Feeds:
Posts
Comments

Archive for the ‘Control tactics’ Category

Science/AAAS

Nephila-pilipes-on-a-web-2_16x9

Scientists uncover trick to spider’s stealth

You almost never notice a spider descend from the ceiling until it’s right in front of you. Coming down on its silk thread—the dragline—it barely moves or spins. Now, scientists have figured out why. In a study published this month in Applied Physics Letters researchers collected some golden silk orb-weaver spiders (Nephila edulis and N. pilipes, the latter pictured), raised them in the lab, and collected their dragline silk. They used a device that can measure extremely small forces—the torsion pendulum, the same apparatus that Henry Cavendish used to estimate Earth’s mass about 200 years ago—now equipped with image processing capability. All the other fibers they tested—including human hair, metal wires, and carbon fiber—behaved like an elastic material when twisted, just like a rubber band that comes back to its original shape when twisted or stretched. But, the dragline silk underwent permanent molecular deformation upon twisting. This warping rapidly slows down any movements, steadying the spider. The unique arrangement of molecules in dragline silk—rigid structures that help maintain its overall shape, and soft structures that act like a cushion, absorbing any motion—is responsible for this behavior, the authors suspect. The findings could lead to ropes for rescue helicopter ladders or rappelling climbers that don’t throw us into a spin.

Read Full Post »

 

Broad mites in ornamental crops – Part 1: Challenges and treatments

Broad mites can be controlled using insecticides or biological control.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

Photo 1. Broad mite. Photo by Bruce Watt, University of Main, Bugwood.org.

 

Western flower thrips and aphids have long been the most challenging insect pests in greenhouses. More recently, broad mites (Photo 1) have been posing a more serious threat for greenhouse growers. Broad mites are a potential threat to some of the most important Michigan floriculture crops. According to my previous article, “Attention scouts: Crops that are insect “magnets” in the greenhouse,” the top 10 plants that are attractive to broad mites are New Guinea impatiens (Photo 2), zonal geraniums, Thunbergia, Torenia, verbena, Rieger begonias, Scaevola, angel wing begonias, ivy geranium and buddleia.

So, why are broad mites so concerning? Broad mites are concerning because they are microscopic and are very difficult to see with the common 5x to 10x hand lens. You must send samples to a diagnostic lab or contact your local Michigan State University Extension floriculture educator for a positive diagnosis.

In addition, greenhouse scouts and growers usually notice the plant damage after the populations are already very high and the crops are unsalable. Often times, the damage to the upper leaves near the apical meristem is only noticeable 20 to 30 days after they began infesting the crop.

The greatest populations of broad mites when scouting crops are often not on the plants with the greatest amount of damage. By the time the damage is significant, broad mites have moved on to the neighboring plants with “fresh, new, tasty” tissue. Therefore, greenhouse scouts should actually sample the plants adjacent to those with heavy feeding damage.

broad mite damage

Photo 2. Broad mite damage on New Guinea Impatiens. Photo by Heidi Lindberg, MSU Extension.

The following products are recommendedfor broad mites: Avid, Akari, Judo, Pylon, SanMite, and 2% horticultural oil. For growers interested in using biological control, the predatory mite, Amblyseius swirskii (Photo 3), has been shown to be effective against broad mites. However, cuttings and propagules must be free of pesticide residue in order to effectively use biological control for broad mites. Contact your young plant or cutting supplier to learn about the plant’s pesticide history.

a. swirskii

Photo 3. Amblyseius swirskii. Photo by Evergreen Growers Supply.

One study in Belgium showed that using A. swirskii is actually more effective than the standard chemical treatment (Abamectin) in Belgium. When researchers released broad mites (P. latus) on Rhododendron plants, all of the following treatments were more effective than the weekly abamectin spray:

  • Three weekly releases of A. swirskii beginning in April
  • One release of A. swirskii during April
  • One release of A. swirskii during May
  • One release of A. swirskii with the additional food source Artemia during April
  • One release of A. swirskii with the additional food source Artemia during May

Greenhouse growers who are not getting adequate control of broad mites may want to consider a weekly release of A. swirskii. Contact your local biological control specialist or consultant to develop a strategy for preventative broad mite control.

