Australian plague locust control: industry and community information (excluding horticultural crops)

Apiculture

During spring and summer, insecticides can be used over large areas of the agricultural regions to control Australian plague locust (APL) infestations that could impact crops.

Horticulturists are likely to spray their crops even though many are netted. Locusts have been reported as ‘eating’ shade cloth and netting.

Honeybees are susceptible to insecticides. Beekeepers may need to avoid some honey flow areas if landholders are spraying for locusts.

Beekeepers contracting pollination services to growers in locust-affected areas will need to take into consideration the possibility of having to move their honeybees during the pollination period, due to the application of insecticides, which may affect the conditions of their pollination contract.

Management options

• Keep yourself informed on locust issues. Also, make sure the property owner has your contact details.
• Consider moving beehives to a honey flow in another location, and where nectar resources are available, to avoid the risk of pesticide sprays that kill honeybees.
• If more than one apiary is located in a susceptible area, arrange for another beekeeper to assist with moving the apiaries at short notice to an alternative safe area.
• Beekeepers involved in pollination services may need to consider changing the condition of their pollination contract to permit the movement of beehives, if their honeybees are threatened by the application of insecticides to control locusts during the pollination period.

Aquaculture

Landholders are responsible for control of locusts on their property. The Department of  Primary Industries and Regional Development (DPIRD) is committed to providing  relevant information to landholders to assist them with decisions on control.

Landholders will need to control hoppers and flying locusts that are causing damage on their own properties.

The main aim of landholder control operations is to kill locusts in the hopper stage.

Landholder locust spraying, yabbies and farm dams

• Follow label recommendations for buffer zones to avoid any impact on yabbies in farm dams.
  If spraying inside buffer zones then it is advisable to wait 14 days before attempting to restock the dam.

• After 14 days, restock the dam with a few yabbies in a cage that will act as biological indicators.

• The yabbies will need access to mud to ensure it replicates their free state within a typical dam.If these yabbies are still alive after seven days, it can be assumed that the dam is now ok to go back into yabbie production.

• If yabbie owners are concerned about residue levels from the spraying they could also get their dam water analysed at their cost (this can be expensive) by the ChemCentre or seek the advice of the chemical manufacturer on yabbie withholding times for particular chemicals.

Crops

During spring and summer, insecticides can be used by landholders to control locust infestations that could damage crops.

Crops such as wheat, barley and particularly oats are susceptible to damage from locusts. The susceptibility of lupins, canola, chickpeas, field peas and faba beans is uncertain, but all could potentially be attacked while they remain green.

Established green crops tend to be avoided by hoppers, although the edges of crops can be damaged. Crops that are beginning to dry off when locusts begin to fly are susceptible to damage; locusts cause little if any damage to crops that have dried off.

Even slight damage to grain crops could justify the costs of control.

As a general rule, hopper and adult numbers should be closely monitored, and if any damage is seen, then spraying should be commenced immediately.

The Grain Industry Association of Western Australia (GIWA) and Grain Trade Australia (GTA) have receival standards for field insects which include grasshoppers/locusts. The CBH Harvest Guide is available from the CHB website.

Comply with withholding periods for any insecticides sprayed on crops.

Management options

• Assess how much of the cropping program and individual crops are at risk.
• Canola after leaf drop – low risk
• Lupins pod bronzing – low risk
• Pulses pod yellowing – low risk
• Cereal completely dried off – low risk
• Conduct a cost/benefit analysis of locust control.
• Take into consideration the cost of running over the crop (crop damage) with a boomsprayer versus application by a mister or aircraft.
• Consider how long it will take to spray using a boomsprayer versus application by a mister or aircraft.
• Limit swath width of misters to 50m.
• Consider crop desiccation in mid-October in an effort to make crops unattractive to swarming adults.
• If you consider it necessary to spray for locusts refer to registered insecticides web page for chemical options and rates.

Home gardens

During spring and summer large numbers of locusts can be present over a large area of the agricultural regions of Western Australia.

Initially locusts can be distributed in paddocks on farms but hoppers and adult locusts are very mobile and will move to homesteads and rural towns. Because of the concentration of irrigated plants in gardens relative to surrounding areas, locusts can quickly build up to high numbers in gardens causing damage. Locust hoppers and adult locusts may enter gardens over a number of weeks.

The following products are registered for control of grasshoppers and are readily available from your local nursery or hardware store and rural merchandise suppliers. Remember to always read and follow chemical label directions, and wear safety gear. Refer to the  Australian Pesticides and Veterinary Medicines Authority (APVMA) for further details.

Locust control in home gardens

• The damage that large numbers of locusts can do to gardens can only be stopped by the use of insecticides.
• Because gardens can be damaged quickly, landowners need to act immediately if a swarm of locusts arrives.
• Nurseries and hardware retailers can supply the small quantities of insecticides needed for individual home gardens and advise on their safe use.
• It is important that label directions relating to rates of application of insecticides in gardens are followed.
• In addition, other animals like sheep and poultry can also be affected and therefore early liaison with neighbours is essential.

