on species other than the weed. In ecology, these are direct effects because they involve physical interactions between the species concerned. Indirect effects are those in which the species do not physically interact. In biological control terms, indirect effects include, on the positive side, the increase in pasture production or biodiversity resulting from successful biological control. On the negative side, they include the decline of a native species that had used the weed as habitat. The aim of weed biological control is then to maximize the ratio of desirable indirect effects to undesirable direct and indirect effects. Using a risk analysis approach, we show that the problems of weed biological control are less in the domain of science and more in that of communication and consultation. A well-conceived biological control project would aim for wide consultation to agree on the target weed with the community, so that negative effects are viewed as trivial against the positive ones. It would also use highly specific agents to reduce the risk of undesirable direct effects to a minimum. Lastly, biocontrollers themselves would merely be advisers on the decision to release.


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New Extension website helps solve pest and disease problems

November 10, 2022

CORVALLIS, Ore. – A new Oregon State University Extension Service website provides a trove of science-based solutions for garden pests, weeds and disease problems in one easy-to-navigate place.

The project was shepherded by Weston Miller, an OSU Extension community horticulturist who got the ball rolling six years ago when collaborators expressed interest and provided funds for what would become the Solve Pest and Weed Problems website.

“Our stakeholders – Metro, the East and West Multnomah Soil and Water Conservation Districts and the city of Gresham – challenged OSU to create a user-friendly pest management resource for the public. Part of my job was to figure out the resources Extension has and pull them together in one place,” Miller said.

Solve Pest and Weed Problems focuses specifically on the Pacific Northwest and prioritizes low-risk approaches. Based on feedback, Miller incorporated household pests, invasive plants, pesticide safety and pollinators, as well as pests and diseases.

“We did extensive planning, including community involvement, user testing, feedback from agencies, nonprofits and many more,” Miller said. “We were able to hire a professional to design the website and do graphic design. Gradually, we kept improving it and building on it.”

The peer-reviewed content is presented in categories with information presented below photos. Clicking on the photo takes you to another page that offers information about identification, look-alikes and specific information on control. High-quality, color photos illustrate each subject.

After compiling Extension resources from sources like the Pacific Northwest Pest Management Handbooks, entries are written by Miller with help from Signe Danler, OSU Extension Master Gardener online horticulture instructor, and other OSU experts. The content is peer reviewed by the OSU Department of Horticulture in the College of Agricultural Sciences. Miller edits the content and posts it on the website. More entries will be added in the future.

To provide more information, the website features links to other OSU Extension resources, as well as to other university-level, science-based sources.

“We hope that people both public and private property managers find practical pest management and prevention,” Miller said. “We want people to use it to make informed decisions for their gardens and public spaces.”

To do that, users will find sections on using less pesticides, pesticide safety, organic pesticides and preventive measures like planting in the right place for the size, water needs, exposure and soil for each plant. Using good selection criteria keeps plants healthy and a healthy plant can fend off pests and diseases, Miller said. The hope, he added, is that people will use less pesticides – or if they do, in a safe manner.

Weeds – from both sides of the Cascades and from throughout the state – get attention. Examples include cheatgrass in eastern and western Oregon; pampas grass on the coast; and tree of heaven, a species of concern statewide. The website includes guides about how to manage landscapes without pesticides or herbicides and 20 pages of pesticide safety guidance.

“We’re putting together material that’s not available in one place with such complete information,” Miller said. “We are super grateful to our partnerships in the broader community who were looking to have a durable information service to meet a fairly defined need. I’m proud of what we’ve accomplished.”

About the OSU Extension Service: The Oregon State University Extension Service shares research-based knowledge with people and communities in Oregon’s 36 counties. OSU Extension addresses issues that matter to urban and rural Oregonians. OSU Extension’s partnerships and programs contribute to a healthy, prosperous and sustainable future for Oregon.

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US (IA): Commercial ag weed, insect, plant disease course organized

Iowa State University Extension and Outreach Washington County will host a Commercial Ag Weed, Insect, and Plant Disease Pest Control Management Continuing Instruction Course (CIC) for commercial pesticide applicators Wednesday, November 16, 2022. The program, provided by the ISU Extension and Outreach Pesticide Safety Education Program (PSEP), is available at office locations across Iowa.

The local attendance site is Washington County Extension Building. Pre-registration is required, and walk-ins on the day of the program will only be admitted if the space allows it. The course runs from 9:00 to 11:30 a.m. The registration fee is $35 on or before November 9 and $45 after November 9. To register or to obtain additional information about the CIC, contact Brandi Dawson at the ISU Extension and Outreach Washington County office at 319-653-4811.

The course will provide continuing instruction credit for commercial pesticide applicators certified in categories 1A, 1B, and 1C. Topics covered will include pesticide use and the environment, pesticide labels and comprehension, including restricted entry interval and preharvest interval, and pest management topics.

