Joel Ransom, NDSU Extension agronomist, says he's been asked what the yield potential is of small grains in the latter half of June.
That's really late.
"Unfortunately, I could not find any recent field experiments that included these very late planting dates," Ranson writes a recent issue of the North Dakota Crop and Pest Report. "However, the general rule of thumb is that there is a 1.5% reduction in wheat, 1.7% reduction in barley, and a 1.2% reduction in oats for every day in delay beyond the optimum planting date. Data based on reported planting dates and subsequent yields at the farm level in Manitoba suggest yield losses of about 1.3% per day delay, though the optimum planting date is generally later than those in ND (see http://www.gov.mb.ca/agriculture/crops/cropproduction/pdf/faa22s06.pdf.
Assuming that planting can resume during the 2nd week in June and using a 1.3% yield loss per day delay, estimated yields for small grain crops would be about 55% of the optimum for the northern tier of the state, and only 27% of the optimum in the southern tier of the state.
Planting wheat during the 2nd and 3rd weeks of June is not unheard of in northern North Dakota, especially in the northwest region of the state, Ranson says. There there is some anecdotal evidence that suggests yields might be even better than those the yield formula indicates.
An additional concern when planting small grains in mid to late June in northern ND is the risk of frost before maturity. Spring wheat planted by the 21st of June would normally be expected to mature by the first week of September, a week or more ahead of the average date for the first frost in that region.
"Before deciding to plant a small grain crop in mid to late June, carefully consider the costs and the potential benefits. Since yield expectations are likely to be significantly less than when planting at an optimal date, reduce N fertilizer rates accordingly," he advises.