Pesticide use in Australia varies between the states as each state has responsibility and develops the regulations for how they are used. Some commonalities of use evolved during the early 2000s, but it is only recently that all states and territories have mostly brought off-label uses in line with each other as seen in Table 1.

What is off-label use?

Off-label use is the use of an agricultural chemical to address a specific issue that is not covered by the APVMA approved label, or permit issued to ‘persons generally’, excluding vertebrate poisons e.g. 1080.
Note: Victoria alone also has a state-based permit system as well as the APVMA permit system.

Wilful misuse on the other hand represents an active or negligent disregard for all instructions and legal requirements with no consideration of the risks.

Table 1. State Control of use legislation (off-label) in agricultural chemicals (as of May 2022) For more information: https://www.awe.gov.au/agriculture-land/farm-food-drought/ag-vet-chemicals/domestic-policy/haccut

Warning!

Off-label practices do not exclude or override product maximum residue limits, work health and safety or environmental safety. If going off-label the decisions the user must consider include the rate of pesticide; time and frequency of application; the likelihood of residues; and the potential for worker exposure.

‘Off-label use’ does not override Directions for Use ‘DO NOT’ statements on labels and permits such as “DO NOT apply to crops or pastures with clover, lucerne or medics”.

When would I go “off-label”?

Different weed to what is on the label

It is likely the most common “off-label” use would be to treat a weed species that is not on a current herbicide label or permit.

Firstly check whether there is a registration or permit for that weed by going to the APVMA web site and check ‘PubCRIS’ database for registrations and the Permit database for labels. https://apvma.gov.au/node/10831

Sea spurge (Cakile maritima) Port Fairy, Victoria

Only go off-label if there are closely related species on the herbicide label or there is trial data proving how effective the herbicide and rate is on the target species. For example sea rocket (Cakile maritima) is a widespread weed of the southern Australian coast, however there are no herbicides registered for its control and no APVMA permits exist. Being a brassica, it is likely herbicides registered for the control of brassicas weeds such as wild radish (Raphanus raphanistrum) would also be effective.

If we look at 2,4-D amine (625 g/L) there are a wide range of brassica species already on the label. However label restrictions might limit off-label use. For example:

·        DO NOT apply by spray equipment carried on the back of the user i.e. a pressurised backpack sprayer

·        Downwind buffer zones for natural aquatic areas

·        Must be applied as spray droplets no smaller than a VERY COARSE spray quality.

·        Some individual state restrictions might also apply.

Different crop or situation on the label

Only Victoria allows this. The principal reason is that there might be issues with residues in the end product if there are no maximum residue limits set for that active ingredient in that crop/product.

Different application equipment than on the label

This is not allowed in the ACT, NSW and Tasmania.

If you wanted to use different application equipment in those places you would need to apply for an APVMA Permit. However this does not override statements on the label. Using the 2,4-D amine (625 g/L) label as an example you still cannot:

• use a backpack sprayer

• use a vertical sprayer

• use equipment that produces a spray quality finer than VERY COARSE

Tank Mixes

Off-label tank mixes are allowed in all states and territories. However tank mix components used in a situation must:

• be registered/permitted for that situation

• they must be compatible in the tank - for example mixing a grass selective herbicide such as Fusilade® Forte with 2,4-D will reduce the level of grass control. In other situations mixing different formulations causes a precipitation of the herbicide to the bottom of the tank.

• biologically compatible in the weed – when targeting sowthistle (Sonchus spp.) mixing glyphosate with 2,4-D reduces the level of control due to the effect the herbicides have on the sowthistle’s biochemical processes

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/

Australian wine is well known for its quality and reliability and the Australian wine industry are world leaders in innovation and quality control. The maintenance of its reputation increases pressure on the vineyard managers to stay well within the allowed limits for the use of pesticides. As such weed control in vineyards becomes relatively complicated with a limited range of herbicides being used.

Current management strategies have led to increasing levels of herbicide resistance and incidence of hard-to-kill-weeds.

Glyphosate resistant annual ryegrass in vine row

Adding to the limited number of herbicides that are acceptable, under-vine spraying is often left until spring when weeds are large with healthy root systems. Good spray coverage then becomes difficult. Adding issues with sprayer setup then leads to highly variable weed control.

Another complication with wine grape production is the encroachment of suburbia as towns expand and get closer to areas of agricultural production. Residential developments in wine growing areas are also popular, with a mandatory golf course attached. This increases the pressure on Vineyard managers to reduce the risks of pesticides going where they should not.

Close proximity of houses limits vine management options

To put all this in perspective wine grape growers have their fungicide applications well sorted which is understandable because fungal disease has the greatest effect on grape yield and fruit quality in wine grapes. Weeds on the other hand have a much smaller effect on the production of high-quality grapes.

Important factors in high levels of weed control are understanding how different herbicide modes of action work which then determines how they need to be applied to optimise their effectiveness. The questions we need to ask are:

• What kind of target are we aiming at?

• What kind of droplets are most appropriate to hit this target?

• What does the product do once it deposits on the target?

Source: Syngenta

Table 1 the number of spray droplets per square centimetre and per cent area coverage for different pesticide types.

The per cent area coverage is most easily measured using water sensitive paper and the SnapCard® app.

