- Regans Ford
- Frankland River
In mid-June Dan Taylor (DKT Rural Agencies) reported a lot of diamondback moths (DBM) flying around near Meckering.
DBM have been reported to be in low levels in canola crops throughout the Frankland River region with caterpillars causing some damage to canola leaves. Crops are being monitored.
DBM larvae are causing damage (shot holes) to four to six leaf canola near Amelup. The crop will be sprayed.
As part of a GRDC-funded project on DBM surveillance, DPIRD staff have again teamed up with grower groups (Mingenew Irwin Group, West Midlands Group and Liebe Group) and the South Eastern Agronomy Services (SEAR) to undertake widespread surveillance for DBM moths and larvae in focus crops during the season. So far, the project has found low numbers of DBM larvae, and in some cases feeding damage, in canola at: Mingenew, Badgingarra, Regans Ford, Broomehill, Cranbrook, Amelup, Takalarup and Gairdner. Forty-five focus crops throughout the grainbelt will be monitored fortnightly throughout the season, and growers and consultants will be updated through PestFax.
There are concerns over what widespread DBM activity now will mean for DBM prevalence in spring, or if we have mild daytime temperatures during the rest of winter.
DBM caterpillar activity should slow down in cold, wet weather conditions and then ramp up in spring. As spring approaches growers can refer DPIRD’s Seasonal Climate Outlook newsletters for the temperature outlook.
Growers and consultants are advised to monitor for DBM, especially from August onwards, by doing at least four lots of ten sweeps with an insect net at various locations in each crop.
Identifying and managing diamondback moth
DBM caterpillars are pale green, cigar-shaped and up to 12mm in length. They wriggle violently when disturbed and can drop down on a fine thread.
Damage from these grubs appears as chewed leaves, buds and flowers with the leaf chewing ranging from irregular holes in leaves to extensive leaf damage.
DBM caterpillars drop from plants when disturbed, and bashing some plants, especially those with holes in leaves, over an ice cream container is a good initial indication of their presence if you don’t have a sweep net handy.
Canola plants can recover from quite a lot of leaf defoliation early in the season.
DBM are difficult to control because they breed prolifically and insecticide sprays have limited coverage in advanced canola canopies.
Thresholds for pre-flowering canola control are:
- pre-flowering (stressed crop) - 30 or more grubs per 10 sweeps
- pre-flowering (no stress) - 50 or more grubs per 10 sweeps.
DBM thresholds for flowering canola are:
- early to mid-flowering (no stress) - 50 caterpillars or more per 10 sweeps
- mid to late flowering (no stress) - 100 or more caterpillars per 10 sweeps.
For more DBM information refer to:
- DPIRD’s Diagnosing diamondback moth page
- GRDC's Diamondback moth fact sheet
- GRDC’s Managing diamondback moth video.
Article authors: Cindy Webster (DPIRD Narrogin), Dusty Severtson (DPIRD Northam) and Alan Lord (DPIRD South Perth).
- Mount Barker
Lucerne flea have been found damaging tillering wheat north of Mingenew.
Plant pathologist Kylie Chambers (DPIRD) has reported lucerne flea causing damage to her barley trial at Nungarin. They were causing windowing damage to leaf tissue.
Lucerne flea has also been causing patches of damage in a three leaf barley crop near Mount Barker.
The lucerne flea is a Collembolan or 'springtail'. Adult lucerne flea are approximately 3mm in size and green-yellow in colour.
Lucerne flea attack a range of crops and pastures, causing characteristic ‘windowing’ of leaves. They work up the plants from ground level, eating tissue from the underside of the foliage.
Loamy and clay soils are known to support higher populations of lucerne flea than soils with low clay/silt content because the fine clay is required for reproduction.
Lucerne flea have a high natural tolerance to synthetic pyrethroids so avoid insecticides from this group when selecting chemicals to control Lucerne flea numbers. For insecticide information refer to DPIRD’s 2021 Autumn/Winter Insecticide Guide.
