Etiella in mungbeans and soybeans – do we manage the threat or the pest?

There is an under­stand­able level of con­cern about how best to man­age etiella (Etiella behrii) in sum­mer mung­bean crops fol­low­ing the unex­pect­edly high etiella infes­ta­tions (and cor­re­spond­ing seed dam­age and con­t­a­m­i­na­tion) in spring mung­bean crops on the Downs and in Cen­tral Queens­land and North West­ern New South Wales.

Respond­ing to the etiella threat with­out react­ing pre­ma­turely and cre­at­ing more pest prob­lems.
It is unclear whether the etiella pop­u­la­tion will remain high and pose a major threat to the sum­mer crop. Depart­ment of Agri­cul­ture, Fish­eries and Forestry (DAFF) ento­mol­o­gist Hugh Brier and Tech­ni­cal Offi­cer Adam Quade have recently (10 Feb­ru­ary) mon­i­tored soy­bean crops in the Branchview region, and mung­bean crops (rang­ing from veg­e­ta­tive to early pod fill) in the Bowenville and Jim­bour regions. This mon­i­tor­ing work included crops close to earlier-infested spring crops (now har­vested). No sig­nif­i­cant or obvi­ous etiella dam­age or moth activ­ity was observed in these crops and unlike in 2014, etiella activ­ity in Jan­u­ary sam­ples from the Branchview soy­beans was extremely low. One point that needs to be made is that crops in the veg­e­ta­tive and flowering/early pod­ding stages are at much lower risk of ‘sur­prise attack’ than crops at the late pod­fill stage. This is because the early signs of dam­age are man­i­fested by dead or dying axil­liary buds, whereas in pod­ding crops, the pest’s pres­ence is often not detected until lar­vae exit the pods just prior to pupation.

Etiella moth - 12 mm long

Etiella moth — 12 mm long

An early indi­ca­tion of etiella activ­ity in mung­beans prior to budding/flowering is the num­ber of moths vis­i­ble in the canopy. If num­bers are high, the moths will be eas­ily vis­i­ble fly­ing in the crop as you walk through. Etiella moths are small, slen­der and grey with very pro­nounced, for­ward pro­ject­ing mouth­parts. The moths come to rest with their wings folded back along the body. The forewing has a dis­tinc­tive white stripe along the lead­ing edge (see image). A sweep net can be used to col­lect moths from the canopy for identification.

The other indi­ca­tor of etiella activ­ity is dam­age to the plant’s axil­liary buds (the pre­cur­sor to the flo­ral buds). Dam­aged buds turn pale grey or straw in colour, and may be cov­ered with fine web­bing and frass.

Etiella damage to mungbean buds.  Look for dead buds, fine webbing and frass

Etiella dam­age to mung­bean buds. Look for dead buds, fine web­bing and frass

As the flo­ral bud­ding stage approaches, be on the look­out for sim­i­lar dam­age caused by bean pod­borer, the web­bing and frass of which will be coarser/larger. Bean pod­borer have already been observed in spring crops in Cen­tral Queens­land, and may con­tinue to be active if favourable (rainy) grow­ing con­di­tions are expe­ri­enced for the remain­der of the mung­bean grow­ing sea­son. Lar­vae of the two species, etiella and pod­borer, are quite dif­fer­ent, the for­mer being green/cream with pink stripes, and the lat­ter very pale cream with numer­ous black spots.

Etiella damaged mungbean pod with frass inside

Etiella dam­aged mung­bean pod with frass inside

 

 

Medium etiella larva (5 mm), with typical pale green colour and pink stripes.

Medium etiella larva (5 mm), with typ­i­cal pale green colour and pink stripes.

Options and con­sid­er­a­tions for min­imis­ing etiella damage.

