The following information is a Web Extra from the pages of Farm Journal. It corresponds with the article "Make Your Weeds Queasy." You can find the article in Farm Journal's 2013 Seed Guide.
The Weed Science Society of America recently published a report with the following 12 best management practices for targeting resistant weeds:
- Understand the biology of the weeds present.
- Use a diversified approach toward weed management focused on preventing weed seed production and reducing the number of weed seed in the soil seedbank.
- Plant into weed-free fields and then keep fields as weed free as possible.
- Plant weed-free crop seed.
- Scout fields routinely.
- Use multiple herbicide mechanisms of action (MOAs) that are effective against the most troublesome weeds or those most prone to herbicide resistance.
- Apply the labeled herbicide rate at recommended weed sizes.
- Emphasize cultural practices that suppress weeds by using crop competitiveness.
- Use mechanical and biological management practices where appropriate.
- Prevent field-to-field and within-field movement of weed seed or vegetative propagules.
- Manage weed seed at harvest and after harvest to prevent a buildup of the weed seedbank.
- Prevent an influx of weeds into the field by managing field borders.
More Weed Seed Control Tips
In addition to tillage and herbicides, other basic practices can help farmers manage weed seeds. They include:
Identify the weeds in your field and know their weaknesses. Are they dioecious (as with waterhemp, whose male plants make pollen and female plants make seeds) or monoescious (as with giant ragweed, whose plants contain both male and female flowers)? What growing conditions allow them to thrive? Pigweeds require a lot of light to germinate, for example, so maintaining a good stand of corn or beans can limit the sun’s ability to penetrate the canopy. In general, bigger weed seeds remain viable in the soil longer than smaller seeds.
Explore the edges of your fields and identify ways to keep weed seeds from moving in from the outside.
Consider how weather conditions can help or hurt your weed seedbanks. For example, fields left unattended during the drought of 2012 allowed weeds to flourish. Routine field management can limit the seed population in your soil so it doesn’t get out of control.
Choose chemicals wisely. Translocated herbicides can be a good choice during post-harvest applications because they move through the weed and attack the root system, where the plant stores much of the food it makes through photosynthesis.
Avoid spreading manure collected from livestock that have consumed feed grains that have not been cleaned. Consider composting animal manure and carefully sourcing feed. Resistance problems, particularly with Palmer amaranth, can be expedited with careless spreading, creating the risk that crop acreage will be put out of production.