For more information about diagnosing and managing lucerne flea, refer to DPIRD's Diagnosing lucerne flea page.
Article author: Cindy Webster (DPIRD Narrogin).
Native budworm are active
Four weeks ago, DPIRD technical officer Dave Nicholson (DPIRD) installed a number of native budworm traps in the northern agricultural region. Over a three week period native budworm moth were captured by traps at: Northampton (53 moths), Mingenew (15), Coorow (8), Tenindewa (3), Eurardy (3) and Yuna (1). Dave also did some sweep netting of the crops in the trapping area and at this stage no caterpillars have been detected. This indicates that these moth flights are probably fairly recent.
This week low numbers of native budworm moths were captured in traps at Mingenew N.E (2 moths), Dalwallinu (1) and Cunderdin (1).
Although the trap numbers are relatively low at this stage the unpredictable nature of the native budworm means larger flights could arrive in the coming weeks.
Dan Taylor (DKT Rural Agencies) reports finding native budworm caterpillars in an early flowering canola crop near Tammin. At the moment, the damage is at a low level with just a few holes being chewed in the leaves.
Given what has happened in recent years with high numbers of native budworm moths arriving earlier than usual in some WA locations and causing significant damage to young crops it would be advisable to monitor crops over the coming weeks for budworm caterpillars, particularly in those areas in the northern and eastern grainbelt closer to the pastoral areas.
Identifying and managing native budworm moths
Native budworm caterpillars vary greatly in colour from green through orange to dark brown. They usually have dark stripes along the body and are sparsely covered with fine bristles.
The adult form of the native budworm is a moth that has rapid, low-level flight that takes a zig-zag path and ends with a dive into a crop or shrubs.
During average spring temperatures it takes about seven days for any native budworm eggs laid on crops to hatch into caterpillars. It then takes a further two weeks for the caterpillars to grow in size to about 5mm when they can then be detected in sweep nets. With cooler temperatures in many areas the caterpillar’s life cycle is likely to take longer than three weeks to reach the size of 5mm.
Native budworm moth flights are often variable and unpredictable but moths generally prefer to land in flowering crops in preference to nearby crops that are yet to flower. Native budworm caterpillars most frequently attack the fruiting parts of plants, but at this time of year the caterpillars will feed on the terminal growth and the developing flowers and leaves.
It is important to correctly identify moths and caterpillars to make the best management decision. Capture a moth or caterpillar then take a clear and close-up photo of the insect. Taking close-up photos of any distinguishing features that it may have, such as hairs or spots on its back, will help our entomologists make a diagnosis. You can then send an identification request via the free PestFax Reporter app or by emailing the PestFax team.
Pesticide options for the control of native budworm can be found in DPIRD’s 2021 Winter Spring Insecticide Guide.
Detailed information on native budworm can be found at DPIRD’s Management and economic thresholds for native budworm.
For more information contact Alan Lord, Technical Officer, South Perth +61 (0)8 9368 3758 or +61 (0)409 689 468.
Article authors: Alan Lord (DPIRD South Perth) and Cindy Webster (DPIRD Narrogin).
Russian wheat aphid activity update and feeding damage
- Lake Grace
- Lake King
- West River
- Mount Madden
Russian wheat aphids (RWA) have been recently found in barley and wheat crops at: Katanning, Broomehill, Lake Grace, Pingrup, Newdegate, Lake King, West River, Mount Madden and Ravensthorpe.
The PestFax team is receiving reports of RWA feeding damage in some barley crops. A typical symptom of RWA feeding damage is visible purpling of leaves. However, if you find purple leaves this does not indicate that RWA colonies are present on those plants.
Entomologist Svetlana Micic (DPIRD) recently found barley plants with purpling leaves in a paddock at Needilup, but out of 10 plants with purpling leaves, only one had a colony of RWA present. Half of the paddock had been sprayed but RWA were well below spray thresholds in unsprayed sections. The paddock will be monitored for yield loss.