In south­ern Aus­tralia where etiella is a major pest of lentils, it is man­aged by spray­ing syn­thetic pyrethroids to kill moths when they are active in the crop. The tim­ing of these treat­ments is guided by a model that pre­dicts the start of etiella activ­ity in spring. The syn­thetic pyrethroids pro­vide short-lived knock­down of moths in the crop.
In a mung­bean crop, the pro­phy­lac­tic use of syn­thetic pyrethroids increases the risk of flar­ing heli­cov­erpa and mites because ben­e­fi­cial insects are killed off. Be aware that syn­thetic pyrethroids pro­vide lim­ited con­trol of mirids because they have knock­down effect, but no resid­ual con­trol. The effi­cacy of syn­thetic pyrethroids on heli­cov­erpa will also be lim­ited by the level of resis­tance and size of lar­vae in the crop.
Where Alta­cor® is used for heli­cov­erpa and/or pod­borer con­trol in mung­beans, it might also be expected to give con­trol of etiella lar­vae as they hatch and enter buds, flow­ers or green pods. The effi­cacy of Alta­cor® against etiella is cur­rently being inves­ti­gated by Hugh Brier. Alta­cor® has proven to be very effec­tive against pod­borer feed­ing inside mung­bean buds and flow­ers, so it is rea­son­able to pre­dict it will also be effec­tive against etiella lar­vae feed­ing inside buds and flow­ers.
How­ever, once etiella are inside pods, DAFF tri­als and mon­i­tor­ing of etiella-infested spring crops sug­gest Alta­cor® (and most likely any other prod­uct) will have no impact on this pest. In con­trast, tri­als sug­gest heli­cov­erpa in pod­ding crops will be con­trolled. This is because small lar­vae can­not pen­e­trate pods and feed ini­tially on buds/flowers, while larger lar­vae tend to move in and out of pods and are thus exposed to more insec­ti­cide.
If Alta­cor® proves to be effec­tive in pre­vent­ing the estab­lish­ment of etiella lar­vae in flow­ers and pods, it will pro­vide a more tar­geted and less dis­rup­tive option than pro­phy­lac­ti­cally spray­ing crops to kill moths with syn­thetic pyrethroids.

Etiella damaged mungbean.

Etiella dam­aged mungbean.

Etiella seed dam­age, qual­ity issues and thresholds

In late-podding mung­beans, etiella can par­tially dam­age as many as 4–5 seeds per pod. Many of these seeds are car­ried through into loads of har­vested seeds deliv­ered to the pack­ing sheds. This results in grade outs and qual­ity down­grades. In late pod­ding soy­beans the sit­u­a­tion is sim­pler, as the major­ity of lar­vae eat only one seed, equat­ing to about 0.2g/larva grain loss. As seeds are nearly totally con­sumed, the seed rem­nants are lost at har­vest and the pest’s impact is mostly con­fined to yield loss. Thresh­old cal­cu­la­tions for soy­beans sug­gest the­o­ret­i­cal thresh­olds are very high at 35–40 lar­vae per square metre, assum­ing lar­vae can be killed. The catch is that they won’t be killed once they are inside pods, so any thresh­olds in pod­ding crops will have to be based on moth activ­ity – watch this space.

Posted in Etiella, mungbeans, soybeans | Leave a comment

Locusts and grasshoppers active across western regions and central Queensland

Spur-throated locust nymph (QDAFF)

Spur-throated locust nymph (QDAFF)

Locusts and grasshop­pers are active across large areas of west­ern Queens­land and NSW and cen­tral Queens­land. Reports of the Aus­tralian Plague Locust, Migra­tory Locusts,  Yel­low winged locust and spur-throated locust have been received from areas around St George to the Cen­tral High­lands dur­ing Jan­u­ary and early February.

It has been sev­eral years since we have seen such high locust and grasshop­per activ­ity, and although the Aus­tralian Plague Locust Com­mi­sion (in their sit­u­a­tion report and fore­cast­ing) is not pre­dict­ing a plague, their pre­dic­tions of locally high activ­ity seem to be accu­rate. In affected areas, there is the risk sig­nif­i­cant crop and pas­ture loss, with a num­ber of sorghum crops treated already to limit defoliation.

For infor­ma­tion on locust and grasshop­per iden­ti­fi­ca­tion, life­cy­cle and dis­tri­b­u­tion these are use­ful resources:

QDAFF Fact­sheet: pro­vides an overview of each species (with pictures)

Spur-throated locust  Fact­sheet (NSW DPI)

On-line locust and grasshop­per iden­ti­fi­ca­tion guide (Aus­tralian Plague Locust Com­mis­sion (APLC))

The Aus­tralian Plague Locust Com­mis­sion issues sit­u­a­tion reports and a Locust Bul­letin. The most recent Bul­letin was pro­duced in Jan­u­ary 2015. You can read the detailed descrip­tions of locust activ­ity and pre­dicted activ­ity in the APLC sit­u­a­tion report and fore­casts.

If con­trol is war­ranted to pre­vent crop loss, fipronil is an effec­tive option now avail­able for use in sorghum at extremely low rates (6.25 mL/ha (200 SC) and 1.5 g/ha (800 WG) applied directly onto hop­pers or winged adults. Apply­ing insec­ti­cide to pro­vide a bar­rier around crops is also an option. It is crit­i­cal that you read the label, par­tic­u­larly in rela­tion to water rates for appli­ca­tion, the impact of rain­fall and with­hold­ing peri­ods for harvest/grazing/slaughter.