To check what pesticides can be used in wine grape production get the Australian Wine research Institute “Agrochemicals registered for use in Australian viticulture” or commonly known as “the dog book” which is also available as app. https://www.awri.com.au/industry_support/viticulture/agrochemicals/agrochemical_booklet/

 Knockdown herbicides that are permitted for use in wine grape production are listed in Table 2. This table shows the behaviours of the different herbicide modes of action. Glyphosate is highly translocated and therefore very forgiving in application technique whereas paraquat is the opposite. Products like paraquat that are translocated need much higher levels of coverage therefore product rate and application volume are critical for high levels of weed control.

Seedling grasses smaller than 3 leaf make a challenging target so it is important to keep the application volume up to ensure there are enough droplets to hit the target.

Table 2 Knockdown / Non-selective herbicides

A small number of selective herbicides are allowed and often used in the inter row area. Most of these herbicides are poorly translocated and also need good coverage to be effective.

Table 3 Selective herbicides

Soil active (residual) herbicides (Table 4) have a set of characteristics which must be understood the get optimum weed control. For example they work poorly if the soil is dry. Sufficient soil moisture is needed to allow the weeds to absorb the herbicide from the soil water. Also due they work poorly or not at all on emerged plants so need to be applied to bare ground or tank-mixed with a compatible knockdown herbicide. Some managers tend to minimise the use of residuals for these reasons and because there is often a lot of dead plant material under the vine row which will intercept the herbicide.

Table 4 Soil active herbicides

Lower levels of trash under the vines opens options for using soil active herbicides

Because of the limited number of herbicides available for use in vineyards and the increase in herbicide resistance it is essential for vineyard managers to understand the characteristics of these herbicides when developing their weed management plans.

In 2019 Cotton Australia implemented a new system to map sensitive crops and sites using an online system called SataCrop (https://crop.satamap.com.au/)  in partnership with Precision Crop Technologies (PCT). The system was trialled around Emerald, Queensland, during the 2018/19 summer season.

Prior to the SataCrop online system Cotton Australia manually mapped cotton crops each season and posted it on their website. This enabled anyone planning to spray to go online and identify where cotton crops were situated. This system was time-consuming and didn’t capture all of the cotton crops. SataCrop is user-implemented and allows growers and agronomists to map all their own crops and sites that are likely to be sensitive to pesticide drift such as cotton, pulse crops, vegetable crops, grapes and tree crops. Field boundaries can be imported from compatible software or entered manually using the polygon tool. (https://www.youtube.com/watch?v=r6GwBWmjWpc). With SataCrop there is no limit to field size and crop fields have a start (sowing) and estimated harvest date. Straight-line distances can also be measured between the proposed spray job and the down-wind sensitive site.

Screen shot from SataCrop of Yanco, NSW at 15 November, 2019. Orange = Soybean; white = cotton research plots; red = other summer crop - rice research

Why is it important to map sensitive crops?

Mapping sensitive crops and sites gives growers and spray contractors the ability to check where sensitive crops and sites such as beehives and aquaculture might be in their vicinity. Using this information in combination with meteorological forecasts allows spray applicators to minimise the risk of drifting their pesticides onto these areas.

The minimisation of pesticide drift is important to reduce potential crop damage and also the contamination of agricultural produce from pesticides. Contamination of agricultural products is important due to increased awareness by both domestic and international buyers of Australian produce.

Cotton damaged by 2,4-D drift. Image: AGRONOMO

Pesticide maximum residue levels (MRL) in produce are also now being used as non-tariff trade barriers. For example China has no set MRL for glyphosate in feed barley so this can be used to negotiate prices.

Recently Thailand banned the use of glyphosate, paraquat and chlorpyrifos so it is likely this will also affect the MRL for these pesticides on produce they import.

Grain buyers in Australia have also increased their monitoring of pesticides in grain. Monitoring residues is important because it:

·        provides an estimate of the occurrence of residues in products

·        identifies potential problems and indicates where action is required

Australia’s high levels of compliance with Australian and international standards gives us a commercial advantage of being seen as ‘clean and green’.

What other sensitive site mapping systems are?

Western Australia

The Department of Primary Industries & Regional Development (DPIRD) have a webpage (https://www.agric.wa.gov.au/grains/sensitive-sites-western-australia) where sensitive sites such as wine grapes, beehives, aquaculture and organic farms are mapped to potentially prevent unwanted chemical drift Unfortunately this system does not meet modern needs for two reasons. Firstly mapping occurs once a year compared with SataCrop which can be updated at any time by a grower or agronomist. Secondly and probably more importantly most broadacre growers are unaware of its existence.

Screenshot from DPIRD Sensitive Sites page November, 2019.

As they say, if you don’t know about it, does it exist?

Iowa, USA

The Iowa Department of agriculture and land stewardship partnered with non-profit company FieldWatch™ to provide an online registry tool to promote communications between producers of pesticide sensitive crops with pesticide applicators called Driftwatch®. They also have a separate system called Beecheck® (https://www.iowaagriculture.gov/Horticulture_and_FarmersMarkets/sensitiveCropDirectory.asp)

This system has 1500 registered producers with 740 fields totalling 13,400 ha which include commercial vineyards, orchards, fruit and vegetables, commercial nurseries and organic crops. The minimum field size is 0.2 ha.

The future?

While SataCrop is currently paid for by Cotton Australia it would be great to see this system or something similar, being used across the Australian cropping belt. This would enable all pesticide users to reduce the risk of pesticide drift onto sensitive crops and areas. This type of system will be highly complimentary to the current efforts across Australia promoting pesticide drift reduction.

Some industries may be hesitant in having their crop locations and areas openly identifiable to the public or possibly their market competitors however the benefits will outweigh the risks for most producers.

For further information on SataCrop contact Ben Houghton ben@pct-agcloud.com