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Prairie Junegrass, Koeleria macrantha, is a native, perennial, cool season, mid grass, monocot, of the grass family that is common on healthy mixed grass prairie plant communities. Prairie Junegrass can grow on sandy, shallow, silty, and thin claypan ecological sites. It has greater percent present on the silty site and greater basal cover on the shallow site. The greatest percent present and basal cover were on the twice-over management treatment.
Early season activity starts with regreening with active chlorophyll the portions of the carryover leaves that have intact cell walls from the previous growing season vegetative tillers, secondary tillers, and fall tillers. The green portion of the carryover leaves provides large quantities of carbohydrates and fixed energy for the production of new leaves.
New leaves of Prairie Junegrass are visible between 8 and 13 April. Prairie Junegrass lead tillers are derived from carryover vegetative tillers and produce 3.5 new leaves on 1 June consistently, and can be used as a reliable indicator of grazing readiness. Lead tillers at the 3.5 new leaf stage are physiologically capable of positive response to partial defoliation of 25% to 33% of leaf weight by graminivores. The tallest basal leaf is at 85.0% of maximum height on 1 June and the lead tiller contains 15.1% crude protein and 0.22% phosphorus on the silty ecological site during early June.
The flower stalks reach the boot stage around 16 to 22 May, reach head emergence on 5 to 6 June, and reach the early flower stage around 19 to 26 June, with a 5 week flower period from early June to mid July.
Leaf growth in height is rapid during May, growth is slower during June, and slower still during July. Basal leaves reach 93.0% of maximum height by end of June and reach 100.0% of maximum height by late July.
Seeds are developing between 26 June and 17 July and being shed during 16 July to 11 August. Seed stalks reach maximum height at the end of June and lead tillers contain 11.3% crude protein and 0.234% phosphorus.
Lead tillers drop below the crude protein requirements of lactating cows during the first week of July and drop below the phosphorus requirements during the second week of July. Leaf dryness starts 14 August and continues through August into September. Lead tillers of Prairie Junegrass contribute little to forage value after mid July.
Vegetative tillers are derived mostly from secondary carryover tillers that were most likely fall tillers from the previous growing season and some are derived from early season initiated tillers. Vegetative tillers have slightly slower growth rates than lead tillers during the early portion of the growing season.
Vegetative tillers reach the 3.5 new leaf stage shortly after the lead tillers and become independent. When lead tiller growth rates decrease greatly during early July, the vegetative tiller growth rates do not slow down. Grazing management practices that have less than 100 lbs/ac of available mineral nitrogen have less than a third of the quantity of vegetative tillers as grazing management practices that can produce greater than 100 lbs/ac available mineral nitrogen. Vegetative tillers provide around three fourths of the forage weight after mid July.
Secondary tillers are derived from growing season initiated tillers. With most useful tillers initiated during May and June. Few secondary tillers are initiated during the period when lead tillers have high resource demand as they progress through the flower stage and seed production. Most of the secondary tillers on traditional grazing practices are at less than the 3.5 new leaf stage and are terminated during the high resource demand period resulting in only about 3% surviving secondary tillers compared to the quantity of surviving tillers on the twice-over system.
Surviving secondary tillers become independent of the lead tillers when the fourth new leaf is near full development. These early initiated secondary tillers contribute to the forage weight after mid or late July. The quantity of vegetative and secondary tillers, and the quantity and quality of forage after mid July depends on the type of grazing management practices used during June and the first two weeks of July.
Traditional grazing practices have low quantities of forage value vegetative and secondary tillers after mid July, and lactating cows are grazing forage that is below their nutrient requirements. Prairie Junegrass is a valuable asset on the Northern Mixed Grass Prairie.
For more information Go To:
https://www.ndsu.edu/agriculture/ag-hub/publications/dickinson-rec-2018-annual-report
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