Spring control of redlegged earth mites in pastures using Timerite®
- Boyup Brook
Ben Creek (AGRIvise) has reported finding redlegged earth mites (RLEM) in pastures, particularly pasture with lots of capeweed, from Boyup Brook to Manjimup. Ben is concerned that forecasted frost events for this area may cause RLEM problems.
Spring has sprung and growers and consultants are reminded to monitor for RLEM in pastures and to find out their specific Timerite® spring spray date if spraying is necessary. Examples of Timerite® dates; Northam 11th September, Dandaragan 16th September, Tambellup 20th September, and Mount Barker 5th October.
The timing of the sprays is based on a short window of the season when RLEM have stopped laying winter eggs (eggs that must hatch this season) and before they start laying diapause eggs (over-summering eggs able to survive until next autumn).
Controlling mites at this time means that the whole population can be reduced, leaving few mites to carry-over to the following autumn.
Growers who have not already obtained their spray date that is specific to their locality can do so (free of charge) from the Australian Wool Innovation (AWI) Limited Helpline on 1800 070 099 or you can type the latitude and longitude of your property into the AWI TIMERITE® page to obtain your spray date and other useful information.
Studies by CSIRO have shown that spraying up to two weeks earlier or on the optimum spray date provides effective control of RLEM, however if spraying is delayed by two weeks after the optimum date the carry-over RLEM population into next autumn is much higher.
Farmers intending to spray paddocks should make the most of suitable weather conditions to go early or on time, rather than later than the predicted Timerite® date.
Growers are advised to spray only if they need to and to rotate chemical groups to stop resistance developing in RLEM. Repeated use of synthetic pyrethroid insecticides or organophosphates insecticides such as omethoate and chlorpyrifos provides strong selection pressure for RLEM to develop resistance. For more information refer to GRDC’s RLEM Resistance Management Strategy, and the IPM Guidelines for Grains website.
Growers who find RLEM that survive registered rates of insecticide treatments are encouraged to arrange for resistance testing to be conducted by contacting DPIRD entomologist Svetlana Micic, Albany on +61 (0)8 9892 8591 or 0427 772 051. The free-of-charge service, made possible with investment by the Grains Research and Development Corporation (GRDC), is led by The University of Melbourne, in collaboration with DPIRD, cesar, and CSIRO.
Grazing reduces mite carryover in pastures
The level of grazing and quantity of pasture feed on offer (FOO) is directly related to the numbers of RLEM. Department grazing trials have shown that pasture grazed to 1.4t/ha FOO during spring will have low levels of mites, equivalent to numbers after spraying pastures with high FOO level.
Spraying of pastures in spring will have little or no benefit where pasture FOO levels are kept low by grazing. Insecticides applied to control RLEM in spring pastures or legume break crops with FOO levels greater than 3t/ha will reduce their numbers and provide benefits by allowing increased spring growth and seed set and a much reduced potential for RLEM carry-over into next autumn.
However, increased production benefits can largely be wasted unless the increased feed is utilised by strategic grazing management or fodder conservation. It is recommended that farmers should not spray all pasture paddocks but rather select paddocks for spring spraying based on FOO levels, future grazing feed management, level of required seed production and intended paddock use next autumn.
For more information on RLEM refer to the department’s Diagnosing redlegged earth mite page.
For more information contact Dustin Severtson, Development Officer, Northam on +61 (0)8 9690 2160 or Svetlana Micic, Research Officer, Albany on +61 (0)8 9892 8591 or Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758.
Article author(s): Cindy Webster (DPIRD Narrogin), Dusty Severtson (DPIRD Northam) and Alan Lord (DPIRD South Perth).
Pea weevils emerge in spring so growers need to check field pea crops
Pea weevils emerge from their winter hibernation (often under the bark of nearby trees) usually at a time that coincides with early flowering and podding of field peas. They are also dependant on warming cumulative temperatures. In some seasons the pea weevil beetles emerge en masse to enter crops with a spell of warm weather such as several days above 25°C. In other years with mild and cooler temperatures the pea weevil emergence is delayed or staggered over a longer time frame.
Growers are encouraged to use a sweep net to check their field pea crops regularly to determine the presence and duration of pea weevil activity.
