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.

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Climate warming promotes species diversity, but with greater taxonomic redundancy, in complex environments2


Climate warming is predicted to alter species interactions, which could potentially lead to extinction events. However, there is an ongoing debate whether the effects of warming on biodiversity may be moderated by biodiversity itself. We tested warming effects on soil nematodes, one of the most diverse and abundant metazoans in terrestrial ecosystems, along a gradient of environmental complexity created by a gradient of plant species richness. Warming increased nematode species diversity in complex (16-species mixtures) plant communities (by ~36%) but decreased it in simple (monocultures) plant communities (by ~39%) compared to ambient temperature. Further, warming led to higher levels of taxonomic relatedness in nematode communities across all levels of plant species richness. Our results highlight both the need for maintaining species-rich plant communities to help offset detrimental warming effects and the inability of species-rich plant communities to maintain nematode taxonomic distinctness when warming occur.

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

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Virginia Tech scientists rally international coalition to stop a pestilent ‘army’

July 13, 2017

A man’s hand holding two larvae next to a damaged corn plant.

A man's hand holding two worms next to a damaged corn plant.
A severely damaged corn plant shown next to two of the fall armyworms responsible for the damage. The pest usually feeds on leaves but during heavy infestations will also eat other parts of the plant, including kernels.

The fall armyworm – devastating to corn in Ethiopia, Tanzania, Kenya, and elsewhere – is subject of an emergency workshop July 14 through 16 in Addis Ababa, Ethiopia, to slow the pest’s advance in Africa and prevent its penetration into Southern Europe and Asia.

A pest native to both North and South America, the fall armyworm first landed in western Africa and reached eastern Africa a year later. The pest has the potential to destroy more than $3 billion in corn throughout Africa and trigger food shortages next year, scientists say.

Virginia Tech’s Muni Muniappan witnessed damage in April in Ethiopia, where he met with struggling farmers.

“The worm is voracious, and it must be controlled soon before the damage spreads,” said Muniappan, an entomologist and director of the Virginia Tech-led Feed the Future Innovation Lab for Integrated Pest Management.

A team of researchers from the lab is partnering with the International Center for Insect Physiology and Ecology in Nairobi, Kenya, to produce the workshop, which gathers stakeholders and experts from five countries (the United States, Ethiopia, Kenya, Niger, and Tanzania) to respond to the threat to the region’s food security.

The United States Agency for International Development, which funds the lab at Virginia Tech, is also sponsoring the workshop, where experts will share techniques with farmers to deploy against the pest.

On the continent less than two years, the fall armyworm has created a path of devastation. Its quick spread and heavy destruction make it difficult to control, leaving farmers few options but to handpick caterpillars off their plants.

The pest’s targets include 80 different plant species, some of which are valuable food crops. Many countries in East Africa experienced a sharp drought last year, which resulted in a humanitarian crisis from which millions of farmers in the region are only now recovering, according to the International Association for the Plant Protection Sciences.

The Integrated Pest Management Innovation Lab team is coordinating research in East Africa seeking ways small-scale farmers can mitigate the pest’s impact. The lab is working to identify biological agents – such as a natural enemy like a wasp – to control the fall armyworm by destroying the pest’s larvae.

Scientists are studying traps made from burlap “gunny sacks” that employ such natural enemies. Other methods under study include establishing plants near rows of crops that can keep the pest contained.

The workshop should allow the Integrated Pest Management Innovation Lab to fine-tune its research objectives, Muniappan said. He also hopes the pest, which can fly hundreds of miles once it transforms to become a moth, can be contained before it becomes widespread.

The Integrated Pest Management Innovation Lab is a project of the Office of International Research, Education, and Development, part of Outreach and International Affairs.

Written by Dana Cruikshank and Stephanie Parker


Development of Powdery Mildew Resistant Tomato via CRISPR-Cas9

In tomato (Solanum lycopersicum), there are sixteen Mlo genes, with SlMlo1 being the major contributor to the susceptibility to the powdery mildew caused by Oidium neolycopersici. Natural loss-of-function slmlo1 mutants are available in tomato, however, introgression of such mutations is a lengthy process. The team of Vladimir Nekrasov from the Sainsbury Laboratory, Norwich Research Park in the UK aimed to generate a transgene-free genetically edited slmlo1 tomato using the CRISPR-Cas9 system.

