Fall armyworm has recently been found across northern Australia with the most recent detection a moth in Geraldton, Western Australia. Fall armyworms are voracious feeders and are known eat at least 350 species of plants. While they prefer grasses they will also feed on broadleaf crops such as cotton, vegetables and some tree crops as well as native plants and weeds.

A sweet corn crop in Carnarvon that was slashed due to a heavy fall armyworm infestation

Fall armyworm is in the same family (Noctuidae) as Heliothis (Helicoverpa spp.), cutworms and other armyworms. As such the adult moths and caterpillars can be easily confused with related species. Also like related species, the moths are strong flyers and can cover hundreds of kilometres per day. Newly hatched caterpillars can also disperse on silken threads allow them to blow away from egg mass onto other plants.

Fall armyworm are native to the Americas. In North America moths migrate northward along the east coast as far as Canada during the summer.

They were accidentally introduced to Africa in 2016 and have rapidly spread across that continent. It then spread east to the Indian subcontinent in 2018 and was found in East Asia in 2019. Fall armyworm were first detected in the Torres Strait islands in January 2020 and then quickly spread south in Queensland to Bowen. In March moths were trapped in Darwin and down to Katherine in the Northern Territory. They were confirmed at Kununurra on April 1 and were confirmed in Carnarvon April 28 and then at Geraldton on July 23.

Fall armyworm have an ideal temperature range for development between 23 and 30° C. They have an impressive rate of reproduction with females laying between 1000 and 2000 eggs in their lifetime. In tropical and subtropical areas they have a generation time of 30 days (@ 28° C) which leads to multiple generations per season when food is available. Unlike Heliothis there is no diapause (hibernation of pupae). Fall armyworm are likely to be seasonal pests in southern Australia where temperatures fall below about 10° C and there are frosts.

Identification

Fall armyworm moths in a DPIRD trap, Carnarvon, WA.

Moths are very difficult to identify and are easily confused with moths of other closely related species. It is therefore important that suspected moths be correctly identified by an expert entomologist.

Caterpillars hatch and have light-coloured bodies with large dark heads. As they grow they tend to become darker and develop lengthwise stripes and dark spots. Like other Noctuid caterpillars their colour can vary from light green through to black.

An additional key identification feature on larger caterpillars include:

• inverted ‘Y’ marking on the head area

• pale line along the back

• four small spots in a trapezoid on most segments

• 4 large spots in a square on the 2nd last segment

Large fall armyworm caterpillar showing arrangement of spots.

Fall armyworm showing inverted ‘Y’ between the eyes.

The Queensland Department of Agriculture and Fisheries have this handy guide to help growers and agronomists in taking better photos of caterpillars to enable rapid identification by an expert. Https://www.publications.qld.gov.au/dataset/a34b1124-66be-4d31-9899-49d9b0d1bc03/resource/a9f63d63-2117-4bcc-87b9-f24c2c4bf525/download/caterpillaridentification-takingphotos-24march20.pdf

Monitoring

Early detection and reporting of fall armyworm will assist in the management and protection of crops. A network of pheromone traps is being established across Australia. These traps attract male moths.

A DPIRD trap for monitoring moths, Carnarvon, WA.

If you live in Western Australia, Northern Territory for Queensland and would like to participate in the surveillance program contact your local state Department of Agriculture for more information.

To find out what is involved in a trapping program download the Department of Primary Industries and Regional Development (WA) surveillance trapping training manual.

https://www.agric.wa.gov.au/sites/gateway/files/DPIRD%20Fall%20armyworm%20surveillance-trapping%20training%20manual_1.pdf

Control

Frequent monitoring and early detection are the keys to managing fall armyworm.

Experience in Queensland this year has shown that like other related crop pests focusing on control of small caterpillars is the best approach. Caterpillars that feed in the whorl of maize and sorghum can be protected from insecticides particularly if spray set-ups are not at the optimum. Growers and agronomists need to improve their understanding of band spraying set-ups and how to accurately calculate insecticide rates and application volumes to maximise spray coverage. For more information on this see the GRDC Back Pocket Nozzle Selection guide (https://grdc.com.au/__data/assets/pdf_file/0029/206489/grdc-bpg-nozzle-selection.pdf.pdf)

At time of writing there were 35 insecticide permits for a range of crops including maize, sweet corn, rice, cereals, grain sorghum and millet. Go to the APVMA permit search to find which insecticides you can use (https://portal.apvma.gov.au/permits).

It is likely that insecticide resistance is already present in Australian populations of fall armyworm.

A promising number of parasites, predators and pathogens have already been observed Queensland. Fall armyworm caterpillars will become cannibalistic at higher densities.

Further Resources

Western Australian Department of Primary Industries and Regional Development – This is a very comprehensive set of information on FAW by Dr Helen Spafford, based in Kununurra, WA.

https://www.agric.wa.gov.au/plant-biosecurity/fall-armyworm-western-australia

GRDC fall armyworm information

https://grdc.com.au/resources-and-publications/resources/fall-armyworm

 Queensland Department of Agriculture and Fisheries https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/crop-growing/priority-pest-disease/fall-armyworm

Federal Department of Agriculture

https://www.agriculture.gov.au/pests-diseases-weeds/plant/exotic-armyworm

Food and Agriculture Organisation (FAO)

http://www.fao.org/fall-armyworm/en/

In June 2016 Sally Peltzer & I attended Andina III – a 5 day weed workshop in southern Alberta organised by a range of weedies including the notable Roger Cousens, University of Melbourne and Sonia Graham, a social scientist from the University of NSW.

