Using the Forecast Explorer Tool to prepare for locust activity
The Forecast Explorer service for Victoria provides simple, interactive weather maps that will allow farmers and land managers to access temperature and wind forecasts, at a local level, up to seven days ahead.
You can point and click anywhere on the map, and zoom down to a 6km square to retrieve a seven day forecast of:
- Maximum and minimum temperatures
- Forecast rainfall totals
- Wind speed and direction
- Weather phenomena including frost, fog and thunderstorms
- Humidity
As well as providing forecasts for specific locations, the maps make it easier to understand how the weather is changing across your region over the coming week.
The Forecast Explorer tool and an accompanying online tutorial can be found on the Bureau’s website at www.bom.gov.au or in the Agricultural Services area www.bom.gov.au/watl.
Monitoring temperature and moisture conditions for hatching
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| Locust Swarm |
The Forecast Explorer maximum temperature maps provide useful information for predicting locust hatching times for farms with egg infestations. By monitoring the temperature and Australian Plague Locust Commissions (PLC) forecast hatching dates (available on the DPI website) land managers should be able to deduce when hatchings will begin in their area.
Note: the dates provided are for expected peak hatchings and hatching will occur over a period of several weeks around these peak dates.
Egg development is influenced by warm temperatures and moist conditions. Locust egg beds across much of northwest Victoria will begin to hatch as the weather conditions get warmer.
Navigating Forecast Explorer to find temperature information.
- Select maximum temperature map for the State or zoom to a specific district.
- By stepping through the maximum temperature maps for seven days ahead, threshold temperatures likely to trigger hatchings can be anticipated.
- Double click the mouse pointer over your farm to bring up maximum and minimum temperatures and expected rainfall for the next seven days for a 6km square at your place.
- Monitor these temperatures regularly to give an indication of when locust eggs are likely to hatch in your area.
- Once locust hatching dates approach it will be necessary to confirm with on the ground checks.
- Once hatchings have been confirmed planning can commence for a spraying campaign.
Monitoring wind conditions to assist in the planning of a spraying campaign
The best time to spray locusts is in the late second and third instar stage, when they form bands and before they are able to fly. Spraying with insecticides at this stage is very effective and can greatly reduce numbers, with the period of about two weeks after hatching the most effective and cost efficient. The diagram below shows where this stage occurs within the complete locust life cycle.
At this second and third instar stage the locusts, known as hoppers, are wingless and form large, slow moving bands, providing a clear target for efficient chemical use. The most effective treatment is achieved when hopper band densities reach or exceed 80 hoppers per square metre.
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| Locust life cycle diagram |
The immature hopper stages will last for around six to eight weeks in total, depending on temperature, but the late second to fourth instar stages last for about two to three weeks, making it important to carry out regular monitoring.
The best time of the day to spray hoppers is late morning through to late afternoon when they are most active and most visible. Weather conditions need to be favourable to ensure that spraying is effective and safe. Unless there are specific label directions, the following are some guidelines for determining optimal spraying conditions:
- A steady light wind of 3-15 km/hr, blowing away from sensitive areas
- A Delta T (ΔT, which relates temperature and relative humidity) of between two and eight
- Temperatures below 28ºC
- Calm conditions are to be avoided i.e. no inversion layer present
Additional resources:
- Further advice on how to minimise the risk of spray drift can be found on the DPI Chemical Standards website at www.dpi.vic.gov.au/chemicalstandards
- For information on understanding how to determine the best weather conditions for pesticide spraying see: http://www.bom.gov.au/info/leaflets/Pesticide-Spraying.pdf
Inversions can significantly reduce the amount of spray reaching its target and increase the chances of spray drift moving off site.
Navigating Forecast Explorer to find ideal conditions for spraying.
You can view a weekly forecast of wind speed and direction to help you plan for ideal spraying conditions.
- Select wind map for state or zoom to district.
- By stepping through the wind maps at three hourly or six hourly intervals for the next seven days the optimal day and time of day for spraying can be determined.
- Double click the mouse pointer over your farm to bring up maximum and minimum temperatures and expected rainfall for the next seven days at your place location to check that rain and temperature conditions are optimal for the spraying time chosen.
- Monitor forecasts daily to confirm the predicted conditions are holding and make adjustments to spraying program as required.
- Wind speed displayed on wind maps up to 20km/hr is denoted by white areas across the region.
- Over the coming weeks, as part of the preparation for spraying, it would be advisable to monitor wind speed and direction as presented on Forecast Explorer to understand how the conditions at your specific location relates to the forecast. Local features such as topography can cause a local variation to the prevailing wind flow as forecast.
- On the day when spraying is planned, measurements of actual conditions should guide decision making. Temperature, humidity and wind speed and direction should be taken to confirm conditions remain suitable to spray. Alternatively, if instruments are unavailable on site, the nearest Bureau Automatic Weather Station data can be obtained from: www.bom.gov.au/vic/vic-observations-map.shtml
These tools are recommended as guidance only. Please confirm local weather conditions on the day you plan to spray.
What are my obligations?
Land managers in Victoria need to be vigilant in monitoring their pastures, fodder crops and known locust egg beds for evidence of activity and crop damage.
The Australian Plague Locust has been declared an exotic pest under the Plant Health and Plant Products Act 1995, and this declaration places two important obligations on all land managers.
All land managers must notify DPI of the presence of locust activity on their land. Notifications can be made by calling the DPI Locust Hotline on 1300 135 559.
All land managers must treat locust hoppers on their land when numbers reach or exceed 80 locust hoppers per square metre. This must be completed before locusts grow wings and are able to fly.
Failure to notify or treat locusts is a breach under the legislation.
All chemical use must be in accordance with State laws and regulations, including record keeping requirements. For information, visit the DPI Chemical Standards website at www.dpi.vic.gov.au/chemicalstandards
Disclaimer
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
Developed in conjunction with the Bureau of Meteorology Victoria.
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Information on the locust situation and locust biology and management can be found at www.dpi.vic.gov.au/locusts Report locust hatchings or contact the DPI Locust Hotline on 1300 13 5559 |