The team targeted the SlMlo1 locus using the double sgRNA strategy. Transformants were analyzed and eight out of ten tested T0 transformants indicated the presence of mutations. Assays using the powdery mildew fungus revealed that all the generated T0 slmlo1 mutant plants were resistant to the pathogen, while wild-type plants were susceptible.

Furthermore, the slmlo1 mutant plants were morphologically similar to the wild type and also produced harvested fruit weight similar to the wild types. The team named the generated variety Tomelo. This study presents evidence for CRISPR-Cas9 being a highly precise tool for genome editing in tomato.

For more on this study, read the article in Nature.

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.”


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.”

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.”


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.”

Southern times

Fall armyworm threatens livelihoods in Africa


By Sifelani Tsiko

African plant and animal disease experts held a crisis meeting in Harare last week on the spiraling fall armyworm outbreak which is destroying maize crops and posing a major threat to food security and agricultural trade in east, central and southern Africa.

The UN Food and Agriculture Organisation together with the Zimbabwean government, SADC and the International Red Locust Control Organisation for Central and Southern Africa (IRLCO – CSA)  convened the regional technical meeting on transboundary crop pests and animal diseases.

This important meeting was convened to discuss appropriate responses to emerging transboundary crop pests and diseases that are threatening crop and livestock production.

Great emphasis was placed on how to stop the spread of the fall armyworm, a caterpillar that has damaged staple crops in what experts say are the ‘frontline’ states – Tanzania, Zambia, Malawi, Mozambique and Zimbabwe. South Africa has also reported a few incidents while Ghana in West Africa has been affected too. Until 2016, the fall armyworm, was largely restricted to the Americas. In Brazil, where the fall armyworm is endemic, it has been estimated to cost US$600 million a year to control. Africa has been facing outbreaks of the fall armyworm (Spodoptera frugiperda) in the last few years which is different from the African armyworm (Spodoptera exempta).

This pest is new to the region and has its origin in the Americas.

“The pest has damaged maize in a number of countries in the region and appears to be moving into the region in a north to south trajectory,” said Food and Agriculture Organisation (FAO) southern Africa coordinator David Phiri.

“What is of particular concern is that the pest has affected countries that are the main producers of maize, a key staple for most of southern Africa. The governments of affected countries are rightly concerned about the danger posed to agriculture and food security by these new caterpillars.” Experts say the fall armyworm has potential to cause a serious food security problem throughout much of east, central and southern Africa.

Ken Wilson, a professor of ecology at Lancaster University in Britain, told plant and livestock disease experts at the meeting that 10 African countries were affected by the fall armyworm infestation damaging some 124,000 hectares (ha) of crop land between 2016 and February 2017.

He cited IRLCO-CSA, USAID and the media as sources of the data. Countries affected included Nigeria, Benin, Togo, São Tomé and Princípe, Zambia, Malawi, Zimbabwe, Mozambique, Botswana and South Africa.

“There remains so many unanswered questions on the fall armyworm,” said Prof Wilson. “Where did the fall armyworm come from? How does its life-cycle differ from that of the African armyworm? Will it spread and will it persist long-term? How do we control it?

“If it persists, the consequences for Africa will be severe. A regional strategy for this new invasive pest is urgently required. Sharing of information and experiences is critical. We need to do this very well at national, regional and international level.”

According to experts, the fall armyworm has caused widespread damage in all of Zimbabwe’s 10 provinces and the entire southern African region.

Cereal deficits affected the entire region last year as a serious drought ravaged southern Africa. In Zambia, the armyworm is reported to have affected 124,000ha of maize while in Malawi more than 2,000ha of the maize crop was hit by an outbreak of the voracious armyworms. Outbreaks have also been reported in the volatile Buzi and Gorongoza regions in Mozambique.

The voracious pest devours maize and 80 other different types of crops and plants.

