Thursday, March 21, 2013

Field Scouting Report for March 20…Henbit, Chickweed and Cold Weather Purpling Seen in Southwest Missouri Wheat Fields This Past Week

Contact: Jill Scheidt, agronomy specialist
Tel: (417) 682-3579

The weekly crop update for March 20 provided by Jill Scheidt, agronomy specialist with University of Missouri Extension in Barton County, notes that henbit and chickweed is starting to show up in southwest Missouri wheat fields.

“Annual weeds such as henbit and chickweed can cause up to a 37 percent yield loss in wheat,” said Scheidt. “Harmony or its generic is recommended to treat henbit and chickweed.”

A uniform purpling was seen on wheat tillers this week. The purpling could be due to a temporary phosphorus deficiency that has occurred during the cold weather snap. It could also be due to slight freeze injury.

“Plants must be tested to determine which possibility it is. Purpling will lessen as temperatures rise,” said Schedit.

Scheidt says aphids were also seen this week, but no bird cherry oat aphids, which vector barley yellow dwarf virus. Aphids are green insects found on the underside on the leaf or in cold temperatures, at soil level, near the crown.

Bird cherry oat aphids can be identified by a red ring around their rear with cornicles which look like tail pipes. Threshold levels for bird cherry oat aphids are 6 aphids/foot. A rate of 3.2 oz/A Warrior or 3.6 oz/A Mustang Max is recommended to control aphids.

“Early-mid March, before jointing, is the ideal time to apply nitrogen. In a drought year, less nitrogen may be required when planting after corn,” said Scheidt.

Formula: Nitrogen applied to corn- bushels/acre harvested= possible left over nitrogen. Possible left over nitrogen X .9 = total nitrogen needed to apply to wheat field

“It is a good idea to still apply the normal amount you usually apply to at least half the field. If you see that the part of the field you applied with less nitrogen is less green; then use the normal rate you usually apply,” said Scheidt.

The weekly field scouting report is sponsored by University of Missouri Extension and Barton County Extension.

For more information on this scouting report, or to learn how you can receive it a week earlier by telephone, contact the MU Extension Center in Barton County at (417) 682-3579.


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