Certified Crop Adviser (CCA) Continuing Education Units (CEUs) will be offered in this program. Interested participants should bring their CCA number.

Additional information and registration forms for this and other courses offered by the PSEP program can be accessed at http://www.extension.iastate.edu/PSEP

Pre-registration at https://go.iastate.edu/LAJDBZ

Publication date: Fri 4 Nov 2022

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Heightened weed burden could mean growers need to replace inundated crops

24 Oct 2022

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Frontdesk / Arable

As a result of the summer’s prolonged drought, some early-drilled winter wheats are facing a heightened weed burden after the dry conditions have prevented pre-emergence herbicides from working effectively. That’s according to Mike Thornton, head of crop production for agronomy firm ProCam, who urges growers to assess affected fields to determine if the current crop should be retained or sprayed off and re-drilled.

 “Despite being a distant memory, the summer’s dry and hot conditions are still having an effect on the new cycle of cereal crops,” Mr Thornton explains. “Some wheats which were drilled ahead of schedule or on lighter land have suffered from a lack of soil moisture, which has prevented soil-acting pre-emergence herbicides from working to the best of their ability. As a result, some winter cereals are currently facing heightened competition from out-of-control weeds which, in the most severe cases, could threaten the crop’s viability and profitability.”

 Mr Thornton therefore recommends that each field should be assessed on a case-by-case basis to decide if the current crop, or part of it, should be sprayed off and re-drilled, either with a replacement winter crop, or with a subsequent spring crop.

 “Where the weed burden is excessive or contains difficult-to-control competitors such as black-grass, ryegrass and brome, it could be quite an easy decision to make. For example, if grass weeds have made it to the two-leaf stage or beyond, they will be very difficult to control as most contact herbicides have been rendered ineffective by mounting resistance.

 “In the most severe cases, it will make sense to admit defeat sooner rather than later and to write-off the current crop so that weeds can be burned off ahead of a replacement crop being established.”

 For many growers, Mr Thornton says it’s still not too late to get a replacement winter crop into the ground. For others, deferring to a spring-sown cropping strategy might be the better option.

 “In both cases, growers should be aware of the restrictions imposed by certain active ingredients on replacement crops. The best approach is to seek definitive advice from your agronomist and, where necessary, to implement a ‘plan B’ sooner rather than later.”

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Tech TrendsTechnology

Rice farmers to benefit from new herbicide-tolerant rice system technologies

Published October 24, 2022, 7:26 AM

by MB Technews

BASF and Seedworks Philippines Inc. announced the formalization of new licensing agreements for BASF Clearfield® Production System and Provisia® Rice System technologies that will meet the increasing need of direct seeded rice farming method in the Philippines.

Direct seeding – Leyte

Agriculture is not only impacted by climate change, but also responsible for 17%* of total greenhouse gas emissions. Transplanted wet paddy rice farming is a major contributor of field emissions of methane (CH4). The water irrigated fields block oxygen from penetrating the soil, creating ideal conditions for bacteria that are responsible for emitting greenhouse gases.

As part of BASF Climate Smart farming efforts, and in addition to helping farmers control tough weeds, such as resistant grassy weeds and weedy rice, this new licensing agreement between BASF and Seedworks will see both companies working together to develop and commercialize new non-GMO Herbicide Tolerant hybrid rice (direct seeded) systems to increase both productivity and sustainability for rice growers in the Philippines.

“Rice is a primary source of food for us in Asia. There is an estimated 2.4 million rice growers in the Philippines, with a total acreage of 4.8 million hectares and with up to 36%** of rice grown via direct seeded option versus wet paddy. Direct seeded rice uses roughly 50% less water to grow, uses less labor per day compared to wet paddy.” said Simone Barg, Senior Vice President, Agricultural Solutions, Asia Pacific. “With our new partner, Seedworks Philippines Inc., BASF is dedicated to support farmers to decrease their environmental impact and improve farm resilience. Through our innovative rice solutions of Clearfield and Provisia, two herbicide-tolerant seed traits will be introduced to Philippine’s direct seeded rice hybrid systems. By providing an alternative to wet paddy rice, and providing a more advanced option for current direct seeded rice farmers, Filipino rice farmers now gain the benefit of excellent weed control, a reduced footprint of greenhouse gas emissions and a potential increase of their rice crop yield”

Carlos Saplala, President of Seedworks Philippines, Inc. commented that “Food security issue in the Philippines has never been more relevant than today. Helping farmers leverage on this world class technology will not only improve their yields but also their income. We also expect that underutilized areas in the country due to weedy rice will be better maximized through the use of this Clearfield and Provisia technology. This will also redound to helping the current administration’s objective of offering rice at a more affordable price.”

