Investigating the Prospect of Fine Fescue Turfgrass Seed Production in Minnesota

Abstract

The fine fescues (Festuca spp.) are a group of specialized cool-season turfgrasses that have consistently demonstrated average to exceptional quality across a range of minimally managed environments. Introducing commercial seed production of these turfgrasses in northern Minnesota is being considered because evidence suggests that consumers strongly desire and are willing to pay for the sustainable characteristics they possess. Fine fescue turfgrass seed has been historically difficult to produce successfully in Minnesota due to low yields and noxious weed infestations, but steady improvements in germplasm have encouraged agronomists to develop improved fine fescue seed production practices. Nitrogen fertility and safe herbicide use were investigated in fine fescue field experiments across Minnesota under the objective of determining whether commercial seed production is viable. Fertility management trials were established in three sites in Minnesota; St. Paul, Becker, and Roseau. Five taxa of fine fescue were tested: Chewings fescue (Festuca rubra L. ssp. commutata) ‘Windward’, strong creeping red fescue (Festuca rubra L. ssp. rubra) ‘Cindy Lou’, hard fescue (Festuca brevipila T.) ‘MNHD’, sheep fescue (Festuca ovina L.) ‘Quatro’, and slender creeping red fescue (Festuca rubra L. ssp. litoralis) ‘Shoreline’. Entries seeded in 2016 and grown for two seasons. Stands were managed under five nitrogen fertility management strategies, two fall-applied treatments of high (89.6 kg ha-1) and low (44.8 kg ha-1), and two fall and spring treatments of split high (44.8 kg ha-1) and split low (22.4) kg ha-1, and a control. All entries, except strong creeping red fescue ‘Cindy Lou’, had at least one seed yield meaningfully influenced by a nitrogen treatment. However, these seed yields were not affected consistently or in any pattern in any specific year and location combination. Hard fescue ‘MNHD’ had seed yields that were increased by an average of 250 kg ha-1 from the high and split high nitrogen treatments in two locations, Roseau and St. Paul, during the first harvest year compared to the control. Previous nitrogen fertility experiments showed that certain taxa and cultivars of fine fescues had a seed yield response from spring nitrogen applications of approximately 50 kg ha-1. Harvest index of all fine fescues, except strong creeping red fescue ‘Cindy Lou’ was also influenced in at least one year-location combination, similar to seed yield, not in any pattern or meaningful way. Thousand seed weight, panicle weight, spikelets per panicle, florets per panicle, and panicle density were variables measured in the 2018 growing season but ultimately not affected by any nitrogen fertility management treatment. The herbicide safety trial was established on Magnusson Research Farm using hard fescue ‘MNHD’. It was seeded in both 2015, from which two harvests were taken, and 2017, from which only one harvest was taken. Herbicide treatment applications consisted of effective turfgrass seed production herbicides clethodim, fluazifop, mesotrione, dicamba, 2,4–D amine, and a combination 2,4–D amine and dicamba, and a control. Seed yield, thousand seed weight, and germination of hard fescue ‘MNHD’ was severely reduced by the clethodim treatment in 2016 and 2018, both of which were first-year establishments. None of the herbicide treatments influenced hard fescue ‘MNHD’ in the 2016 growing season, the second year of the 2015 seeding. Past investigations have provided evidence that fine fescue’s susceptibility to certain herbicides can change depending on the age of the stand. Based on these field experiments fine fescue seed yields range between 500 and 1000 kg ha-1 in Minnesota. These seed yields reflect the averages of the competing regions of Oregon and Western Canada, and were achieved with and without the use of supplemental nitrogen applications. Therefore, the use of supplemental nitrogen may not be required to obtain these seed yields for a range of fine fescue taxa. Hard fesuce seed yield ‘MNHD’ may benefit from additional nitrogen amendments in first-year stands. Furthermore, ensuring the commercial value of fine fesuce seed harvests can be achieved through the application of most turfgrass seed production herbicides without damaging seed yield, weight, or germination.