Finding pea weevil
Districts where field peas were grown last season and where patches of the crop were left un-harvested, or on-farm stored seed was not fumigated, are likely to have the largest populations of pea weevils.
Peas grown within a 5km radius of last year’s field pea crops will be most at risk of pea weevil attack.
Commencing sweep net monitoring before the first pods begin to form is recommended. Sweep netting should be done on sunny days during the warmest part of the day (temperatures >18°C). Pea weevils are most likely to be found first along the edges of paddocks nearest to trees and/or last year’s field pea stubble. Sample for pea weevil along the crop edges within about the first two metres.
If more than one pea weevil in 100 sweeps is present then spray a synthetic pyrethroid (alpha-cypermethrin, cypermethrin, beta-cyfluthrin, beta-cypermethrin, deltamethrin, esfenvalerate, gama-cyhalothrin, lambda-cyhalothrin etc.). In large paddocks clear of trees, it is usually only necessary to spray a 60m border around the paddock because pea weevils mostly remain near the crop edges of the paddock.
Eggs on pods and larvae in pods will not be killed by insecticide so it is important to kill adults before they lay eggs.
Recommence monitoring the crop about 10-14 days after spraying and if you find more pea weevils a further spray should be applied. In some crops a whole crop spray will be needed especially if any native budworm caterpillars are also found.
For more information contact Dustin Severtson, Development Officer, Northam on +61 (0)8 9690 2160.
Article author: Dustin Severtson (DPIRD Northam).
Native budworm activity update
- Wongan Hills
- Bruce Rock
- Grass Patch
Clare Johnston (Elders) has found an average of two caterpillars (0-5mm) per 10 sweeps in a canola crop west of Dalwallinu.
An agronomist has reported finding budworm caterpillars damaging a wheat crop east of Wongan Hills.
Matt Flint (DKT Rural Agencies) reports finding six budworm caterpillars per 10 sweeps in late flowering lupin crop near Kumbarning.
Brad Joyce (ConsultAg) reports finding an average of up to one budworm in ten sweeps at Quairading, Kellerberrin and Merredin. He found 10-11 budworm per 10 sweeps in a lupin crop north of Merredin. Brad noted that he was finding much fewer budworm in canola relative to pulses.
David Stead (Anasazi Agronomy) reports he has started to pick up budworm caterpillars in the sweep net in pulse crops in the Quairading, Bruce Rock and Corrigin areas. David has also found budworm caterpillars (3 to 6 per 10 sweeps and ranging from 7 to 10mm in size) in very early podding canola west of Cadoux and 1 to 2 caterpillars per 10 sweeps in very early podding lupins.
Development officer King yin Lui (DPIRD) reports finding native budworm caterpillars in a early flowering faba bean crop near Grass Patch.
Native budworm moth trapping surveillance
- Usual automated and manual trapping locations
The larger native budworm flights recorded by budworm trappers this week include; Wyalkatchem (225 moths), Kirwan (157), Badgingarra (64), Dowerin (63), Binnu (54), Southern Cross (54), Dalwallinu (50) and Kellerberrin N (49).
Results of this week's automated and manual trappings are available at the department’s Native budworm moth numbers 2019.
A mapped view of the native budworm trap captures is available at cesar’s MothTrapVisWA page. Viewers need to select the desired trapping date range.
The trap numbers only provide an indication of the pests activity and cannot be relied upon for control decisions. Only the use of a sweep net to regularly check crops can give growers confidence in the levels of budworm present.
Detailed information on this pest can be found at the department’s Management and economic thresholds for native budworm.
Pesticide options for the control of native budworm can be found in the department’s Winter/Spring Insecticide Spray Chart 2019.
Previous budworm activity and management information is available at DPIRD’s;
- 2019 PestFax Issue 15 article Native budworm and lesser budworm caterpillars are causing damage to crops
- 2019 PestFax Issue 14 article Native budworm moth numbers are high
- 2019 PestFax Issue 12 article Native budworm moth trapping and caterpillar activity .
For more information contact Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758 or +61 (0)409 689 468.
Article author: Alan Lord (DPIRD South Perth).
