By Garett Heineck
A lush green lawn has been a trademark of American society since the mid 20th century, offering increased aesthetics and comfort to homes. However, now more than ever homeowners and professional turf managers are looking for ways to increase quality of turfgrass with fewer inputs. Increasing productivity can come from improved genetics, more effective and efficient cultural practices and endophytes.
Endophytes, as they pertain to turfgrass, are intercellular fungi that form mutualistic relationships with many turf species. Turf species that commonly benefit from endophytes are perennial ryegrass, tall fescue and fine fescue. Common lawn species like Kentucky bluegrass are not compatible with endophytes due to high host specificity. Endophytes survive within the plant by utilizing energy produced by the plant and in return provide the host plant with numerous benefits. Toxic compounds, chiefly the alkaloids peramine and loline, produced by endophytes can deter insect herbivory in turfgrass stands (Bush et al., 1997). Endophytes have also been shown to increase a turfgrass stand’s ability to resist heat stress in species such as tall fescue and perennial ryegrass (Kane, 2011). In fine fescues, endophytes suppress some fungal pathogens such as dollar spot (Ruemmele et al., 1995). These benefits generally come with little expense to the plant due to the fact that it is not in the best interest of the endophyte to take more than its share of the available energy because the endophyte relies on the plant for survival and reproduction. Endophytes also produce several mildly toxic alkaloids that can deter insect and animal feeding. In pasture or hay production systems this can be of some concern, but these should not concern homeowners.
Symbiotic fungal relationships can be beneficial to turf managers by allowing them to reduce inputs such as water and pesticides. However, not all turf species are compatible with endophytes. Furthermore, not all varieties that benefit from endophytes are infected with viable (alive within seed) endophyte. Because endophytes are important, there are a few things that you need to keep in mind when using endophyte infected grass seed:
1) Check to see if the species you intend to seed can be infected with endophytes (i.e. tall fescue, fine fescue and perennial ryegrass).
2) Check the variety bag or label for the phrase “Endophyte Enhanced,” as this is a good indicator of endophyte infection.
3) Use the seed as quickly as possible to retain its viability or store it at appropriate temperatures. Research has shown that viability can be retained for over two years when stored at temperatures below 4o C (~40o F). Poor seed storage will drastically reduce endophyte viability so make sure the seed source is reliable (Tian et al., 2013).
Turfgrass scientists at the University of Minnesota are looking for ways to develop lower input turfgrasses that provide important functions while retaining acceptable aesthetics. For example, breeding in perennial ryegrass has implemented or improved traits such as Assure herbicide tolerance, turf quality, winter hardiness and disease resistance. Our program is looking forward to upcoming variety releases and the significance of ensuring not only superior genetics but also superior endophyte effectiveness is not being overlooked. This involves research in understanding of complex endophyte by plant interactions and implementing superior endophyte strains. Combining research in genetics and endophytes could guarantee increased endophyte quality along with the superior plant performance for which UMN varieties are already known.
Bush, L.P., H.H. Wilkinson, and C.L. Schardl. 1997. Bioprotective alkaloids of grass-fungal endophyte symbioses. Plant Physiol. 114(1): 1.
Kane, K.H. 2011. Effects of endophyte infection on drought stress tolerance of< i> Lolium perenne</i> accessions from the Mediterranean region. Environ. Exp. Bot. 71(3): 337–344.
Ruemmele, B.A., L.A. Brilman, and D.R. Huff. 1995. Fine fescue germplasm diversity and vulnerability. Crop Sci. 35(2): 313–316.
Tian, P., T.-N. Le, K.F. Smith, J.W. Forster, K.M. Guthridge, and G.C. Spangenberg. 2013. Stability and viability of novel perennial ryegrass host–Neotyphodium endophyte associations. Crop Pasture Sci. 64(1): 39–50.