Per­mits are also in place for locust and grasshop­per con­trol with a num­ber of syn­thetic pyrethroids (PER10927 and PER10928).

Report locust and grasshop­per activ­ity to Biose­cu­rity Queens­land on 132523 (rel­e­vant BQ staff are Michelle Janes in CQ; Craig Hunter for other areas).

To report locusts in NSW please con­tact Local Land Ser­vices www.lls.nsw.gov.au/contact-us

For more infor­ma­tion on locusts in NSW, visit www.dpi.nsw.gov.au/agriculture/pests-weeds/insects/locusts

 

Posted in Locusts, sorghum | Leave a comment

Soybean moth active in North Queensland

Sig­nif­i­cant soy­bean moth activ­ity has recently been reported in some Bur­dekin soy­bean crops. Soy­bean moth is a gen­er­ally a minor soy­bean pest but sig­nif­i­cant out­breaks have been reported peri­od­i­cally in all soy­bean grow­ing regions.

Feed­ing dam­age
Lar­vae feed mostly within the leaves, mak­ing dis­tinc­tive pale leaf mines, and often dis­tort­ing leaves.

Soybean moth larvae and typical leaf mining damage

Soy­bean moth lar­vae and typ­i­cal leaf min­ing damage

Soy­bean moth is present in low num­bers in most crops. How­ever, in some sea­sons a pop­u­la­tion explo­sion can lead to huge num­bers with over 1000’s of lar­vae per square meter. Such large pop­u­la­tions can totally defo­li­ate a crop.

 

 

Reg­u­lar crop sam­pling will pick up the early stages of dam­ag­ing pop­u­la­tions, specif­i­cally the numer­ous pale small feed­ing mines per leaflet. Stressed sec­tions of a crop are often more heav­ily infested.

Soybean moth damage

Soy­bean moth damage

Severe damage throughout the crop

Severe dam­age through­out the crop

Iden­ti­fi­ca­tion
Soy­bean moth lar­vae are small, reach­ing only 7 mm in length and are grey-green. Larva should not be con­fused with the much larger legume web-spinner (14 mm) which is a brighter green and webs leaves together, rather than min­ing within the leaf. Note that soy­bean moth lar­vae in the pre-pupal stage turn pale before pupat­ing in folded leaves.

Pre-pupal larvae and pupa. Top pupa is parasitised

Pre-pupal lar­vae and pupa. Top pupa is parasitised

The emerg­ing moths are small (6 mm long) with dark folded wings with a white band. The legume web-spinner moth is much larger (18 mm wingspan) and is brown with yel­low markings.

Soybean moth adult

Soy­bean moth adult

Thresh­olds
Thresh­olds are based on per­cent­age defo­li­a­tion. In veg­e­ta­tive crops, 33% leaf tis­sue death (min­ing) is allow­able before yields are com­pro­mised. How­ever, the tol­er­a­ble % falls to less than20% dur­ing pod-fill.

Con­trol
Soy­bean moth are eas­ily con­trolled with Abamectin at 300 mL/ha under per­mit 14288 (valid until 30 June 2017). Check that lar­vae are not in the pale pre-pupal stage as they will have stopped feed­ing and will not be con­trolled by the insec­ti­cide. Feed­ing lar­vae die inside the leaves and turn an opaque grey colour.

Arti­cle by Hugh Brier and Kate Charleston

Posted in grains, soybeans | Leave a comment

Lucerne crown borer on the move in soybean in 2015

Lucerne crown borer (Zygrita diva) (LCB) is caus­ing severe dam­age in a num­ber of soy­bean crops in the Bund­aberg region of SE Qld, and on the North Coast region of NSW. In some cases up to 75% of plants are infested and early plant death is evident.

Dam­age seems to be worse in the early (November-planted) crops which were sown in or adja­cent to pad­docks planted to soy­beans last year.

Lucerne crown borer in early planted soybean at Bundaberg. Image by Simon Andreolli

Lucerne crown borer in early planted soy­bean at Bund­aberg.
Image by Simon Andreolli

In some early crops, lar­vae are already pupat­ing, with stem girdling and plant death occur­ring in crops that are only at the pod set stage. In these crops, it is likely that, after pupa­tion, emerg­ing bee­tles will re-infest the crop. The sec­ond round of pupa­tion will most likely not occur until pods are fully filled, but this could be ear­lier if heat wave con­di­tions return.

Once only a spo­radic pest in some sea­sons, LCB num­bers seem to be increas­ing in coastal soy­bean grow­ing regions. How­ever, because of its biol­ogy and feed­ing behav­iour, con­trol is difficult.

