Snow limits scouting but soil benefits from nitrogen
Jill Scheidt, agronomy specialist with University of Missouri Extension in Barton County, did not physically scout fields the week of March 27 due to the snow.
“Aphid threats still remain, and need to be scouted for in wheat fields. Aphids are active in temperatures above 60 degrees,” said Scheidt.
When temperatures drop below 60 degrees, aphids can be found at soil level or beneath soil level when it snows. Bird cherry oat aphids, green aphids identified by a red ring around their rear, are the most tolerant of aphid species.
“Dead aphids have been seen in area wheat fields. Cold weather does not usually kill aphids but as the season progresses, aphids lose their tolerance for cold temperatures, especially when temperatures frequently change 15 to 20 degrees, higher or lower, over a short period of time,” said MU state entomologist Wayne Bailey.
The recent snow could add a minor benefit to the soil by collecting nitrogen from the air and making the nitrogen more available to the plants.
Cold weather can have negative effects too, by temporarily binding nutrients and slowing the mineralization process. Cold temperatures may also slow root growth.
“Any uniform purpling of the leaves is likely due to a temporary phosphorus deficiency caused by cooler temperatures,” said Scheidt.
Also, the ideal time to apply nitrogen is early to mid-March; nitrogen applications should be done before jointing to prevent injury to wheat.
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.