By mid December most southern Victorian maize silage paddocks will have been sown, so follow up weed control checks are the next important stage to ensure farmers protect yield potential and crop net returns.
Pre-emergence herbicides like s-metolachlor and atrazine are highly effective in controlling the majority of early weed flushes in maize, forming the backbone of a strong weed management program.
These herbicides provide broad-spectrum control, targeting weeds before they emerge and reducing early competition. However, the temperate climate in southern Victoria often allows for secondary weed germinations later in the season. Despite the effectiveness of pre-emergence applications, some resilient or later-germinating weeds can still break through, necessitating timely post-emergence interventions to ensure the field remains weed-free during critical growth stages.
- Early control helps protect yield potential of the crop.
- Small weeds are easier to control.
- Young weeds absorb and translocate herbicides better.
- Herbicides can be less effective during times of heat and drought stress, which often occur at later application times.
Why early post emergent weed control is important!
Weeds compete with maize for nutrients, water, and light, particularly during early growth. Timely management enhances crop performance and profitability.
- Yield Protection: Weeds reduce yields when competing with maize during early growth.
- Efficiency: Younger weeds are easier to control with herbicides and cultivation.
- Resource Use: Weed-free fields improve maize access to nutrients and water.
Critical Timing
Research indicates that in maize, weeds can begin to impact yields as early as the V2 stage (second leaf stage). Therefore, controlling weeds before this stage and maintaining a weed-free environment through at least the V14 stage (fourteenth leaf stage) is essential for preserving yield potential.
Chemical formulations such as Dicamba has a broad spectrum of broadleaf weeds, whilst Atrazine has some impact on emerging grasses. The good thing for farmers are there are options to control weeds whilst they are young and not impact overall crop yield.
Southern Victorian Climate
Our local temperate climate fosters multiple weed flushes, requiring vigilant management for multiple germinations.
This is why pre and post emergent sprays are so important. Silage growers must continue their control methods, using pre-emergence and post-emergence tactics to match the timing of weed emergence.
We also need to be sustainable with our weed control. Integrating crop rotation during the winter with species other than grasses and varied herbicide modes of action helps combat persistent weed issues and herbicide resistance long term.
Conclusion
Effective early weed control maximises maize yield and sustainability. Combining timely herbicide application, cultural practices, and local adaptation ensures success.