Biol­ogy and Dam­age
LCB over­win­ter as pupae in soy­bean stem stub­ble. Bee­tles emerge in the spring/early sum­mer. They are not strong fliers, and hence soy­bean planted in pad­docks that had soy­bean the pre­vi­ous sea­son (or adja­cent to such pad­docks) are at greater risk.
The prox­im­ity to other LCB hosts such as lucerne and phasey bean is also a risk factor.

Adult crown bor­ers lay eggs in a slit in the stems of young plants. The hatch­ing lar­vae then tun­nel imme­di­ately into the stems where they feed on the stem pith, i.e. not the vas­cu­lar tis­sue. Lar­val feed­ing in the pith does not affect yield, but the dam­age is caused when lar­vae com­mence pupa­tion. Lar­vae gir­dle (inter­nally ring­bark) the lower stem to plug the pith tun­nel and pupate in the tap root.

Stem girdling at pupation

Stem girdling at pupation

LCB dam­aged pith turns a red brown to orange colour, but be aware that tun­nelling by other pests can cause a sim­i­lar discolouration.

Pupa­tion can be trig­gered as crops dry down or through heat stress, espe­cially in early planted crops. In crops where pupa­tion occurs when pods are not yet set or filled, yield losses can be severe. Yield losses are far lower if pupa­tion occurs when pods are nearly or fully filled, pro­vided that the dam­aged plants do not lodge before harvest.

Chem­i­cal con­trol
Crown borer lar­vae can­not be con­trolled with insec­ti­cides. Because they feed on the pith inside stems, they can­not be reached even by sys­temic insec­ti­cides or those with ‘upward xylem mobil­ity’ such as Altacor.

Lucerne crown borer adult, three barred type

Lucerne crown borer adult, three barred type

Although the adult crown borer may be sus­cep­ti­ble to a num­ber of insec­ti­cides, they invade crops over an extended period of time which would require mul­ti­ple sprays to give sat­is­fac­tory pro­tec­tion. Please note that NO insec­ti­cides are reg­is­tered against LCB lar­vae or adults.

Cul­tural control

On a long-term area-wide basis, cul­tural con­trol offers the best means of man­ag­ing this pest effec­tively and sus­tain­ably, with­out cre­at­ing other pest prob­lems. Spe­cific strate­gies include:

Crop rota­tion: Do not plant soy­beans in the same ground as last year. Where pos­si­ble, plant crops as far as pos­si­ble from last year’s plant­i­ngs. Avoid plant­i­ngs into or close to lucerne. Crop rota­tion is also a key strat­egy to reduce the build-up of inocu­lum of soil borne dis­eases such as char­coal rot and pho­mop­sis.
Weed con­trol: Elim­i­nate weed hosts such as phasey bean, ses­ba­nia and budda pea.
Time of plant­ing: Avoid early plant­ing as these crops have a greater risk of early dam­age.
Post-harvest cul­ti­va­tion: Aim to split stems and roots and bury stub­ble to a depth of at least 10 cm. Split­ting the tap roots destroys LCB’s over­win­ter­ing refuge, and bury­ing stub­ble reduces the emer­gence of bee­tles in the fol­low­ing spring. This is a key strat­egy to attack the pest at its most vul­ner­a­ble stage. Although cul­ti­va­tion opposes the zero till phi­los­o­phy, strate­gic cul­ti­va­tions may be needed to not only man­age this pest but also reduce the inocu­lum build-up of soil borne dis­eases such as char­coal rot and pho­mop­sis.
Min­i­mize lodg­ing: Higher sow­ing rates will lead to denser plant stands that can sup­port gir­dled plants and reduce lodg­ing.
Min­imise water stress: In irri­gated crops, do not allow crops to become stressed. Stress can trig­ger early plant girdling. In dry-land crops, poten­tial crop stress is a major rea­son to avoid those early plant­i­ngs in which plants grow much larger, and hence need more water.
Har­vester set up: Ensure har­vester set-up allows for pick­ing up any side branches that have drooped or plants that have lodged due to LCB damage.