The purpling of leaves is caused by RWA injecting salivary toxins during feeding which damages plant chloroplasts. Symptoms appear on plants as early as seven days after feeding which is specific to RWA. In wheat and barley plants, damaged leaf tissue does not recover, however if RWA are not present on the plant, any new growth does not show chlorotic markings and appears as normal.
RWA are typically found at the base and sheath of younger leaves and within leaves curled lengthwise by their feeding. They prefer to feed on the newest leaves of plants and are often found on the last two leaves unfurled. At high densities they can be found on any foliar parts.
RWA adults are only about 2mm long, pale yellowish green with a fine waxy coating. RWA antennae are short, and the siphunculi (sometimes called cornicles) do not extend from the back end. For more information refer to the DPIRD Diagnosing Russian wheat aphid page.
RWA is able to survive under a wide range of temperatures, generation time ranges from approximately 20 days at 10oC, and 9 days at 20oC. Trials by SARDI have found their population doubles every 35 days.
Crop yield loss is influenced by the percentage of tillers with RWA per paddock. A RWA threshold calculator is available on GRDC’s Russian wheat aphid page.
For a list of insecticides registered for use on RWA see DPIRD’s 2021 Winter Spring Insecticide Guide or refer to the Australian Pesticides and Veterinary Medicines Authority (APVMA) products database for all chemical control options available for RWA in grains crops.
Please continue to report any suspect detections of RWA, or RWA damage, by using DPIRD’s PestFax Reporter app.
To read about previous RWA activity reported this season, refer to the 2021 PestFax articles in Issue 8 A variety of cereal aphids are active and Issue 6 Russian wheat aphids have progressed further west.
For more information on RWA, refer to the:
- DPIRD Russian wheat aphid: production pest page
- Cesar Australia Russian wheat aphid identification PestBites video
- GRDC Russian wheat aphid page
- GRDC Just how many Russian wheat aphids is too many podcast.
For more information on Russian wheat aphids, or other aphids, contact Research Scientist Svetlana Micic, Albany on +61 (0)8 9892 8591.
Article authors: Svetlana Micic (DPIRD Albany) and Cindy Webster (DPIRD Narrogin).
Vegetable weevil larvae
Courtney Piesse (Agronomique Services) reports finding vegetable weevil larvae causing extensive feeding damage to a six leaf canola crop near Bannister. Courtney estimated there was about 20-30 weevil larvae per plant. The feeding damage is confined to about 20% of the paddock along a strip near where the crop borders bushland. The crop received a post sowing pre-emergence application of bifenthrin/chlorpyrifos. A border control spray of alphacypermethrin will be applied to the damaged area.
Vegetable weevil larvae are also present in a pasture near Woogenellup. They are not causing any production loss.
Vegetable weevil eggs are laid in autumn and develop into larvae in winter. Capeweed is one of their favoured host plants, but they are also found on canola. They usually move from dying capeweed plants onto canola crops. These larvae live for one to two months feeding on leaves of plants before pupating in the soil. Adults emerge from the pupae and feed until summer when they hibernate under pieces of wood, rock, fallen stubble, etc. until the following autumn when they become active again. They have one generation per year.
Vegetable weevil larvae can be hard to find but are usually seen on the underside of leaves.
Vegetable weevil larvae can be confused with the caterpillars of moth species. They are a yellow to green colour with a flattened slug like legless body and they have a smallish brown head. They can cause significant damage when in high numbers.
Adult weevils are about 10mm long with two short white stripes at an angle on each side of its abdomen. The adult weevils hide under surface debris during the day. Damage from vegetable weevil is usually worst next to paddock edges and bush areas, or parts of the paddock that had capeweed in the previous year.
Pesticide options for the control of vegetable weevil can be found in DPIRD’s 2021 Autumn Winter Insecticide Guide.
