Timing is key for weed management


ITHACA, NY – Farmers can tailor their efforts to control weeds more effectively by identifying when a particular weed will emerge, according to a new study from Cornell University.

Researchers from the College of Agriculture and Life Sciences reviewed previous studies on the peak timing of emergence of 15 troublesome weed species in the Northeast, as well as potential ways to using this knowledge, in their study, “Improving Weed Management Based on the Timing of Emergence Peaks: A Case Study of Problematic Weeds in Northeast USA,” published in the journal Frontiers in Agronomy.

“There are many different weed management tactics, and most of them can be improved by considering what weed species you have and when they emerge,” said lead author Bryan Brown. , integrated weed management specialist for New York State Integrated Pest. Management and Adjunct Assistant Professor in the Horticulture Section of the School of Integrative Plant Sciences, College of Agriculture and Life Sciences. “In this article, we’ve provided a framework starting with the tactics that are easiest to adapt or adjust — all the way to redesigning a cropping system — based on avoiding certain weed species.”

As an example, Brown cited common ragweed. “We found that in most publications, common ragweed was finished emerging by June 1,” he said. “So if you’re able to wait to plow and plant your field past June 1, you’ve effectively avoided common ragweed for the season.” Conversely, if a field is riddled with mid-season or late-season weeds, planting earlier can help give crops a head start to outperform them.

When it comes to controlling weed seedlings with herbicides or shallow tillage, control is most effective soon after weeds emerge, so know when different weed species grow can help farmers plan ahead.

Farms with flexible crop rotations may leave the ground bare, or perhaps a cover crop, for when their most problematic weed emerges. By controlling this species, they are essentially removing its weed seeds from the ground so it will be less of a problem in the future.

The researchers found that the timing of weed emergence varied across previous studies due to factors such as weather conditions, soil temperature and humidity.

“Naturally, this is going to vary from year to year and from study to study,” Brown said. “But the big surprise for me was that among previous studies that modeled weed emergence, when we entered identical weather data, there were still variations in when they expected weeds to emerge. This highlights regional differences in soils and weed genetics.

As models improve by incorporating regional differences, the researchers hope to work with the Network for Environmental and Meteorological Applications to give farmers direct access to weather forecasts of weed emergence.

“As weed management becomes more difficult, I think this type of planning is going to become more important,” Brown said. “Hopefully, as these emergence patterns become more accurate, we can use these tactics to even better utilize and really refine the timing of our weed management.”

This work was partially supported by a joint research and extension grant that the Cornell University Agricultural Experiment Station and the Cornell Cooperative Extension received from the National Institute for Food and Agriculture of the United States Department of Agriculture.

– This press release originally appeared on the Cornell University website


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