Yellow nutsedge emergence

On April 7 I was notified by two separate nurserymen that nutsedge had emerged in each of their fields. Both nurseries are located near Salem, OR.

I scouted several fields at both nurseries. It seems the nutsedge emerges first in sandy, recently cultivated (cultivated this year), and irrigated fields. Both nurseries had sandy soils; however, fields at both nurseries that were either not irrigated or cultivated did not have any emerged nutsedge (none that I could find).

The image to the right was taken on Friday, April 9, 2004.

 

Nutsedge emerges from underground tubers. Virtually all tubers are within the top 12 inches of soil.

Tubers germinate when soil temperatures are sufficiently high. Research in California used degree day models to predict nutsedge emergence. A simpler, and perhaps more reliable indicator is to use landscape plant phenology.

According to a local nurseryman, pie cherries bloom just before yellow nutsedge emergence. Herbicides containing metolachlor (Pennant) provide effective preemergence nutsedge control. These herbicides have to be applied prior to nutsedge emergence. Timing applications with the onset of cherry bloom will help time herbicides correctly. I've also noticed that established landscape Kwansan cherries are in full bloom just a week or so before reports of emergence.

 

Pie cherrie orchards bloom just before nutsedge emergence, and can be a useful tool for timing preemergence herbicide (Pennant) applications.
I know very little about cherry orchards, but I have been told that not all cherries bloom at the same time. Also, when using these types of phenological indicators, observe mature landscape or orchard plants. Do not rely on container-grown, or recently planted trees because often they flower earlier or later than normal.

See other nutsedge characteristics

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