Plant experts say in order to combat the spread of the armyworm, the Zimbabwe government requires to strengthen monitoring and surveillance including eliciting the support of community-based armyworm forecasting units in various parts of the country.

They say early detection is key to sound management of the pest. IRLCO-CSA director, Moses Okhoba, hailed the Zambian government for its strong response in the fight against the fall armyworm and the African red locust, which were threatening SADC’s third major maize producer. The Zambian government deployed its air force in control efforts and in addition, has budgeted more than US$400,000 to save its maize crop from damage.

Zimbabwe, Malawi and South Africa have also effected control measures. Control measures have been impossible in Mozambique due to security reasons in the volatile Buzi and Gorongoza region.

Namibia, Botswana and a few other southern African countries have also been on high alert.

Apart from the fall armyworm and the African armyworm, the continent also faces threats from a range of transboundary crop and livestock pests and diseases.

The tomato leaf miner (Tuta absoluta) has caused serious losses and disrupted tomato trade between some countries in the region.

The IRLCO-CSA also warned that the region faces a potential locust outbreak following observed increases in the population of the pest in its traditional breeding areas in Tanzania, Malawi, Zambia, Mozambique and Zimbabwe. The main locust types include the brown locust, African migratory locust, Malagasy migratory locust and the red locust. Zambia spent US$3 million using aerial sprays to combat the pest (fall armyworm) while Brazil, the third largest maize producer globally,  spends US$600 million a year to control the fall armyworm.

In Malawi, the locust destroyed 405ha in under two days at a sugar plantation and the firm spent eight million kwacha (US$11,040) in control efforts. This pushed up cost to US$63/ha to cover plane hire and chemicals. Tomato leaf miner has seen prices of tomatoes rising in Botswana, while food prices due to crop pest attacks increased three-fold in Tanzania, 15-fold in Nigeria and forced a Dangote food-processing plant to shut down.

In the livestock sector, Phiri said, the Highly Pathogenic Avian Influenza (HPAI) H5N8, which has been reported in many areas of the world, mostly in the Northern hemisphere, has broken out in Uganda, killing thousands of migratory wild birds and domestic poultry.

“This transboundary disease poses a serious threat to the poultry industry – a sector upon which millions of people, particularly in rural areas, depend for their livelihood and food and nutrition security,” UN FAO official said.

“Southern Africa is at high risk of the disease due to its position along the migratory pathways of wild birds and the ongoing rainy season provides wetlands around which migratory birds tend to congregate.”

The FAO Emergency Centre for Transboundary Animal Diseases (ECTAD) and EMPRES who have been working with governments and other partners to create awareness and build capacities to respond and to prepare to respond to the disease in the event of an outbreak.

Most SADC countries have repeatedly been attacked by outbreaks such as foot-and-mouth disease and other animal diseases, which threaten livelihoods, food security and public health.

Experts say these diseases have negatively impacted on livestock production and market access and cost governments millions of dollars in control efforts. According to a 1997 study by plant and crop experts, infestation during the mid to late whorl stage of maize development caused yield losses of up to between 15 -73 percent when 55 percent of the plants were infested with the fall armyworm.

FAO estimates that between 20 and 40 percent of global crop yields are reduced each year due to the damage wrought by plant pests and diseases.

Experts to the meeting that ran from February 14 to16, were drawn from 13 African countries. They called for a swift and coordinated response to defeat the crop pests and animal disease that were wreaking havoc on the continent.

“The insects are not going to wait for us to look for resources,” said Okhoba. “They won’t stop, we have to act quickly to prioritise control and prevention.” – Zimpapers Syndication


Ethiopia intensifies efforts to battle the fall armyworm

In collaboration with the Food and Agriculture Organization of the United Nations (FAO) and other development partners, the Government of Ethiopia has intensified efforts to protect major maize growing areas from the ravage of the fall armyworm. The fall armyworm, which first arrived in Africa in 2016, was intercepted on a few hectares of irrigated maize fields in southern Ethiopia in the last week of February 2017. It has now covered about 52 962 hectares in 144 districts in three of the major maize-growing regional states – Gambella, Oromia and Southern Nations Nationalities and Peoples’ Region (SNNPR).