Livestock and poultry

Landholders are responsible for control of locusts on their property. DPIRD is committed to providing timely and relevant information to landholders to assist them with decisions on control.

Poultry spraying issues

• Do not expose poultry to locust sprays. To minimise risk of residue intake poultry should be locked up for 14 days after spraying to prevent access to dead locusts.
• If poultry owners are concerned about residue levels from the spraying, they can get their eggs analysed at their cost (this can be expensive) at the ChemCentre or seek the advice of the chemical manufacturer on the poultry and egg withholding times for particular chemicals.

Over-spraying sheep and other livestock

• Avoid over-spraying livestock where possible.
• If livestock are over-sprayed follow the appropriate grazing witholding periods (WHPs) and export slaughter inervals (ESIs). Refer to refer to registered insecticides web page for chemical options and rates and Safemeat Australia. If sheep are over-sprayed they should be held for 14 days before shearing.

Organic farming

Landholders are responsible for control of locusts on their property. DPIRD is committed to providing timely and relevant information to landholders to assist them with decisions on control.

Landholders are responsible for the control of locust infestations that are causing damage on their own properties.

Organic farming management options

• Where landholders are conducting their own spraying, organic farmers should liaise with neighbours and discuss sensitive areas and buffer zones and how they affect intended spraying programs, well before spraying commences.
• A naturally occurring fungus, Metarhizium anisopliae, known commercially as Green Guard®,  is appropriate for use on organic farms. The fungus should be applied when the locust hoppers are in the early stages so there is time for it to kill a large proportion of the locusts. Unlike other pesticides it takes several days to have an effect and it will not protect plants if significant damage is already occurring or is imminent.

Pastures

During spring and summer, insecticides can be used by landholders to control locust infestations that could damage pasture.

Hopper and adult locusts can cause considerable damage to pastures. It is estimated that 20 hoppers per square metre eat the equivalent of three to five sheep per hectare each day. Damage to pastures by locusts will affect both the quantity and quality of pasture. Locusts will consume green pastures and pastures that have begun drying off.

Hoppers develop over six to eight weeks, depending on temperature. If green or drying pasture is available over this period, hoppers may complete their development at one locality and consume most of the pasture. Adult locusts may fly into a paddock and although their stay may be short, they can still consume a considerable amount of pasture. It may not be possible to effectively protect pasture in these situations.

Perennial pastures such as lucerne, long-season annual pastures and newly-sown pastures are at greater risk from locust damage later in the season, as they tend to remain greener for longer periods.

Locust attack has the potential to destroy one to two year old tagasaste and to strip older trees.

Growers need to identify high value pasture paddocks for special emphasis on control measures. These include newly sown pastures, pastures set aside for specialist seed production and lucerne. Any degradation to pastures caused by locusts may subsequently result in erosion in prone paddocks. Consideration needs to be given to the increased erosion risk on sandy soils if vegetative cover is removed. This may subsequently limit opportunities for grazing.

Treatment of locust swarms will need to be within hours of them arriving, which means frequent monitoring from mid-October onwards, if large infestations are in your area.

Withholding periods for livestock grazing and slaughter should be observed at all times.

Management options

• Hopper control in pastures is economic if hopper densities exceed 20 per square metre, if pasture is valued at the cost of replacement feed for livestock.
• Adult locust control in pastures is economic if locust densities exceed 10 per square metre.
• Other factors to consider in the decision to spray locust hoppers in pasture include:
• Pasture availability – whether there is a surplus or deficit of pasture on the farm.
• Stage of pasture growth – green pastures and pastures that are drying off are very susceptible to hopper attack, but pastures that have completely dried off are not favoured.
• When the pasture has completely dried off, other green plant material in the paddock or nearby may be damaged, for example, tree seedlings.
• If you consider it necessary to spray for locusts refer to DPIRD's registered insecticides web page for chemical options and DPIRD's spraying guide for withholding periods.
• Abide by the withholding period in sprayed paddocks.
• Where possible, the over-spraying of stock should be avoided. Otherwise, withholding periods apply.
• Consider spray-topping or hay-freezing additional low-value pasture paddocks. You will need to consider the relative costs of these pasture management treatments versus spraying locusts – which is the cheapest?
• Consider grazing or spraying established lucerne or other perennial pastures prior to locust attack.

Strategies to consider include:

• Reducing carrying capacity by selling livestock and/or agistment.
• Fodder conservation by making silage, hay and sacrificing crops.
• Supplementary feeding in conjunction with estimates of feed reserves, feed budgeting, retaining grain and lot feeding.

Trees

During spring and summer, insecticides can be used by landholders to control locust infestations that could impact crops.

Locusts eat green plant material – their preferred foods are green grass and green cereals. The immature hoppers will initially emerge from and develop in pasture paddocks. When the pastures are either eaten out or dry-off, any other green plant material is susceptible.

Most tree species are susceptible to attack from locusts, including native (eucalypts, she-oaks and wattles) and introduced (pines, olives, pistachio, etc.) species. Some species appear to be more susceptible to damage and death from attack than others - for example Allocasuarina huegeliana and some provenances of Eucalyptus camaldulensis.

