Sorghum midge economic thresholds

Cost and benefit of treating sorghum midge

The newly developed Economic Threshold Calculator allows growers to calculate the costs and benefits of spraying sorghum to treat sorghum midge outbreaks.

Sorghum midge is a widespread insect pest that breeds in sorghum, and costs from residual losses and uncontrolled damage have been estimated at $10 million annually in Australia.

Resistance traits introduced in all commercial sorghum hybrids in the 1980s have reduced the impact of midge. However, growers in the northern region still incur significant expenses on insecticides to reduce potential midge damage.

Growers can evaluate the costs and benefits of applying an insecticide with an online tool, the Economic Threshold Calculator, developed by researchers at the Department of Agriculture, Fisheries and Forestry, Queensland (DAFF).

This fact sheet describes how growers can use the calculator to manage insecticide applications, saving them time and money.

Key Points

• Sorghum midge is a 1–2 millimetre red fly that lays eggs in flowering sorghum spikelets. ––
• The midge larvae feed on the developing sorghum grains, ravaging the crop. ––
• Adult midge use plants other than sorghum to breed, such as the ubiquitous weed Johnson grass, so midge populations can build up before sorghum starts flowering. ––
• A high midge resistance (MR) rating does not guarantee a crop is immune from midge damage, especially when midge populations are high. ––
• The online Economic Threshold Calculator assesses whether growers will benefit from applying an insecticide. It considers the hybrid’s level of midge resistance, growing conditions, insecticide costs and commodity prices. ––
• A grower’s decision to treat depends on many factors, and the calculator helps growers determine the best strategy for their enterprise.

The Sorghum Midge Economic Threshold Calculator

The calculator helps growers decide whether to apply an insecticide by asking the question:

Is the number of midge high enough to justify insecticide and application expenses, or is the number too low to affect the crop yield?

The tool uses your specific farming conditions to provide tailored advice.

It is available online, along with information on how to collect the pest data used by the calculator, at thebeatsheet.com.au/sampling-2/.

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Region North

• 3.38 mbSorghum Midge Spray Calculator Fact Sheet: Cost and benefit of treating sorghum midge (high resolution)The newly developed Economic Threshold Calculator allows growers to calculate the costs and benefits of spraying sorghum to treat sorghumn midge outbreaks.  This fact sheet describes how growers can use the calculator to manage insecticide applications, saving them time and money.
• 335.50 kbSorghum Midge Spray Calculator Fact Sheet: Cost and benefit of treating sorghum midge (low resolution)The newly developed Economic Threshold Calculator allows growers to calculate the costs and benefits of spraying sorghum to treat sorghumn midge outbreaks. This fact sheet describes how growers can use the calculator to manage insecticide applications, saving them time and money.