Tazelekew Habtamu, a maize farmer in southern Ethiopia where the insect set foot for the first time in Ethiopia, observed unusual insect pest infestation on his maize farm in the first week of March 2017. He reported the case to a local agriculture extension worker, who facilitated immediate pesticide spraying. “At first, the fall armyworm infestation was huge,” said Tazelekew. “The pesticide spray killed most of the pests. I would have lost my maize plants if I did not use the pesticide. However, some remnants of the fall armyworm are still attacking my maize field.”

The fall armyworm is a migratory insect pest known to cause massive destruction of maize crops under warm and humid conditions in the Americans. In Ethiopia, maize fields planted in belg and meher seasons in the prevailing warm and moist weather conditions provide favorable environment for the insect to multiply massively and spread to more areas. “The weather conditions from March to September in maize growing areas provide fertile ground for the insect to mass multiply and spread easily,” said Zebdewos Salato, Director of the Plant Protection Directorate at the Ethiopian Ministry of Agriculture and Natural Resources. Aided by wind front, the fall armyworm of a single generation can spread quickly as far as 500 km away from its point of emergence.

“We expect the infestation to spread to other regions and cover wider areas in the coming months,” he said. “Many farmers in the regions have already planted maize or will plant in June. As more areas plant maize  it is very likely that the pests will spread to more maize areas including in Afar, Amhara, Benishangul Gumz, Oromia and Tigray. We are working hard to make vulnerable regions aware of the need to prepare for possible fall armyworm infestation.”

“The insect is establishing itself and is expected to remain an economic pest for very long time to come hence we need to put in place a short and long term fall armyworm management and control plan,” said Bayeh Mulatu, National Integrated Pest Management Expert at FAO Ethiopia.

For the current season, pesticides have been recommended, as the infestation is massive. Farmers are being advised to handpick the insect when the infestations are very low or apply contact and systemic pesticides using knapsack sprayers when the infestation is significant to cause economic damage, he said.

Farmers are informed to undertake routine monitoring of their farms and exercise handpicking of larvae, which escape the pesticide. According to recent reports, about 24 000 hectares of maize fields have been sprayed with about 36 000 litres of pesticides, and about 12 600 hectares of land have been covered by handpicking the fall armyworm.

However, the control effort has its own challenge. The Government of Ethiopia allocated nearly USD 2 million to tackle the problem. “With this resource, we purchased pesticide and managed to cover only 44 percent of the total maize field so far infested by the fall armyworm,” Zebdewos said. “Taking into consideration the growing infestation of the insect in the wider regions and the below 50 percent infested are treated using pesticides, it would be a big challenge for the Ethiopian Government to address the problem fully. We have challenges with in carrying out effective fall armyworm monitoring, supply of safety outfits, working spraying equipment and other logistics.” According to Zebdewos, even if the control activities are progressing, the impacts of the pest infestation will negatively affect the production of maize in this year, as it takes time for the affected plants to recover.

The Africa wide meeting on the fall armyworm that was held in Nairobi, Kenya gave the responsibility to FAO to coordinate interventions to bring the fall armyworm problem under control. In addition to funding of USD 52 000, FAO supports the Government’s prevention efforts with expert advice and consultation, and facilitation of field assessments, surveillance and monitoring. In addition, in collaboration with the Desert Locust Control Organization for Eastern Africa (DLCO-EA) and other development partners, FAO is developing a project to derail the insect expansion and mass multiplication so that yield loss could be minimized significantly.

In Ethiopia, about nine million smallholder farmers grow maize on 2 million hectares of land, and 75 percent of the maize produced is consumed family as food. Dry stock is mainly used for animal feed and part as fuel and the rest left to decay and amend soil. Amadou Allahoury, FAO Representative in Ethiopia said, “Millions of Ethiopian farmers rely on maize crop as staple food. The livelihood of these smallholder farmers will be at stake if the threat of the pest is not foiled. As FAO, we will continue providing the needed support to the Government in its efforts to tackle the problem.”