For more information on the location of broad mites in the crop and about an intensive sampling program, read “Broad mites in ornamental crops – Part 2: Scouting and sampling.

The study referenced in this article is: Gobin, B., E. Pauwels, E. Mechant, and J. Audenaert. 2017. Integrated control of broad mites in ornamental plants under variable greenhouse conditions. IOBC-WPRS Bulletin Vol. 124: 125-130.

Related Articles

Read Full Post »

Delta farm press

Boll weevil photo
Mississippi farmers, and others throughout most of the nation’s cotton-producing regions, have saved many millions of dollars by no longer having to battle the boll weevils that had destroyed cotton yields for decades

For nearly a decade, not a single boll weevil in Mississippi

Mississippi is now entering its tenth year free of the boll weevil that cost U.S. producers billions of dollars over the past century.

Hembree Brandon | Jul 11, 2017

As he had done for the past nine years, Farrell Boyd was beaming at the joint annual meeting of the Mississippi Boll Weevil Management Corporation and the Mississippi Farm Bureau Federation Cotton Policy Committee.

“It’s a pleasure for me to echo what I’ve said for the last nine years: Mississippi continues to be boll weevil-free,” said Boyd, who is program manager for the organization. “We’re going into our 10th year and not the first weevil has been caught — which is great! And we’ve gone from over 500 employees during the height of the eradication effort to just five today.”

Royal-Langley

Robert Royal, left, Midnight, Miss., producer/ginner, and James Langley, V&M Cotton Brokers, Yazoo City, Miss., were among those attending the joint annual meeting of the Mississippi Boll Weevil Management Corporation and the Mississippi Farm Bureau Federation Cotton Policy Committee.

Mississippi producers, and others throughout most of the nation’s cotton-producing regions, have saved many millions of dollars by nolonger having to battle the pest that had destroyed cotton yields for decades, he says.

Still, “We’re not letting our guard down — we’re continuing to operate the Mississippi program in a surveillance mode. We have pheromone traps within a mile of every cotton field in the state, and we monitor them throughout the season in case any weevils should slip in on farm equipment coming from the south Texas areas where the eradication effort is still under way.”
SOUTH TEXAS AND MEXICO AREAS REMAIN

Nearly all of the U.S. cotton belt is now weevil-free, Boyd notes. “The only place where weevils still exist is in the Rio Grande Valley bordering Mexico, along the Rio Grande River, and south of Uvalde in the Winter Garden area, which is a reinfestation area. The reinfestation there emphsizes why we have to be so careful — it’s not impossible weevils could reoccur here as a result of being transported in from an infested area. It’s very important that we continue our surveillance program.”

The cooperative program between Mexico, the Texas Boll Weevil Foundation, and APHIS, to provide training and equipment for Mexico has been “very effective” in enhancing the eradication effort in that region, he says. “Unfortunately, they continue to have intermittent problems with drug cartels. A recent report noted that Mexican eradication workers were out of the field several times due to gun battles in the area. That kind of environment makes their eradication effort even more challenging.”Deere picker

deere  picker

Nearly all of the U.S. cotton belt is now boll weevil-free. Only areas in southernmost Texas and across the Rio Grande River in Mexico remain to be eradicated.

But, Boyd says, there has been “significant progress” on both sides of the border. “Through June 12, in the Rio Grande Valley of Texas, they had an 81.4 percent decrease in weevil captures compared to a year ago. In the Mexican program across the river, through June 12 they’d captured 539 weevils, a 91 percent decrease over 2016.”

Both areas have significant increases in cotton acreages this year, he says, which could have an impact on weevil numbers, “but we’re still comfortable that they’re going to achieve eradication. The cooperative effort with Mexico has been a major achievement.”

BUFFER ZONE TO PREVENT REINFESTATION

Starting in 2014, he notes, the National Cotton Council Boll Weevil Action Committee established a buffer zone in the lower Rio Grande Valley to hopefully protect the rest of the cotton belt from weevil intrusion.

“An assessment was levied to fund the buffer zone, and in 2014 each state contributed 50 cents per acre, with 25 cents per acre in years since then. The buffer program will be reevaluated at the end of five years. So far, none of the money collected has been spent because the buffer zone is in the area where the Texas boll weevil eradication is going on, so it hasn’t cost any additional money to maintain the buffer. By the end of this year the fund will have accumulated between $11 million and $12 million, which is about enough to operate the program. So, they’re holding the money in escrow in the event some of it is needed for that.”