Powdery mildew in wheat
James Bee (Elders) has reported finding powdery mildew in a Zen wheat crop near Gnowellen. The crop is at ear emergence and Opus® fungicide was going to be applied. This was James first observed wheat powdery mildew in the South Stirlings / Gnowellen area. Rancona® Dimension has been used for crown rot and loose smut control.
When diagnosing powdery mildew in barley and wheat look for fluffy, white powdery growths of fungal spores on the either surface of leaves and leaf sheaths. Infection usually starts low in the canopy. Fluffy, white powdery growth also appears on stems and heads under severe disease pressure. As the infection ages there is a yellowing of the infected tissue and the infected area turns a dull grey colour with small black specks present.
Temperatures of 15-22°C favour the disease in conjunction with high humidity. Under favourable conditions the infection cycle can take as little as seven days.
It is crucial to control the disease before it becomes too severe and develops in the upper canopy and on heads as then it is very difficult to control. A registered foliar fungicide can reduce the disease impact, but growers need to consider the weather outlook, variety susceptibility, growth stage and crop yield potential when deciding whether an economic response to fungicide application is likely.
Zen is rated as being susceptible (S) to powdery mildew. For more wheat disease ratings refer to DPIRD’s 2019 Wheat variety sowing guide for Western Australia.
If wheat powdery mildew is present and increasing in the canopy and the weather outlook is favorable (humid and mild), it is recommended that growers intervene with a well-timed application of registered foliar fungicide in susceptible varieties to stop disease reaching damaging levels and moving onto the flag leaf and head.
For fungicide information refer to the department’s Registered foliar fungicides for cereals in Western Australia page.
Testing for powdery mildew fungicide resistance
Wheat powdery mildew is at high risk of developing fungicide resistance which is most likely to be against the older generation triazole (DMI or Group 3) fungicides such as tebuconazole.
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.
For more information on powdery mildew refer to the department’s;
- Diagnosing powdery mildew in cereals page
- Managing powdery mildew in wheat page
- Protecting WA Crops Issue 13 Environmental, crop nutrition and pathogen virulence factors influencing wheat powdery mildew in Western Australia
For more information contact Kithsiri Jayasena, Plant Pathologist, Albany on +61 (0)8 9892 8477, Geoff Thomas, Plant Pathologist, South Perth on +61 (0)8 9368 3262, Andrea Hills, Plant Pathologist, Esperance on +61 (0)8 9083 1144 or Ciara Beard, Plant Pathologist, Geraldton on +61 (0)8 9956 8504.
Article author: Cindy Webster (DPIRD Narrogin).
Article input: Kithsiri Jayasena (DPIRD Albany).
Upper canopy infection of blackleg in canola
- Wongan Hills
Crop production agronomy officer Stacey Hansch (DPIRD) has reported finding blackleg infection on pods of Stingray canola plants in an irrigated trial near Wongan Hills. There was no sign of infection in stems on leaves, just pods. The crop was sown on 20 March and was at the pod ripening stage.
With plants past the seedling stage, basal blackleg control options have expired. Leaf infections are common on varieties with no effective resistance, such as ATR Stingray and ATR Bonito.
Excluding leaves, upper canopy blackleg infections (UCI) will occur on varieties that are not rated as moderately resistant to resistant (MR-R) as bare seed, which includes ATR Bonito. UCI can infect all parts of the canola plant including flowers, whole heads (causing head abortion), stems, branches and pods. Note that another disease, alternaria, can also occur on pods and it is easily confused with blackleg. UCI is usually worse in very early sown crops.
In some situations upper canopy infections can cause yield loss but it is seasonally dependent and not easy to predict as trial work has shown that the visible symptoms and losses are not well related. While no fungicides are registered for UCI, growers concerned about these infections can use a fungicide registered for sclerotinia, up to full bloom stage.
More information on managing blackleg and past blackleg reports received this season is available at DPIRD’s;
- 2019 PestFax Issue 13 article Blackleg and sclerotinia stem rot are being found in canola
- 2019 PestFax Issue 8 article Canola diseases
- Managing blackleg in canola page.
Article authors: Andrea Hills (DPIRD Esperance) and Cindy Webster (DPIRD Narrogin).