PestFacts Issue 4, 2018 - single page view

Phone microscopes: new tool for insect diagnostics

Over the past few weeks, only isolated reports suggest that pest activity in crops continues to be light. After checking in with regional agronomists, we can report the following recent observations:

On Eyre Peninsula, redlegged earth mite (RLEM), Halotydeus destructor, has been observed in pulses in the Kimba and Port Kenny districts, and lucerne flea, Sminthurus viridis, seen around Lower Eyre in higher populations on heavy soils and in paddocks with recent pasture history. Both RLEM and Lucerne flea are active in the Mid-Upper North in low numbers, and in the Lower South East. True wireworm has damaged a wheat crop in Salter Springs. On the Yorke Peninsula, juvenile common white snails are present following hatching at Warooka and Urania.More slater samples have been received: one of the pill bug, Armidillidium vulgare, in association in bean stubble without visible damage at Mundulla, and some Porcellio species (identity to be confirmed) from the Eyre Peninsula.

To help us provide a representative overview, feel free to contribute your observations of pest and beneficial activity (or lack of activity) in your region! Reports can be submitted online using the PestFacts Map, on twitter @PestFactsSARDI or by contacting us directly: Rebecca Hamdorf p: 08 8429 0682 e: rebecca.hamdorf@sa.gov.au or Kym Perry p: 08 8429 0738 m: 0421 788 357 e: kym.perry@sa.gov.au.  Identification services are free to all subscribers, specimens can be posted in a non-crushable container, or images sent by SMS, Twitter or email.

Update 9th July 2018: all available GoMicro Field Scopes have now been claimed.

Sources: Lou Flohr (Byrne Ag Landmark), Adam Hancock (Elders Naracoorte), Nigel Myers (Landmark Cummins), Shane Oster (Alpha Group), Steve Richmond (Landmark Jamestown), Michael Brougham (Elders).

GoMicro Field Scope
GoMicro Field Scope

Wax on, wax off: distinguishing canola aphids

Cabbage aphid, Brevicoryne brassicae, has been observed on volunteer canola at Kadina and near Cummins. Amongst them, some light green aphids can be found; are they green peach aphid (GPA), Myzus persicae?

Recently, we have received several queries related to identifying green peach aphid among other canola aphid species, which include the cabbage aphid, and the turnip aphid, Lipaphis pseudobrassicae. Green peach aphid rarely reaches densities high enough to cause direct economic damage, but can transmit plant viruses in some years, though climatic conditions suggest a low risk in 2018 (see PestFacts Issue 3, 2018). Insecticide resistance is also widespread in Australian green peach aphid populations. For these reasons, correct identification of aphids is important when considering management.

Typically, cabbage aphids are very distinct with their heavy coating of whitish wax, however without this wax, they are green in colour and can look similar to GPA. Aphids typically undergo 3-4 moults during their lifecycle. Moulting removes the cabbage aphid’s waxy coating and immediately after moulting, they appear noticeably green until covered in wax again (wax is produced by the cornicles, or `exhaust pipes`). While cabbage aphid colonises look greyish in colour, turnip aphid colonies have less wax and look greenish in colour. Cabbage aphid and turnip aphid do not typically occur together in the same colonies, but GPA can co-occur with either species.

The following features can be used to distinguish GPA from other `green-looking` canola aphids:

Tubercules are structures on the tip of the head, visible from above.GPA has distinctive, prominent `tubercules` that clearly point inwards, while cabbage and turnip aphids have less prominent, outward-facing tubercules. Cornicles (`exhaust pipes`) are wax-producing structures on the abdomen. GPA has relatively long cornicles that reach the tip of the abdomen, which are swollen with dark-coloured tips. Both cabbage and turnip aphid have shorter cornicles than GPA – in cabbage aphid they clearly do not reach the tip of the abdomen. Turnip aphid also has a difference in colour from the other species – the adults and later instars have dark-coloured bars across their abdomen.