Everything is still “looking very promising” for eradication in the lower Rio Grande Valley, Boyd says, “and we’re looking forward to another weevil-free season in Mississippi. We appreciate everyone’s assistance in watching for harvest equipment or other equipment coming into our state from south Texas so we can be sure no weevils sneak in.

Coley Bailey, Jr., Grenada, Miss., producer, and president of the Mississippi Boll Weevil Management Corporation, echoed Boyd’s enthusiasm for the ongoing success of the program: “It’s great to be almost 10 years weevil-free. When I attended my first board meeting we were $60 million in debt; today we’re blessed to be in strong financial condition. But reinfestation could be costly — and we want to do all we can to prevent that from happening.”

Read Full Post »

Human health issues arising from the use of synthetic pesticides and concerns about their environmental toxicity are making lower-risk alternatives increasingly attractive. Biological control agents are living organisms which reduce harmful pest populations. Many people know of the common ladybird, whose larvae feed on aphids, but a wide range or biological control agents – e.g. […]

via CABI scientists shed light on factors affecting the use of biological control — The Plantwise Blog

Read Full Post »

FTF logo

Agrilinks 2

Reaping Rewards With Resilient Rice

Jul 6, 2017 by Ag Team Comments (0)

Rice is an important staple of Southeast Asian diets. Yet the crop is very vulnerable to weather fluctuations like droughts and floods in countries like Cambodia, where rainfall patterns mean farmers typically rely on a single crop annually. Cambodian farmers also largely rely on a few traditional varieties, which take longer to mature and are less adaptable to weather conditions.

The below video from Agrilinks looks at the International Rice Research Institute (IRRI)’s pioneering work to develop a new variety for Cambodian rice farmers.

The variety has been engineered to withstand droughts, and its shorter growth cycle means farmers can plant and harvest three times in a growing season. The result is higher incomes and yields for Cambodian farmers, and a more stable crop of this important dietary staple.

Learn more at http://irri.org.

Read Full Post »

Hort week

Improved labelling needed to aid application of bio-pesticides says researcher

A researcher has called for better labeling to help growers apply bio-pesticides and improve the success rates of integrated pest and disease management programmes.

Dr David Chandler - image:HW
Dr David Chandler – image:HW

Last year, a series of observation trials were conducted as part of an AHDB funded five-year AMBER project to identify management practices that growers could use to improve the performance of biopesticide products within IPDM.

The trials highlighted several opportunities to improve biopesticide performance through changes to application practices, including quantity of product used, quantity of water, target location within the crop and other environmental parameters that could influence performance.

University of Warwick principal research fellow David Chandler said: “It was clear that there was a lack of understanding about how biopesticide efficacy is affected by factors such as population sizes of pests and diseases, environmental factors such as exposure to UVA and B and water volumes.”

He suggested: “More information needs to be given to growers on how to apply biopesticides in practical situations. This could be done through modifications to improve labeling.”

A survey conducted as part of AMBER also found that growers perceived biopesticides to be unreliable.

AHDB crop protection senior scientist Joe Martin said: “We believe this could be in part as a result of incorrect applications. We need to make sure growers are provided with as much knowledge as possible about the optimum conditions required for good performance of each biopesticide in order to identify potential improvements in application.”

Read Horticulture Week’s insight report
on developments in biocontrols here

AHDB knowledge exchange manager Gracie Emeny added: “A key part of AMBER will be sharing knowledge and experience from trials with growers and the industry to improve best practice guidelines.”

AMBER trials will now focus on developing practices that optimise biopesticide performance and will be tested on commercial nurseries. Growers can keep track of these at the Amber Project website, hosted by Warwick Crop Centre.

For plant health alerts go to Horticulture Week’s Pest & Disease Tracker hereHort week

Read Full Post »

SE farm press

Boll Weevil USDA Agricultural Research Service

The weevil: an historical look at the ‘war’ that changed Southern cotton

The boll weevil and its hunger for cotton was powerful enough to forge an unprecedented partnership between farmers, legislators and scientists.