For more information on weevils visit DPIRD's:
- Diagnosing weevils in canola page
- 2021 PestFax Issue 3 article Identifying and managing weevils in canola
- Identifying soil beetle pests page.
Insect larvae can be tricky to correctly diagnose sometimes due to their similarities in appearance. Fortunately growers and consultants can use the free PestFax Reporter app to request a diagnosis. Users just need to take clear close up photos of the larva and any plant damage and include any other helpful background information when submitting a report.
Article authors: Alan Lord (DPIRD South Perth) and Svetlana Micic (DPIRD Albany).
2021 winter spring insecticide spray guide is now available
DPIRD’s 2021 winter spring insecticide guide is now available and can be downloaded for free at the department’s Insecticide spray guides for crops in Western Australia page.
This spray guide lists the latest registered chemicals and rates that can be applied to canola, lupin and cereal crops for controlling mature crop insect pests.
The department updates its autumn/winter and winter/spring insecticide spray guides annually to help growers and consultants manage insect pests in crops and pasture.
The spray guides are only a guide and growers still need to read chemical labels before use.
Not all insecticide trade names may be listed, so growers should also check with their retailers for any other registered insecticide options.
To download these spray guides and other useful insecticide information, visit the department’s Insecticide spray guides for crops in Western Australia page.
Article author: Cindy Webster (DPIRD Narrogin).
Barley powdery mildew
- South Stirlings
James Bee (Elders) has reported finding powdery mildew on early sown Rosalind barley near South Stirlings. The crop had a Uniform® seed dressing and will be sprayed with Aviator Xpro® and monitored for further disease progression.
Powdery mildew is also present in barley at Dalyup.
Powdery mildew has distinctive symptoms. Fluffy, white powdery growths (becoming cream-grey with age) of fungal spores can be seen on leaf surfaces. Under severe pressure later in the season on stems and heads.
Powdery mildew is favoured by mild temperatures (15–22°C) and high humidity (in excess of 70%). Dense crop canopies, high nitrogen nutrition and extended periods of canopy humidity are factors that are understood to favour mildew development. Dry and warm weather conditions that result in periods of low canopy humidity and temperatures above 25°C can reduce disease development.
This finding of powdery mildew is a timely reminder to monitor barley crops, particularly susceptible varieties, for early symptoms of infection. Rosalind barley has an intermediate resistance rating (MRMS) to powdery mildew in its adult stage (after flag emergence), however in recent seasons in southern growing regions (Albany and Esperance port zones) a shift in virulence to the MILa resistance gene means that varieties such as Rosalind are showing a susceptible reaction and need proactive management for powdery mildew. For more variety disease ratings refer to the department's 2021 WA Crop Sowing Guide - Barley.
Barley and wheat powdery mildew are host specific and do not cross infect. However this report indicates that seasonal conditions are conducive for disease development of both and monitoring of wheat and barley crops for powdery mildew (and other diseases) should be ongoing, particularly in areas where pre-season green bridge was apparent.
Seed dressing or in-furrow products applied to manage other diseases may provide some degree of protection from powdery mildew.
Registered foliar fungicides can be used to control powdery mildew infection; application early in epidemic development is most effective. For more information refer to the department’s Registered foliar fungicides for cereals in Western Australia page.
Since 2012 barley powdery mildew in WA has exhibited resistance to some DMI fungicide products and as part of a disease resistance management strategy growers should avoid using ‘compromised’ fungicides.
The compromised triazole ingredients flutriafol, tebuconazole (eg. Orius®), triadimefon (eg. Triadimefon 125 EC), epoxiconazole (eg. Opus®) or propiconazole (eg. Propiconazole 500 EC) will have reduced efficacy, and these are not recommended for powdery mildew control. Any use of these actives indicated above will increase the selection pressure on the fungicide resistant strains of powdery mildew.
