Propyzamide stewardship
Stewardship campaigns are fundamental to combating concern about autumn and winter applied herbicides reaching watercourses. It is crucial that operators follow product guidance to help secure continuing access to important chemistry.
Propyzamide is a key ingredient in grassweed control strategies, particularly blackgrass, in oilseed rape. With no known resistance, it can help manage and reduce the blackgrass burden across the rotation.
“Propyzamide works best when applied to cold, moist soils, but this must be balanced with the need to protect water,” says Clare Stapley, Corteva’s oilseed rape category marketing manager.
“To attain best control, soils should be at 80% field capacity (1-2.5cm of moisture), soil temperature at 10°C and declining, and an appropriate rate should be selected,” she adds.
Unfortunately, this means the optimum application window is from October to January – some of the wettest months of the year.
Best timing
Growers should focus on using the right rate, in the right conditions and at the right time, she adds. The appropriate temperature range for applications often occurs on or after 5th November, so growers are advised to be ready, but resist the temptation to apply outside of the ideal conditions.
Data demonstrating the correlation between application date, dose rate and blackgrass control reaffirms the importance of waiting for the optimum conditions.
“Only use the maximum rate of 840gai/ha for severe blackgrass situations. A rate of 750gai/ha or 500gai/ha are recommended for less-severe blackgrass or other grasses and broad-leaved weeds. Only use one product containing propyzamide per crop per year,” explains Clare.
Corteva also recommends only using one product containing propyzamide per crop per year.
Best practice guidance
To help growers achieve the best efficacy and protect water, Corteva has introduced a new Knowledge Hub. This promotes best practice when using Astrokerb and Kerb Flo 500, which both contain propyzamide. These products have grown in importance in the past decade because they retain the ability to take out grass weeds, most notably graminicide-resistant blackgrass.
The new Knowledge Hub can be found HERE
This provides detailed information about propyzamide as well as guidance about its use and stewardship. A straightforward three-step process offers best practice advice about the ‘right rate, right conditions and right time’.
Here operators can also find links to its free Kerb Weather data App and Corteva Arable App, which are designed to help with the application decision making process.
Right rate
Assess black grass population and select appropriate dose rate.
• 750g ai/ha good control
• 840g ai/ha gives more robust control especially in heavy blackgrass populations.
Right conditions
Apply when soil temperatures are declining and there is sufficient moisture.
• Optimum temperature is 10°C and declining at 30cm soil depth
• Adequate soil moisture is essential to move the chemical into the root zone of weeds.
Right time
Trials have shown the best time to apply tends to be end October to November, because this is the time where soil temperatures are falling and are ideal for propyzamide application.
Water Protection
It is recommended operators download and study the propyzamide Water Protection Advice Sheet (WPAS) from the Voluntary Initiative website HERE
This explains after heavy rain events there is a risk that propyzamide could get into surface water from field run-off or through field drains. Appropriate planning, management, and adoption of stewardship practices must be followed to reduce this risk.
The WPAS also urges operators to consider all the risks and follow basic water protection advice:
- Take care when filling and cleaning the sprayer
- Use a 6m grass buffer strip, or 5m no-spray zone, beside watercourses
- Discuss cultivation and spray timing with your BASIS registered adviser
- Manage soils and tramlines to avoid surface run-off or erosion
- Do not apply when soils are cracked, dry or saturated.
- Do not apply propyzamide if heavy rainfall is expected within 48 hours of application.