“SeedWorks’ mission is to strive to provide Seed Solutions more than just selling seeds, I am very delighted with this collaboration with BASF bringing in H.T. Tolerant Rice lines, which is in line with our mission. Together we can help the Filipino farmer optimize his cost of cultivation, improve farm productivity and increase his income from the same land. Rice is a staple diet in the Philippines and we are happy that this project is one more step towards addressing the issue of making the Philippines self-sufficient in rice.” said Dr. Venkatram Vasantavada, SeedWorks Philippines, Inc. Chairman and Managing Director of SeedWorks International.

“Farming is the biggest job on earth, and food security is an important topic for the Philippines. Our government, like many other nations, continues in seeking long term solutions for how our growers can increase yields, decrease environmental impact, and enhance farming robustness. BASF’s Clearfield and Provisia rice systems enable more productive and sustainable farming – key levers identified by the United Nations and incorporated in their Sustainable Development Goals. As a leader in agricultural solutions for growers globally, BASF made this a priority and committed to clear and measurable targets to boost sustainable agriculture by 2030. With this licensing agreement and the steps that Seedworks will take to cultivate the hybrids for the Philippine rice industry, we are very optimistic about the future of achieving more sustainable rice farming, with greater weed control, in the Philippines” said Manolo Sambrano, BASF Industry Head, Agriculture -Philippines.

Clearfield and Provisia rice systems by BASF are non-GM crop technologies for rice production developed with traditional plant-breeding techniques. The innovation is best understood as an integration of seed traits and chemistry. The herbicide tolerant traits allow farmers to control a range of weeds through an easy, over-the top application of a targeted ALS-inhibiting herbicide without harming the rice crop. In addition, together they form an integrated weed management tool for farmers and offer farmers a vital tool in fighting weeds, while remaining compatible with no-till methods, that help preserve topsoil. For more information, visit https://agriculture.basf.us/crop-protection/crops/rice.html.

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Mites enlisted to battle weeds

  • By Katie Klingsporn WyoFile.com
  • Oct 6, 2022
  •  0
Hoary cress
Researchers are exploring using mites to combat the spread of whitetop, or hoary cress, an invasive plant that has colonized much of the West.U.S. DEPARTMENT OF AGRICULTURE

The noxious invasive weed whitetop, which has colonized vast tracts of the West, has long confounded landowners and resource managers. Also known as hoary cress, the plant proliferates quickly, has no natural North American predators and is reportedly toxic to cattle in large quantities.

An unlikely warrior has emerged in the whitetop battle: a microscopic mite from Europe that researchers believe can stunt the weed’s growth. This summer, land managers released the mite in Wyoming for the first time.

“We’re really excited about having the mites,” said Dr. Tim Collier, a University of Wyoming associate professor who specializes in biological control of rangeland weeds. “Whitetop is a huge problem in Wyoming.”

Technicians spread mite-infested “galls” — plant deformities caused by feeding mites — on a 3.5-acre piece of state-owned property in Fremont County in May. The hope is that the mites in the galls will spread to live plants and create new galls, which impede growth.

Dr. Jeffrey Littlefield, a research scientist at Montana State University in Bozeman, is a major player in the whitetop mite effort, a collaboration many years in the making that spans the globe.

The plant-stunting gall mite in question, Aceria drabae, hails from northern Greece.

“It’s been known for a number of years and was thought to be a potential bio control agent for whitetop,” Littlefield said.

A biological-control laboratory began transporting the tiny creature to a containment facility at MSU in the mid-’90s, Littlefield said. Over the years of transfer, testing and monitoring, researchers found positive results. The mites produce different galls that prevent the plants from going to seed, Littlefield said. Galls also spread to secondary stems and forced their host plants to divert energy that would otherwise be used to proliferate.

“They can really stunt the plant,” he said.

Littlefield and his team had to secure U.S. Department of Agriculture regulatory approval. The process for approving biological control agents — natural enemies such as parasites, predators or pathogens — is painstaking and comprehensive.

“And that took probably another good six years or so,” Littlefield said.

But that approval gave Littlefield and his collaborators the green light to release the mites on wild whitetop plants, which they first did in Montana in 2019.

The first year they put mites in one Montana site, Littlefield said, they counted 10 gall-infected stems.

“This past year we’ve had well over 6,000 stems,” he said. “We’re finding not only the number of infested stems has increased, but the gall intensity has increased.”

The hope is to slowly grow the program in order to facilitate releases in more of the West and see a slowing or reversal in the weed’s colonizing patterns.

When the mites became available for release, the Wyoming Weed and Pest Control Council wanted in on it. Whitetop has, after all, affected every county in the state, Larry Smith, president of the Wyoming Weed and Pest Council, said in a release.

There are plenty of introduced plants that don’t cause ecological disorder, said Fremont County Weed and Pest District Supervisor Aaron Foster, who chairs the Wyoming Biological Control Steering Committee.

