Minnesota elevators that took wheat last year pleaded with farmers to be certain their wheat had a decent test weight of 58-60 pounds per bushel.
There were some real challenges with yields too, and that was hard because some people had just returned to growing wheat after a number of years away.
“It didn’t pencil, not even close,” said Jochum Wiersma, University of Minnesota Extension small grain specialist. Wiersma spoke recently at small grain meetings across the southern half of Minnesota sponsored by the Minnesota Wheat Research and Promotion Council.
The 2017 growing season yielded a record-breaking wheat crop across Minnesota – with yields averaging 67-68 bushels per acre in the northwest, 60 in West Central Minnesota, 58 in the south-central region, and 59 in the southwest.
The northwest region again experienced a good crop in 2018, with the yield averaging 59 bushels per acre – tying the state’s previous record.
Yields in the west central region were about 50 bushels per acre in 2018 – about 10 bushels per acre less than in 2017.
For the southwest region, yields averaged 20 bushels less per acre, with both the southwest and south-central averaging about 38 bushels per acre.
Wiersma thinks wheat yields suffered the least in the northwest because conditions were dry in July.
“Even though northwest Minnesota was hot in July, it was dry, which meant our dew points were lower, resulting in lower nighttime temperatures thereby preserving its yield potential,” Wiersma said.
Those statistics are backed up by information from the Minnesota Climate trend tool found at https://arcgis.dnr.state.mn.us/ewr/climatetrends/.
Five-month precipitation, April-August 2018
Northwest Minnesota – 10.13 inches, or 4.03 inches below average.
West Central Minnesota – 16.46 inches, or 0.79 inches above average.
Southwestern Minnesota – 25.17 inches, or 8.33 inches above average.
Southcentral Minnesota – 25.3 inches or 6.87 inches above average.
Wiersma heard of 48-54-pound test weights in wheat although kernel size looked normal. Leaf rust and powdery mildew were not major concerns, although tan spot and Septoria were present and could have reduced test weight.
Fusarium headblight was likely a major culprit, he said.
“You’ll see those chalky kernels in there, and then you’ll see some small kernels in that same head above it, right? It just didn’t fill out,” Wiersma said. “That will knock test weight and get you into that 52-pound test weight.”
He added that he’s seen wheat samples that didn’t look like Fusarium headblight, but still had shriveled kernels. He suggested late applications of glyphosate on soybeans may have caused injury to wheat – like an unplanned desiccation.
“I’m wondering, in some cases, if that glyphosate application coincided with the crop just being headed in the wheat and oats,” he said. “When those two coincide and you have some drift, you will see a completely normal crop, but the kernels will abort completely.”
Wiersma suggests studying wheat yield monitor maps. An indication of glyphosate drift would be some “straight lines” of lower yields.
“It might be diagonal, but there’s going to be a very distinct line somewhere in that yield map that shouldn’t be there,” he said. “It tends to be linear because for drift from Roundup to occur, it is a particle drift which means there has to be wind.”