Dominic Reisig | May 18, 2017

The boll weevil is not much to look at – just a grayish, little beetle with an impressively long snout. But this particular beetle, and its hunger for cotton, was powerful enough to forge an unprecedented partnership between farmers, legislators and scientists. And that partnership showed how much can be accomplished when scientists and farmers work together.

What adult boll weevils lack in size they make up for with their larvae’s ability to feed on and destroy cotton. Boll weevils entered the U.S. from Mexico in the late 1800s, when they were first spotted in Texas. By the 1920s they had spread through all of the major cotton-producing areas in the country. The scope of the damage was breathtaking, as were the control efforts thrown at this insect: at one time, one-third of the insecticide used in the U.S. was used to combat boll weevils.

Editor’s Note: This was originally posted on the North Carolina State University website.

In 1903, the chief of the U.S. Department of Agriculture (USDA)

testified before Congress that the insect’s outbreaks were a “wave of evil,” and that afflicted areas in Mexico had abandoned cotton production altogether. Indeed, many scholars agree that the impact was so great on the rural South’s cotton-dependent economy that it was one of the causes of the “Great Migration,” when African Americans moved en masse to the northern U.S. during the early 1900s.Despite the arrival of the boll weevil, cotton production at first actually increased in the U.S., because the price of cotton increased as the boll weevil ran some cotton growers out of business. Cotton production moved in advance of the weevil, creating a boom in cotton plantings in areas that were weevil-free. But as the cotton spread, so did the boll weevil – costing cotton growers billions in revenue.

Declaring War on the Weevil

Then, in 1958, something novel happened. The National Cotton Council of America unanimously agreed, for the first time ever, on a piece of farm legislation. Among other things, that legislation called for cotton research to be expanded – and the boll weevil to be eliminated.

This was an unusual step for many reasons. First, efforts had been made to eradicate insects in livestock before, but no one had ever tried it with a crop pest; this was breaking new ground. Second, this was going to cost a lot of money, which would require the support of the federal government. Third, nobody had yet come up with a way to eradicate the insect. Finally, once eradication began, the eradication process would become a common pool resource. Because of this, cooperation would be vital, given that there would be a temptation for individuals, or whole regions, to get a free ride, relying on the contributions of their neighbors to the eradication effort. So mandatory farmer participation was a must. One by one, each of the challenges were addressed, requiring close collaboration at every step.

Insect eradication was not an entirely new concept. The promoter of eradication was a USDA Agricultural Research Service (USDA-ARS) scientist named Edward Knipling, who had come up with an idea called the sterile insect technique. This technique was pioneered in the 1950s to eliminate screwworm, a parasitic insect pest of cattle. The sterile insect technique relies on flooding the environment with lots of sterile males. Those males then mate with females, but don’t produce any offspring. Knipling now envisioned eradication of the boll weevil, recognizing that it had two chinks in its armor. First, it was an exotic species, which meant that it could be present without some of the parasites and predators that weakened populations in its native Mexico. Second, it was reliant on a single host plant, cotton, which was also not native to the U.S.

Unfortunately, the sterile insect technique bombed. One million sterile boll weevil males were released in a trial. But the sterile males couldn’t compete with their virile wild counterparts and the trial was unsuccessful.

If eradication was going to take place, scientists would have to develop a new method. To that end, the federal government, state governments, and various cotton foundations and associations appropriated millions of dollars to support the research needed to develop the necessary tools for eradication.

For example, Congress funded USDA-ARS laboratories in many states, including one on the campus of Mississippi State University that was critical to creating many of the tools needed for eradication. This support continued through the eradication effort, ensuring that the insect could be eliminated beginning in Virginia and northeastern North Carolina, and moving steadily southward.

But the researchers of eradication faced a significant challenge up front. They knew that, for eradication to be successful, there had to be a very effective method of controlling boll weevils – one with a success rate of close to 100 percent. And that would require a significant leap over the available control techniques.

During the 1950s, controlling boll weevil infestations required multiple applications of very harsh and toxic insecticides (e.g., aldrin, azinphosmethyl, benzene hexachloride, chlordane, dieldrin, toxaphene, malathion, methyl parathion, and parathion). But a separate scientific advance was just around the corner.