One way to reduce the resistance development of the pathogen is to use fungicide mixtures with different modes of action. Thirteen compounds from four modes of action (FRAC Code 3, 5, 7 and 11) are registered in Australia for powdery mildew control (see DPIRD’s Registered foliar fungicides for cereals in Western Australia). Fungicides containing both a strobilurin (Group 11) and an uncompromised triazole (Group 3) active ingredient such as azoxystrobin + cyproconazole (Amistar Xtra®), azoxystrobin + epoxiconazole (Radial®, Tazer Xpert®), azoxystrobin + propiconazole (TopnotchTM), pyraclostrobin + epoxiconazole (Opera®) or succinate dehydrogenase (SDHI; Group 7) base, benzovindiflupyr + propiconazole (Elatus® Ace) or prothioconazole + bixafen (Aviator® Xpro®) should have uncompromised activity against powdery mildew. Use one application per season of each of these strobilurin or SDHI based fungicide mixtures as part of a fungicide resistance management strategy within the disease control program. A powdery mildew specific multisite amine (Group 5), spiroxamine (Prosper 500® EC) is also registered.
For more information refer to DPIRD’s Managing barley powdery mildew in the face of fungicide resistance page.
For greatest efficacy, fungicides should be applied before significant levels of disease establish in crop.
If you suspect fungicide resistance in your paddock then researchers at the Centre for Crop and Disease Management (CCDM) would love to hear from you. To get in touch please email email@example.com or firstname.lastname@example.org.
Article authors: Kithsiri Jayasena (DPIRD Albany), Andrea Hills (DPIRD Esperance) and Geoff Thomas (DPIRD South Perth).
- Esperance (Gibson)
Apothecia are continuing to be produced in the DPIRD Sclerotinia sclerotia depots at Geraldton, Miling, Merredin, Northam and Esperance (Gibson).
Plant pathologist Kithsiri Jayasena (DPIRD) has identified Sclerotinia ascospores in spore traps located at Talbot (near York).
So far we have not had any apothecia in our depots at Albany or Woodanilling.
Canola crops sown into or next to 2018, 2019 and 2020 canola paddocks are at increased risk of developing sclerotinia stem rot.
Growers are reminded that the SclerotiniaCM decision support tool is available for use during crop flowering to help growers/consultants determine the likely economic returns from applying fungicide at a specific time during flowering. For more information refer to DPIRD’s SclerotiniaCM decision support tool page.
Several fungicide products are registered for the control of Sclerotinia in canola. Fungicides need to be applied as recommended per product label, and no later than 50% bloom. For more information refer to DPIRD’s Registered foliar fungicides for canola in WA page.
DPIRD’s PestFax service is keen to receive any reports of any other apothecia finds or sclerotinia disease observations as the season progresses.
For information on previous apothecia reports received this season and managing sclerotinia refer to;
- DPIRD’s 2021 PestFax Issue 8 article More sclerotinia apothecia are germinating
- DPIRD’s Managing sclerotinia stem rot in canola page
- GRDC’s Sclerotinia stem rot in canola factsheet.
For more information on Sclerotinia contact plant pathologists Andrea Hills, Esperance on +61 (0)8 9083 1144, Ciara Beard, Geraldton on +61 (0)8 9956 8504 or Kylie Chambers, Northam on +61 (0)8 9690 2151.
Article author: Jean Galloway (DPIRD Northam).
Spartacus leaf tipping
- Hines Hill
- Mt Hampton
Plant pathologist Geoff Thomas (DPIRD) reports finding Spartacus leaf tipping in Spartacus barley crops around Beacon.
Plant pathologist Kylie Chambers (DPIRD) has also reported similar symptoms in Spartacus crops at Hines Hill, Nungarin and Mt Hampton. It is also visible in barley trials near Merredin.
This concurs with recent reports on Twitter of Spartacus leaf tipping symptoms occurring on crops in the northern wheatbelt this season.