Damage to trees during a locust outbreak may result from immature locusts (hoppers) which have developed on site or nearby (hoppers cannot fly but can travel hundreds of metres) or from adult locusts which fly into a site.

Locusts are less likely to do significant damage in plantations with closed canopies. Damage to trees can be unpredictable from both immature hoppers and adult locusts that fly in.

Trees remain green over the entire period the locusts are active and could be susceptible to attack over an extended period from November through to the next autumn (if summer rainfall allows the locusts to produce another generation over summer).

Where insecticide treatment is considered necessary, it is likely that treatment will not be 100% effective and that repeated treatments may be required. This is especially the case with trees given they are susceptible over a long period.

In recent years, large numbers of landcare, nature conservation and commercial tree species have been planted. All of these trees are also at risk of damage by locusts. Younger trees (less than three years old) are at greatest risk of attack and are more likely to be killed than mature trees. Trees planted individually or in narrow bands are at increased risk of damage from immature hoppers.

Plantation trees are at reduced risk of attack from immature locust hoppers once the trees have developed a closed canopy.

Most damage to trees will be from adult locusts. Greatest risk of damage will be in areas where the highest numbers of locust eggs were known to occur over winter.

Any setback of growth could have an adverse economic impact on commercial tree plantings.

Seed collection may be affected.

Management options

The following actions and management of trees should be considered:

• Monitoring for locusts should be undertaken by landholders from early September onwards.
• In areas of high risk of locust attack, consideration should be given to postponing any new tree plantings.
• Locust hatchings are not likely to be in revegetation areas more than one-year-old, and therefore most control will not be on revegetation areas. Treating areas of high locust concentration in adjoining pasture paddocks before they attack trees is likely to be more effective.
• Consideration should be given to grazing tagasaste to capture the grazing value prior to locust damage.
• Consideration should be given to netting high-value trees such as pistachio where it is economically viable. However, there have been reports of locusts ‘eating’ shade cloth and netting.
• Where there is a market, oil mallee trees could be harvested prior to a predicted attack.
• Where damage to trees is likely to result from nymphs originating near the trees, spraying with approved insecticides may be effective. Refer to DPIRD's registered insecticides web page for chemical options and rates.
• Where locusts fly into an area, damage can be very swift and severe and it may not be possible to effectively protect the trees. Any decision to treat in these circumstances must be made on commercial grounds. Treatment of locusts will need to be within hours of them arriving, which means frequent monitoring is a necessity, from November onwards.
• Tree plantings may be protected from locusts in the hopper stage invading from adjoining pasture areas by treating a band of pasture around the edge of the planting. Several treatments may be required.

Viticulture

During spring and summer large numbers of locusts can occur in the agricultural regions of Western Australia, and generally start flying in late September. Due to the high value of vineyards, landowners should act immediately if a swarm of locusts arrive.

Landholders are responsible for the control of locust infestations that are causing damage on their own properties.

Over a period of two to three weeks, locusts can fly up to 200km. Damage to vineyards is erratic in that locusts will fly over some vineyards and then land and feed on others. Although grapevines do not appear to be a favoured host plant, extensive damage may occur, particularly on boundary rows, when large numbers of insects are present. Damage to vineyards can be extensive with adult locusts stripping vines of leaves in hours.

Newly planted vines are more likely to be killed than mature vines. They have little carbohydrate reserves in their stem and root systems. If a significant proportion of the leaves are eaten, particularly if the locust attack occurs in early spring, the young vines are likely to die.

If the leaves of mature vines are eaten the vine will usually recover. If damage occurs early in the season, yields will be decreased and fruit quality may suffer. These vines should however produce normally the following year.

Where insecticide treatment is considered necessary, it is likely that treatment will not be 100% effective and that repeat treatments may be required.

Management options

• Where locusts fly into an area, damage can be very swift and severe and it may not be possible to effectively protect the vines. Any decision to treat in these circumstances must be made on commercial grounds. Treatment of locusts will need to be within hours of them arriving, which means frequent monitoring from early September onwards.
• Control in vineyards should be initiated as soon as any hopper damage becomes evident. The cost of control is almost certain to be less than the cost of even minor locust damage.
• In areas containing high locust egg numbers, consideration should be given to postponing any new vine plantings until the following year.
• Locust hatchings are not likely to be in vineyards more than one year old. Treating areas of high locust concentration in adjoining pasture paddocks before they attack vines is likely to be more effective. Where immature hoppers are invading vineyards from adjacent pastures, an insecticide barrier should be applied across the line of advance.
• Where damage to vines is likely to result from nymphs originating near the vineyard, spraying with insecticides registered for locust control in vines should be effective (refer to Grape vines in Australian plague locust control: horticultural crops).
• Do not spray chemicals which have no registration to control locusts on vines; observe withholding periods and read the label carefully. Grape growers should seek advice from their chosen winemaker regarding the suitability of insecticides to use on their vines.
• Grape growers and winemakers who are exporting wine should refer their enquiries to the Australian Wine Research Institute.