Other stem tun­nelling pests
Other pests can also be found tun­nelling in soy­bean stems. In recent sum­mers, sig­nif­i­cant etiella out­breaks were reported in veg­e­ta­tive soy­beans in the Bur­nett and Dar­ling Downs in Qld, and in NW NSW. Major soy­bean stem fly out­breaks were reported the North­ern Rivers of NSW in 2013 and lesser num­bers in 2014. Stem fly were detected in rel­a­tively low num­bers in the South Bur­nett in 2014, and have recently been reported in the Bur­dekin. A sig­nif­i­cant stem fly out­break was reported near Mackay in 2009. Both etiella and stem fly cause sim­i­lar dis­coloura­tion of the pith, but their lar­vae are very dif­fer­ent. Etiella lar­vae are pale green/cream with pink stripes, while soy­bean stem fly lar­vae are small mag­gots with­out a dis­tinct head capsule.

Use the search func­tion on the Beat­sheet to find more infor­ma­tion about Etiella and Soy­bean stem fly.

Arti­cle by Hugh Brier and Kate Charleston

Posted in grains, pulses, soybeans | Leave a comment

Overview of the green peach aphid and beet western yellows virus outbreak in southern Australia (2014)

In the autumn and early win­ter of 2014, large areas of canola in South Aus­tralia, Vic­to­ria and south­ern NSW were heav­ily infested with green peach aphid (GPA), and many of the infested crops tested pos­i­tive for beet west­ern yel­lows virus (BWYV). GRDC TV  has com­piled a series of three videos that dis­cuss what fac­tors con­tributed to the GPA out­break, and key man­age­ment issues that have been highlighted.

Whilst GPA has not been a major pest in canola crops in the north­ern region, it is often present in low den­si­ties in veg­e­ta­tive — flow­er­ing crops. Con­se­quently the lessons that are being learned from the south­ern region out­break in 2014 may be crit­i­cal to the man­age­ment of GPA and BWYV in the north­ern region in sea­sons that favour GPA outbreaks.

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Grass blue butterfly damage to navy bean pods

Grass blue butterflies

Grass blue butterflies

The lar­vae of the grass blue but­ter­fly (Ziz­ina labradus) are nor­mally minor leaf feed­ing pests, although they can be dam­ag­ing in seedling crops where they attack ter­mi­nals and axil­lary buds.

Soy­beans are their favoured sum­mer pulse host, but they can also attack other pulses includ­ing navy beans. Read More »

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Etiella alert for mungbean on the Darling Downs, Goondiwindi and Northern NSW growing regions

A sig­nif­i­cant etiella out­break was recently reported in pod-filling mung­bean in the Moree region of North West­ern NSW. In this par­tic­u­lar crop, it is esti­mated that etiella lar­vae have infested pods on 50% of plants. Etiella eggs, at low den­si­ties, were also recently observed in an early flow­er­ing crop near Bun­gunya (west of Goondi­windi, Qld). Read More »

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Bruchids infesting pulse crops in the field

There have been two reports recently of cow­pea bruchid activ­ity, with these pests infest­ing pulse crops in the field prior to har­vest. The first report con­cerned the cow­pea bruchid (wee­vil) Cal­loso­bruchus mac­u­la­tus in field peas from Goondi­windi. The bruchids were noticed at intake and con­tin­ued to breed in an untreated grain sam­ple post-harvest. This clearly indi­cated they were not pea wee­vils (bruchids) Bruchus piso­rum, which do not breed in stored grain. Read More »

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Watch for Rutherglen bugs moving from canola into neighbouring crops.

Ruther­glen bug (RGB) num­bers in canola stub­ble are again high in some fields. These infes­ta­tions pose a risk to neigh­bour­ing crops, either through dam­age to estab­lish­ing sum­mer crops or con­t­a­m­i­na­tion of unhar­vested win­ter crops. Both the canola and adja­cent crops war­rant mon­i­tor­ing for RGB infes­ta­tion and move­ment out of the canola field. If large num­ber of nymphs move into adja­cent fields with seedling sum­mer crops (cot­ton, mung­bean, soy­bean, sorghum, maize) they can cause the seedlings to dehy­drate and die from sheer feed­ing pres­sure Read More »

Posted in canola, cotton, Rutherglen bug | Leave a comment

Seedling thrips in spring mungbean crops

There have been sev­eral reports of seedling thrips in spring mung­bean crops in the Goondi­windi region. Seedling thrips (Thrips tabaci) are also known as win­ter cereal thrips or cot­ton seedling thrips. The thrips move out of win­ter cere­als when these start to dry off into new green spring growth such as mung­bean, navy beans or cot­ton. Spring planted crops, espe­cially those in close prox­im­ity to matur­ing cereal crops are at great­est risk. In most cases, early thrips dam­age does not trans­late to yield loss. How­ever if you fear an extended thrips inva­sion and you do spray, please leave some unsprayed strips to deter­mine if the spray was worth­while. Read More »

Posted in Crops, mungbeans, pulses | Leave a comment
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