Feel free to contact PestFacts to confirm identification of these aphid species or any pest or beneficial invertebrate.

Source of Reports: Zack Zweck (AW Vater & Co) and Nigel Myers (Landmark, Cummins).

No results were found

Slug and snail activity and baiting

Snail and slug feeding and reproductive activity is in full swing. For snails, SARDI research supported by GRDC is showing that significant reproductive activity is likely to continue through to approximately July. Where warranted, we recommend continuing to bait snail-affected paddocks and/or paddock areas strategically to minimise reproduction until approximately July. Some juvenile snails may soon appear in paddocks, even after baiting treatments. Recent research has shown that baits can kill juvenile snails at comparable rates to adult snails, however their small size, reduced mobility, and the presence of stubble and crop plants on the surface, often reduce their rates of bait encounter, and survivors may still be numerous. Rainfall can degrade the physical integrity of baits; therefore, we recommend avoiding applying baits in advance of rain events (>10mm). See the SARDI slug and snail baiting guidelines.

Slug activity has significantly increased at a trial site at Finniss on the Fleurieu Peninsula since mid-May. Refuge traps have shown that the black-keeled slug, Milax gagates, grey field slug, Deroceras reticulatum, and the striped slug, Lehmannia nyctelia, have increased to an average of around 2-5 slugs per refuge (Figure 1). Since early June, slug eggs have also been found on the soil surface under refuges at Finniss, indicating reproduction, and also reported at Bool Lagoon in the South East. In a trial over the past few weeks, bait lines (bait pellets spread thickly along a single furrow) have been very effective as a monitoring tool for detecting slug activity as an alternative to refuge traps. Baiting for slugs should occur at sowing to protect crops as part of integrated control (see PestFacts Issue 2, 2018).

Plot: Slug activity at Finniss, South Australia
Plot: Slug activity at Finniss, South Australia
Slug eggs on the soil surface (Photo: K. Perry)
Slug eggs on the soil surface (Photo: K. Perry)

Source of Reports: Adam Hancock (Elders, Naracoorte), SARDI

Regional overview of pest observations

Over the past few weeks, we have received only isolated reports of pest activity. After checking in with regional agronomists, we can report the following recent observations:

In the SA Mallee, patchy and isolated pockets of Bryobia mite and low numbers of Mandalotus weevil have been observed in canola. In the Lower Southeast around Naracoorte, Lucerne flea has been observed in areas with heavier soil types and increasing in number following rainfall events, and earth mites are reportedly having a higher impact on crops this year than typical. On upper Yorke Peninsula around Kadina, Lucerne flea has been observed in some areas on crops not insecticide-treated earlier in the season. On Eyre Peninsula, redlegged earth mite has been observed moving into crops from paddock perimeters around Cummins, and possible sightings of brown wheat mite, Petrobia latens, has been reported in moisture-stressed cereals between Cowell and Kimba (identity to be confirmed). In addition, several samples of the pill bug, Armidillidium vulgare, have been submitted and identified in association with damage to canola at Mundoora, Mid North, in lentil crops at Winulta, Yorke Peninsula, and from around Bordertown, South East, as we requested in the previous issue (see PestFacts Issue 3, 2018).

We are interested in hearing any and all questions and observations of pest invertebrate activity in broad acre crops, even the ‘usual’ ones. Reports can be submitted online using the PestFacts Map, on twitter @PestFactsSARDI or by contacting us directly: Rebecca Hamdorf p: 08 8429 0682 e: rebecca.hamdorf@sa.gov.au or Kym Perry p: 08 8429 0738 m: 0421 788 357 e: kym.perry@sa.gov.au. Identification services are free to all subscribers, specimens can be posted in a non-crushable container, or images sent by SMS, Twitter or email.

Source of reports: Lou Flohr (Byrne Ag Landmark), Adam Hancock (Elders Naracoorte), Chris Davey (YP Ag, Kadina), Nigel Myers (Landmark Cummins).

Page Last Reviewed: 22 Jun 2018
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