“But some have the advantage of being competitive and can cause havoc,” he said. “And whitetop is one of those.”

Whitetop “has the ability to use that root system to crowd out the surrounding vegetation,” Foster said. “And it grows and it forms these dense monoculture patches. And they just get bigger and bigger and kind of expand, and start pushing out the desirable grasses, the other forbs that are in there that we like, and pretty quick, the dominant plant is whitetop.”

That’s not good for biodiversity, wildlife or agriculture, he said.

The site near Dubois was selected for a few reasons, Foster said. Fremont County has been a longtime and significant contributor to biological control, research and development in Wyoming, he said, and county weed and pest officials already had sites identified and prepared there.

Now that the mites have been released, the next step is to wait, monitor their effect and evaluate whether to distribute them more widely, Foster said.

The project will take years and isn’t expected to eradicate whitetop in Wyoming. But the hope is that it can slow the spread and save money by preventing other, more expensive measures.

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Mites enlisted to battle weeds

  • By Katie Klingsporn WyoFile.com
  • Oct 6, 2022
  •  0
Hoary cress
Researchers are exploring using mites to combat the spread of whitetop, or hoary cress, an invasive plant that has colonized much of the West.U.S. DEPARTMENT OF AGRICULTURE

The noxious invasive weed whitetop, which has colonized vast tracts of the West, has long confounded landowners and resource managers. Also known as hoary cress, the plant proliferates quickly, has no natural North American predators and is reportedly toxic to cattle in large quantities.

An unlikely warrior has emerged in the whitetop battle: a microscopic mite from Europe that researchers believe can stunt the weed’s growth. This summer, land managers released the mite in Wyoming for the first time.

“We’re really excited about having the mites,” said Dr. Tim Collier, a University of Wyoming associate professor who specializes in biological control of rangeland weeds. “Whitetop is a huge problem in Wyoming.”

Technicians spread mite-infested “galls” — plant deformities caused by feeding mites — on a 3.5-acre piece of state-owned property in Fremont County in May. The hope is that the mites in the galls will spread to live plants and create new galls, which impede growth.

Dr. Jeffrey Littlefield, a research scientist at Montana State University in Bozeman, is a major player in the whitetop mite effort, a collaboration many years in the making that spans the globe.

The plant-stunting gall mite in question, Aceria drabae, hails from northern Greece.

“It’s been known for a number of years and was thought to be a potential bio control agent for whitetop,” Littlefield said.

A biological-control laboratory began transporting the tiny creature to a containment facility at MSU in the mid-’90s, Littlefield said. Over the years of transfer, testing and monitoring, researchers found positive results. The mites produce different galls that prevent the plants from going to seed, Littlefield said. Galls also spread to secondary stems and forced their host plants to divert energy that would otherwise be used to proliferate.

“They can really stunt the plant,” he said.

Littlefield and his team had to secure U.S. Department of Agriculture regulatory approval. The process for approving biological control agents — natural enemies such as parasites, predators or pathogens — is painstaking and comprehensive.

“And that took probably another good six years or so,” Littlefield said.

But that approval gave Littlefield and his collaborators the green light to release the mites on wild whitetop plants, which they first did in Montana in 2019.

The first year they put mites in one Montana site, Littlefield said, they counted 10 gall-infected stems.

“This past year we’ve had well over 6,000 stems,” he said. “We’re finding not only the number of infested stems has increased, but the gall intensity has increased.”

The hope is to slowly grow the program in order to facilitate releases in more of the West and see a slowing or reversal in the weed’s colonizing patterns.

When the mites became available for release, the Wyoming Weed and Pest Control Council wanted in on it. Whitetop has, after all, affected every county in the state, Larry Smith, president of the Wyoming Weed and Pest Council, said in a release.

There are plenty of introduced plants that don’t cause ecological disorder, said Fremont County Weed and Pest District Supervisor Aaron Foster, who chairs the Wyoming Biological Control Steering Committee.

“But some have the advantage of being competitive and can cause havoc,” he said. “And whitetop is one of those.”

Whitetop “has the ability to use that root system to crowd out the surrounding vegetation,” Foster said. “And it grows and it forms these dense monoculture patches. And they just get bigger and bigger and kind of expand, and start pushing out the desirable grasses, the other forbs that are in there that we like, and pretty quick, the dominant plant is whitetop.”

That’s not good for biodiversity, wildlife or agriculture, he said.

The site near Dubois was selected for a few reasons, Foster said. Fremont County has been a longtime and significant contributor to biological control, research and development in Wyoming, he said, and county weed and pest officials already had sites identified and prepared there.

Now that the mites have been released, the next step is to wait, monitor their effect and evaluate whether to distribute them more widely, Foster said.

The project will take years and isn’t expected to eradicate whitetop in Wyoming. But the hope is that it can slow the spread and save money by preventing other, more expensive measures.

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