Archive for the ‘Pest control’ Category

Researchers are poised to win the race against rust diseases

A joint US and Australian research team has generated the first haplotype-resolved genome sequences for the rust fungi causing oat crown rust and wheat stripe rust diseases, two of the most destructive pathogens in oat and wheat, respectively.

After using the latest genome sequencing technologies to understand how rust fungi adapt to overcome resistance in crop varieties, scientists from the University of Minnesota, the USDA-ARS Cereal Disease Laboratory, the Australian National University, Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the University of Sydney are releasing results with two publications in mBio, a journal by the American Society of Microbiology.

The work was announced (here) by the University of Minnesota.

“Like humans, rust fungi contain two copies of each chromosome, which makes their genetics much more complicated than other types of fungi,” said Assistant Professor Melania Figueroa from the University of Minnesota. Figueroa co-led the sequencing effort for the oat crown rust fungus P. coronata f. sp. avenae along with Shahryar Kianian, research leader at the USDA-ARS Cereal Disease Laboratory and adjunct professor at the University of Minnesota.

“A key advance of this work is that for the first time, separate genome assemblies were generated reflecting both of the two chromosome copies in the rust.”

In parallel, Postdoctoral Fellow Benjamin Schwessinger and Professor John Rathjen at the Australian National University applied similar approaches to develop an improved genome assembly of the stripe rust fungus, P. striiformis f. sp. tritici. By working together the two teams were able to combine their techniques and knowledge to achieve these breakthroughs much more rapidly than by working alone.

These studies represent a breakthrough in plant pathology as they now show how genetic diversity between the two chromosome copies can influence the emergence of new virulent pathogen strains.

Both studies uncovered a surprisingly high level of diversity between the two copies, suggesting that such variation likely serves as the basis to rapidly evolve new rust strains.

“Reports from growers facing yield losses due to oat crown rust occur during most cropping seasons and the genome assemblies of this pathogen will help us understand the evolution of this pathogen and means to develop more resistant crops,” said Kianian, who coordinates annual rust surveys in the US in order to monitor the pathogen population in oat growing areas.

The oat crown rust genomics study compared two strains from North Carolina and South Dakota with different virulent profiles which were obtained in 2012 as part of the routine USDA-ARS Rust Surveys.

The first author of this publication, Marisa Miller, is the awardee of a prestigious USDA-NIFA Postdoctoral Fellow and recently embarked on a study comparing the genomic composition of oat crown rust strains collected in 1990 and 2015.

“In the last 25 years the population of oat crown rust has gained additional virulences, and we would like to understand how this has occurred. Miller’s work is essential to answering this question,” commented Figueroa.

“Oat crown rust is one of the most rapidly evolving rust pathogens,” explained University of Minnesota Adjunct Professor Peter Dodds of CSIRO Agriculture and Food. “So this work will really help understand how new rust diseases like the highly destructive Ug99 race of wheat stem rust can overcome resistance in crops.”

The publications describing the work in the oat crown rust and wheat stripe rust pathogens, both released in the current issue of mBio, will serve as a framework for future studies of virulence evolution in these pathogens as well as for applying similar approaches to the rust fungi causing many other major crop diseases.

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EPA to consider release of fungus in bid to blunt Chilean needle grass

New Zealand farming’s vulnerability to Chilean needle grass may be reduced if an application to release a rust fungus from Argentina wins approval from the Environmental Protection Authority.

Chilean needle grass is found at some 300 sites in New Zealand, covering around 4,000 hectares. But research suggests up to 15 million hectares may be potentially at risk.

Chilean needle grass is common in Australia and has caused production losses of up to 25 per cent in infested pastures. It displaces other types of grass, but is less palatable and nutritious to stock.

The grass also reduces the sale value of stock. Its sharply pointed seeds bore into the skins of grazing animals, damaging the pelt and reducing carcass value. It can also cause distressing wounds, sometimes blinding lambs and injuring farm dogs.

Marlborough District Council has applied to introduce the rust fungus on behalf of a consortium of regional councils and the Department of Conservation.

The fungus – Uromyces pencanus – infects the leaves of Chilean needle grass and competes with them for nutrients, with debilitating effects. Its spores spread rapidly on the wind.

