Weed Emergence in Winter Wheat
- Week of May 15, 2006

Last week I had a couple of producers from the southwest challenge me on the growth stage of the 5 wheat fields scouted below. It should be noted that all of the field locations scouted are from the counties of Huron, Perth, Waterloo and Wellington. Therefore it would be logical that wheat fields in those 4 counties would not be as far advanced as those counties in the southwest (i.e. Kent, Essex, Lambton and Middlesex).

Crop Staging and Weed Emergence

Crop Stage: All of the wheat fields are at Zadok's 32 (second node visible) and it is quite likely that the flag leaf will be visible within the next week.

Table 1. Growth stage, Zadok's Scale and Height of winter wheat
at 5 field locations on May 15th, 2006.

Weed Management Implications:

All of the scouted fields have received an herbicide application. Weeds that have emerged in the untreated areas of each field are shown below.

Weeds that Emerged this past week

• Lamb's-quarters
• Common chickweed
• Green foxtail
• Wild mustard
• Wild carrot

Figure 1. Sensitivity of spreading atriplex to
an application of bromoxynil/MCPA

Weed Growth Stage Progression:

Table 2. Weed species and growth stage at 5 winter wheat
field locations on May 15th, 2006 compared to May 8th, 2006.

Observations of Interest - Spreading Atriplex Control:

Although spreading atriplex was not observed within any of the wheat fields, there was a small patch on the border of 1 field where bromoxynil/MCPA was applied a few days earlier, and activity at this point looks promising (Figure 1).

What's next?

Seeds will be scouted in the treated and untreated portions of each field post-harvest to evaluate the benefit of herbicide applications in terms of seed production. Stay tuned for the results this fall!

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