Keeping sorghum safe

Weed competition during the establishment phase of sorghum can result in poor establishment, uneven maturity and harvest delays. Where weeds compete with the crop for nutrients and moisture, a yield penalty often occurs.

Key points

• Weeds need to be managed well to achieve high yields.
• A lack of post-emergent herbicide options for grass control in sorghum means that pre-emergent control is often required. Metolachlor-based herbicides are frequently used.
• To reduce the potential damage to seedlings that come into contact with this herbicide, a seed safener (Concep® II) is required.
• Sandy/coarse/low organic matter soils are at a higher risk of herbicide damage.
• Many factors affect the level of exposure to and metabolism of metolachlor within the germinating seedling.
• Following mixing and application guidelines to get the most out of Concep® II

Key points influencing sorghum safety when using metolachlor-based herbicides

Factors increasing the chance of sorghum injury

• Rainfall or irrigation between planting and emergence wetting down to the seed zone, especially where waterlogging occurs.
• Light/sandy/gravel soils
• Germinating seedling under stress (e.g. waterlogging, cold shock, insect damage).
• Maximum application rates.
• Marginal soil temperature at planting.
• Defined planting furrows that with rainfall, act to concentrate herbicide over the crop row.
• Shallow planting depth.

Factors reducing the chance of sorghum injury

• High quality seed, treated with Concep® II seed safener.
• Concep® II seed safener applied within the past 18 months.
• Closing up of the planting slot to avoid herbicide coming into contact with the sorghum seed.
• Excellent crop agronomy.

To keep upto date with this publication use the following link www.grdc.com.au/TT-KeepingSorghumSafe

Region North

• 1.51 mb Keeping sorghum safe 2016 northern (Web version) Tips and Tactics for keeping sorghum safe when using metolachlor-based herbicides.