The workshop was held at the Gladstone Ranch near Pincher Creek, in the eastern foothills of the Canadian Rockies and was attended by 32 ‘natural’ and 'social' scientists, agronomists and consultants, from seven countries. Australians and North Americans made up the bulk of the participants.

 Gladstone Ranch homestead

This was the third Andina workshop, with the first 2 taking place in Yellowstone National Park and Spain. Each conference has had a different theme. The theme for Andina III was “the transdisciplinary approach” to weed research and management and a few social scientists were thrown into the mix.

The general principle behind these get-togethers is to fill a perceived void left by traditional conferences by fostering international dialogue, collaboration and mentoring in a relaxed atmosphere. By spending 5 days together and doing a wide range of activities trust and relationships are built between the participants which will continue into the future once everyone has returned home to their normal lives and jobs.

So what is a "transdisciplinary approach"?

This was an interesting question because we asked “what is the difference between transdisciplinarity and a good research and extension program?” This was discussed at some length, for better or worse over the five days.

Integrative multidisciplinary research is thought to address complex real-world problems addressed systemically rather than as isolated problems.  It involves harnessing scholarly and practical knowledge across many stakeholder groups such as scientists from different disciplines, private sector players, farmers, and extensionists at a range of geographic and political levels e.g. local, regional, landscape-wide.

Some of the participants in a 'break-out' session.

Multiple parties bring:

• a wide range of knowledge to address a complex problem.
• AND a diverse and often conflicting range of interests and views

Normally what happens in research is that researchers concentrate on research directions and objectives and tack on some publicity, such as a dry press release, or ill-planned extension at the completion of the research. This is the old top-down approach to research - we know what’s good for you so you should use our research findings....... and be grateful while you’re at it.

We tried to test the multi-disciplinary approach in southern Alberta by doing a fair amount of pre-workshop communication between workshop members as well as reading up on the issues facing the diverse range of land users in southern Alberta.

For us the most interesting case study we investigated was the Waldron Grazing Cooperative which:

• Is a collection of commercial cattle ranches  (over 16,000 ha) under a single progressive manager
• It is a prime wildlife corridor for bears, cougars, elk, deer, coyote and moose
• Accesses land management funds for projects from Alberta Province and Federal Government, private donors and the co-operative.
• Has an agreement with the Nature Conservancy of Canada to protect the land in a state similar to that prior to white settlement, except running beef instead of bison.
• Makes the Waldron Coop an outlier with other beef ranchers in the area because they are seen as different because of their size and the way they access a range of external funds. This is then seen as the major reason why they can run above district average numbers of beasts and obviously has nothing to do with the pasture and grazing management being practised.
• Has leafy spurge (Euphorbia esula) as its major weed species. Leafy Spurge is a perennial with a spreading root system that isn’t eaten by cattle and has been spreading across North America since the early 1900s.

Mike the Walrond manager’s approach

Mike, manager of the Waldron Cooperative, outlining his approach to range management.

• Manage the grass first and the cattle second because without the grass you can’t fatten the cattle. Mike tries to emulate the grazing patterns of the bison with rotational grazing and lets the perennial grasses seed before winter to maintain species diversity in his pastures. Like in Australia most cattle ranchers set stock their pastures over summer leading to an increased density of leafy spurge, and a decline in species diversity and cattle weight gain.

• To manage the leafy spurge Mike uses a biocontrol agent that is a root-feeding beetle. Many other ranchers have also established this beetle on their leafy spurge infestations while others use an ‘unplanned’ herbicide program in an attempt to contain weed infestations.
• What is different with the Waldron Co-op is that they graze  sheep (leased) on the spurge as well. We were told that the reason why the combination of biocontrol and grazing with sheep works so well was that the sheep disperse biocontrol agent. Interestingly no research has been conducted looking at the influence of defoliation in combination with the root feeding biocontrol. We thought that this is probably the reason why this combination works so well not the dispersal of the beetles. This is an excellent example where a multi-disciplinary approach to a problem would have paid off rather than leaving it to biocontrol specialists.
  
  
  
• It is interesting to note that there also is a VERY negative attitude towards the grazing of sheep in the general ranching community going back to the time when homesteaders moved into the Canadian rangelands leading to ‘range wars’.  
• We thought that if you hate sheep, why not try a combination of slashing and biocontrol?

Unfortunately we did not meet any other ranchers that would be considered “typical”. The ranchers we sat down and discussed a weed management with were all organic beef growers. What all ranchers do seem to like doing is sit on a horse.

Canada has also experienced contraction of provincial agriculture departments with a reduction in production research and extension being available to landholders.

So what did we take home from Andina III?

• Andina is a great opportunity to meet a range of international researchers and get to know them having a great time while you’re at it.
• Multi-disciplinary approaches (which are hard to define – just read the peer reviewed papers on the subject) have merit because a number of the researchers we met did not work with anyone from outside their technical silo. Hmmmm. Several researchers said that they would not look at multi-disciplinary cooperation because it would not progress their career objectives i.e. pump out papers.
• Multidisciplinary teams seem an obvious approach for someone with an extension/research background but was a new concept for a number of the researchers.

If you get the opportunity to attend an Andina workshop it is well worth the effort. The next workshop is in Agentina in January 2018. This time the topic will be fundamental molecular biology through to mathematical modelling. For more information go to http://andina4argentina.weebly.com