A year-long study in Argentina found the fungus did not spread to plants other than the target needle grass. Other research suggests there is no direct threat to non-target plants in New Zealand, so no native or ornamental plants would be at risk.

This rust is unlike myrtle rust, which infects a wide range of plant host species within the Myrtaceae family. Myrtle rust arrived accidentally in New Zealand, whereas the introduction of U. pencanus would be intentional for a defined purpose – to control the invasive plant, Chilean needle grass.

The EPA will consider the risks and benefits before any decision is made to release the rust in New Zealand.

Public submissions on this application opened today and will close on 13 March.

Queensland lambing rates burgeon after state-funded building of 5000km of fences

A fence-building spree to keep out wild dogs has created a booming lambing rate in western Queensland.

An extra 213,000 sheep have been recorded in the state flock in the past two years, following the state government’s funding of the construction of 5000km of fencing to keep out wild dogs and other feral invaders.

The region’s lambing rate – the number born per 100 “matings” – has soared from less than 20% to 90%, says the premier, Annastacia Palaszczuk.

She said this would deliver an extra “45 full-time jobs worth $2.5m per year”.

The fencing, funded by $13.2m in state grants, now protects almost 300 western Queensland properties from wild dogs and other feral invaders and stretches along a distance which Palaszcuk said was “the same as a return highway journey from Cairns to Sydney”.

The state government has also loaned Longreach regional council $18m to build another 2500km.

Palaszczuk said the government had gone “way beyond” a 2015 election promise to give $5m in funding over three years to tackle feral animals that threaten farmers, and “as a result we are now seeing renewed confidence in the sheep and wool sector”.

In its report on this project (HERE), The Guardian describes Queensland as a relative minnow in Australia’s $4.8b sheep meat export industry, the world’s largest.

It had only 2.2m of the nation’s 70m flock in 2015 and only 1.4% of its lamb production, according to Meat and Livestock Australia.

UCSB scientists report on the effects of landscape characteristics on insecticide use

The effects of certain landscape characteristics on insecticide use depend on context and crop type, an American study has found.

The research has been reported (HERE) by the University of California – Santa Barbara.

Over the past half century, food production has intensified to meet the growing demand, the UCSB report says. And as agricultural fields have become ever larger, more pesticides are required to enhance yield.

Among increasingly huge spreads of single crops, insects tend to thrive as the landscape leaves little habitat for natural enemies such as birds or other predators. whether this plays out in reality has been difficult to determine scientifically.

Empirical landscape-scale studies of the drivers of agricultural insecticide use have produced ambiguous results and aggregated statistics make it difficult to tease apart the effects of underlying components.

A new study by UC Santa Barbara scientists has overcome that obstacle. Using detailed data from roughly 13,000 fields observed from 2005 to 2013 in Kern County, California, Ashley Larsen and Frederik Noack parsed the different effects of landscape characteristics such as crop diversity, field size and cropland extent on insecticide use. Their findings appear in the Proceedings of the National Academy of Sciences.

“If we are to minimize the negative effects of insecticides on human and environmental health, it is critical to understand if and how we can leverage landscape features to reduce insecticide use,” said lead author Larsen, an assistant professor in UCSB’s Bren School of Environmental Science & Management.

“Unlocking the different landscape components across multiple crops and spatial scales provides a novel understanding of which characteristics are likely to increase or decrease insecticide use for specific crops.”

The analysis by Larsen and Noack, a post-doctoral researcher at the Bren School, demonstrated potentially valuable benefits to crop diversity and to smaller fields. However, these benefits were highly dependent on crop type.

The research showed that while crop diversity reduced insecticide use, its impact was small in comparison to the differences in insecticide use between different crops.

“The choice of crops we produce or the type of crops we eat has a much larger impact on overall insecticide use than do landscape characteristics such as crop diversity or cropland extent,” Noack said.

As surrounding grape crop diversity increased, for example, insecticide use fell by nearly 8 kilograms per hectare.

“Grapes use about 49 kilograms of insecticide per hectare, so an 8 kg reduction is a fairly substantial fraction,” Larsen explained. “For oranges, the reduction is less than 2 kilograms per hectare, which is not significant, and for carrots there is no effect at all.”

