Endophytes are naturally-occurring fungi that live inside the tissues of certain grasses. They benefit the grass by producing toxins that kill and repel many grass-feeding insects and provide resistance against certain diseases. They also make grasses more vigorous, more tolerant of heat and drought, and more competitive against weeds. In return, the grass provides the nourishment and the environment the fungi need to survive.
These beneficial fungi have been added to many lawn and turf grass varieties in recent years, and some of these varieties are now commercially available. If you are reseeding lawns or turf this fall, or installing new grassy areas, you may want to consider the possible benefits of purchasing grass seed that has been inoculated with endophytes.
Some of the insect pests and turf diseases that are controlled or reduced by endophytes include cutworms, sod webworms, aphids, and most insects that feed on the crown and lower stem of grasses. Endophytes are also found in the root system, but have variable effects on root-feeding pests such as grubs: sometimes they help, sometimes they do not. Endophyte-induced resistance to diseases has not been well documented at this time. It has been reported that dollar spot, leaf spot, stem rust, and brown patch might be reduced by endophyte inoculation.
Not all turf varieties can be inoculated with endophytes, but new ones are expected to be available soon. Tall fescue, perennial ryegrass, and fine fescue are some of the grass species for which endophyte-inoculated varieties are commercially available. Unfortunately, endophytes that can survive in Kentucky bluegrass have not yet been found, but researchers hope to soon discover a strain that will work.
A caution when considering the use of endophyte-inoculated grass is that the toxins produced by endophytes can be toxic to livestock that graze the plants. Do not plant endophyte-inoculated grass where horses or other livestock might eat it. The toxins are harmless to humans and non-grazing animals.
When purchasing grass seed that contains endophytes, check the lot numbers to make sure the seed is fresh because the endophytes may die after storage of two years or even less. The grass seed may still be viable, but the fungi may not be.
References:
Danneberger, T.K. 1993. Turfgrass Ecology and Management. G.I.E. Inc., Cleveland, OH. 201 pp.
Written by Sherry Lajeunesse, Extension Urban Pest Management Specialist. Sept., 1997