Symptoms show as yellow tipped leaves, usually restricted to one or at most two leaves on a plant, in mid-canopy of plants at tillering to stem extension. There is usually a dark discolouration on the yellowed leaf which might be confused with net or spot form net blotch or nutritional deficiency. Affected plants may be either sporadically or commonly distributed throughout a crop and can easily be detected by the distinctive yellow leaves.
These symptoms have been reported in previous seasons in Spartacus crops in WA and the eastern states and appear to occur in a range of crop situations.
Plant pathologist Andrea Hills (DPIRD) has previously reported these symptoms in 2019 on the south coast of WA in the closely related barley variety La Trobe as well.
Laboratory testing has failed to detect a pathological cause of these symptoms and they do not appear to multiply up the canopy of an affected plant or crop. In DPIRD trials where leaf tipping has occurred, fungicide treatment has not changed the incidence or severity of this symptom.
It is unlikely that any intervention is needed in affected crops and plants appear to grow away from the affected leaves during the season.
For more information read Intergrain’s Barley News article Funny things happening in Spartacus CL barley – “Spartacus leaf tipping”.
For more information contact Plant Pathologists Geoff Thomas, South Perth on +61 (0)8 9368 3262, Ciara Beard, Geraldton on +61 (0)8 9956 8504, Kylie Chambers, Northam on +61 (0)8 9690 2151. Kithsiri Jayasena, Albany on +61 (0)8 9892 8477 or Andrea Hills, Esperance on +61 (0)8 9083 1144
Article author: Geoff Thomas (DPIRD South Perth).
White leaf spot in canola
- Hines Hill
DPIRD crop protection staff Geoff Thomas, Andrea Hills, Kylie Chambers and Amber Balfour-Cunningham report finding the canola disease white leaf spot (WLS) in crops near Kalannie, Bencubbin, Nungarin, Hines Hill, Munglinup and Gibson. At Kalannie the infection was evident across the paddock affecting at least 50% of plants, with older leaves most affected.
WLS lesions are small, necrotic, circular to irregular off-white to greyish spots on leaves 1-5mm in diameter often surrounded by a dark brown margin as lesions age. It is not unusual to find WLS in canola.
WLS lesions can be confused with herbicide or physical damage. They can also be confused with blackleg foliar lesions but can usually be distinguished from blackleg by the absence of shiny dark pycnidia within the lesion and the presence of a dark brown margin around the off-white lesion.
As the disease progresses several lesions join together to form large necrotic areas. Severe infection on the leaves during flowering may cause premature defoliation.
Cool (10-15°C) wet conditions favour rapid disease development. The fungus can infect stem and pods later in the season but this is rare in WA.
WLS is usually considered to be of minor economic importance in canola in WA due to its sporadic occurrence and low levels of inoculum, however, tight canola rotations are likely to increase build-up of inoculum. Fungicide is rarely required for this disease in WA.
Miravis® is registered for the management of WLS and Prosaro® is also known to effectively control (when applied as part of a blackleg management regime) but is not registered. For more fungicide information refer to DPIRD’s Registered foliar fungicides for canola in Western Australia page.
For more information see the department's Diagnosing white leaf spot in canola page.
For more information about canola diseases contact Plant pathologist Andrea Hills, Esperance on +61 (0)8 9083 1144.
Article authors: Geoff Thomas (DPIRD South Perth) and Andrea Hills (DPIRD Esperance).
Want to know more about Yellow spot in wheat and the new decision support tool for managing it? Register now to attend DPIRD’s YellowSpotWM webinar.
Date: Thursday 15 July 2021
Time: 9.00 – 9.30am (AWST)
DPIRD research scientists Geoff Thomas and Anna Hepworth will be discussing the following topics:
- Yellow spot in wheat and best management practices
- YellowSpotWM – what it does and how to use it.
There will be time for questions and discussion at the end of the webinar.
After registering you will receive a confirmation email containing information about joining the webinar.
For more information contact Senior research scientist Jean Galloway, Northam on +61 (0)8 9690 2172.