Moreover, the investigators consistently found that larger fields use more insecticide.

A huge swath of single crop may serve to meet growing demand, but it also provides an uninterrupted breeding ground for insects, which in turn may promote increased chemical treatment to control the pests.

While many factors are at play, on the ecological side the paper was a big advance because scientists haven’t had this type of fine-scale understanding before, Larsen said. The researchers had been able to show that landscape drivers of agricultural insecticide use are very crop specific.

Landcare team looks into fighting wasps with wasps

Landcare Research scientists are exploring possible biocontrol agents, including a mite, to help control German and common wasps which cost the country’s primary industries around $130 million each year.

The most recent addition to the line-up is Sphecophaga, a species of parasitic wasp whose larvae feed off their host, eventually killing it.

The species was tried as a biocontrol agent against wasps in New Zealand starting in the 1980s, but so far has been established only in a few locations.

Recent research suggests this could have happened because the parasitic wasps were from the wrong region – sourced from Switzerland, Israel and the United States. Victoria University recently discovered New Zealand’s dominate wasp species originate from the UK.

Landcare Research biocontrol scientist Dr Ronny Groenteman said this information was “a key piece of the puzzle”.

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Combined seed treatment to help protect NZ crops is given approval

A new version of an insecticide used to help protect corn, wheat grass and brassica crops has been approved by the Environmental Protection Authority (EPA).

Bayer New Zealand’s Poncho Votivo is a seed treatment that will help control pests that can attack these crops.such as Argentine stem weevil, black beetle, greasy cutworm and parasitic nematodes.

It’s a reformulation of an already approved insecticide called Poncho and is applied to seeds at a treatment plant before they’re sown.

“What’s different about Poncho Votivo is that it contains a lower concentration of the neonicotinoid clothianidin, alongside a soil-dwelling micro-organism called Bacillus firmus. This is found naturally in New Zealand soil but has not been used before as an active ingredient in an insecticide,” says Ray McMillan, EPA’s Acting General Manager of Hazardous Substances and New Organisms.

After weighing the risks and benefits of Poncho Votivo following a public hearing in December 2015, the EPA’s decision-making committee approved its use and set specific controls to manage risks to people and our environment. It means those applying the insecticide must wear protective clothing and adhere to specific restrictions related to the rate, method and timing of application.

Mr McMillan said the combined insecticide had benefits for the New Zealand environment because it treats two types of pest at once and farmers are less likely to need a separate soil treatment.

View decision details and information

 

 

Wasp approved to lead fight against tomato and potato pest

The Environmental Protection Authority has approved a type of parasitic wasp as a biological control agent to combat the tomato potato psyllid (a plant louse), which attacks tomatoes, potatoes, capsicums and tamarillos in New Zealand. Biological control agents are natural enemies of a plant or insect pests, and are released to reduce, control or supress those pests.

The wasp (Tamarixia triozae) will be introduced and released to kill the tomato potato psyllid (Bactericera cockerelli).

The psyllid was first found in New Zealand in 2006 and is known as a pest in several countries, creating a significant impact on plants and crops. The psyllid has three life stages – egg, nymph and adult. Adult females lay eggs on the upper and lower surface of potato, tomato, capsicum and tamarillo plant leaves.

The psyllid nymphs and adults feed on the underside of leaves, leaving the plant stunted and discoloured, with poor or little fruit growth. The psyllid also spreads a bacteria that causes Zebra Chip disease in some crops, like potatoes, which affects crop yields.

The wasp is a psyllid parasitoid which means it attaches to or within a single host, eventually killing it. It is a black, winged red-eyed wasp normally found in North America and Mexico. The wasp lays its eggs on the surface of the psyllid nymphs. The eggs develop into larvae that feed on the nymphs, killing them.

The parasitic wasp will be introduced as part of a pest management programme, in combination with other beneficial insects and chemical control strategies.

The application to introduce the wasp was made by Horticulture New Zealand Inc on behalf of a number of growers’ industry groups under the Hazardous Substances and New Organisms Act 1996.

The EPA received 36 submissions on the application, 32 of them in support, two neither supporting nor opposing, and two opposed.