New Weapons

In the 1960s, researchers were just beginning to understand the importance of insect pheromones, the chemicals produced by insect species that change behavior of other individuals in the species. USDA-ARS scientists discovered the sex attractant pheromones of the boll weevil – the combination of chemicals that allowed male boll weevils to find female boll weevils. These researchers were able to perfect a synthetic attractant pheromone blend, creating a lure that could be used to trap the amorous boll weevils. This advance would prove to be the linchpin for successful eradication, as weevils could be attracted, trapped, and monitored.

Another major breakthrough was the discovery of a method of control that increased success from 85-90 percent control to 98-99 percent.

Insect development is dependent on temperature, and lower temperatures slow down weevil development and reproduction. Mississippi scientists discovered that, by making multiple insecticide applications at short intervals during the autumn, they could both reduce the last reproductive generation of the weevils and significantly limit the survival of potentially overwintering adults. This was termed the reproduction-diapause control method.

The combination of the pheromone traps and the reproduction-diapause control method meant that, given cooperation on an area-wide basis, the boll weevil might be eradicated. And the pheromone traps cold also be used to confirm whether eradication efforts were successful. This one-two punch was tested in a pilot program in Alabama, Mississippi and Louisiana during the early 1970s. The pilot program couldn’t prove that this approach would eradicate boll weevils, but it was successful enough at reducing population levels that government, industry and research officials opted to proceed with a large-scale approach. This next step involved rolling out two companion trials in the late 1970s: one trial took place in Mississippi using the best known control methods for boll weevil at the time, while another trial tested the reproduction-diapause control method in North Carolina and Virginia.

Cooperation was critical to the North Carolina/Virginia trial. The federal government came through with enough funding to support 50 percent of the trial, while the state of North Carolina agreed to pick up another 25 percent of the cost. And more than three-quarters of North Carolina cotton growers approved of the eradication, agreeing to fund the remaining 25 percent. Meanwhile, a new insecticide had become available, diflubenzuron, which proved to make the eradication even more successful.

After three years, the reproduction-diapause method proved so successful that only one weevil was trapped in the North Carolina/Virginia eradication area. Moreover, this weevil was thought to be left over in a contaminated trap that hadn’t been cleaned properly. Insecticide use plummeted after eradication, but expansion and continuation of the program was not easy. Problems with funding, grower support in new eradication areas, and outbreaks of other pests, resulting from intensive insecticide applications used in eradication efforts – which obliterated beneficial insects that normally kept pests in check – slowed the process However, by 2009, the boll weevil was declared eradicated from all U.S. cotton-producing states, with one exception: Texas, which is the biggest cotton producer in the country.

A Fragile Victory

Which brings us to 2017. Eradication efforts have been stalled at the Texas-Mexico border, largely due to the instability created by illegal drug trafficking. That instability has effectively made large cotton farms in Mexico inaccessible for treatment, creating a welcoming habitat for boll weevil populations to rebound. Another problem in Mexico is the presence of non-cotton plant species that can host boll weevil. Further efforts to limit cooperation across the border, including the proposed border wall, ensure that the boll weevil’s “wave of evil” remains a looming threat. As a result, there is an ongoing battle to keep boll weevils in check in the Lower Rio Grande Valley of Texas, funded by an ongoing annual assessment from cotton-producing states, which is aimed at preventing – and tracking – the spread of boll weevil populations.

But this story also highlights the fact that that the boll weevil has been largely conquered in the U.S., thanks to cooperation among growers, scientists and government officials – and due, in large part, to federal research funding. For example, in the southeastern U.S., a boll weevil has not been captured in a pheromone trap in 14 years. And those federal investments, made across the South, continue to pay dividends in the form of new projects, which are poised to tackle today’s native and invasive insects due to the investments made from boll weevil eradication.

For example, those early investments by state and federal governments created the USDA-ARS research system that is still present today across the southern U.S., including the facility at Mississippi State. This system continues to make a difference for U.S. farms. Research units in areas that still have boll weevil populations are using cutting-edge technologies, such as population genetics and aerial infrared imaging, to track movement of the species and identify potential patches of host plants for destruction. As boll weevils have been slowly eradicated, state by state, these researchers and facilities have shifted research priorities to other issues and pests affecting crop production. No one wants to fight another hundred-year war with a plant pest.

Read Full Post »

Older Posts »