Endophytes As Biological Control Agents of Dandelions (Taraxacum officinale) in Turfgrass Systems.

The increasing prevalence of bans and restrictions on cosmetic pesticide use has significantly reduced the palette of weed control options available for turf systems. Thus, new weed-management strategies are required. The application of microorganisms to control weeds is a potential alternative to traditional herbicide use. Previous research has demonstrated that the introduction of beneficial endophytes (microbes that inhabit plants without causing disease) during establishment of grass-based pastures can reduce the encroachment of weeds. This project has investigated the possibility of translating this phenomenon to controlling dandelions (Taraxacum officinale) in turfgrass systems.

238 endophytes isolated from monocot species were screened for the ability to suppress germination of two different dandelion accessions in sterile agar culture. Three candidates were discovered in this process and were subseqently tested on common turf species including creeping bentgrass (Agrostis stolonifera), Kentucky bluegrass (Poa pratensis), creeping red fescue (Festuca rubra), and annual ryegrass (Lolium rigidum) in sterile agar and in a mixture of sand and turface. The candidate endophyte treatments reduced the germination rates of all species tested, however the degree to which this effect occurred varied between species. The greatest reduction was observed in dandelion and the least reduction was observed in creeping bentgrass. In general, greater reductions of germination were observed on sterile agar than on the sand/ turface mixture. No effects on germination have been observed in association with any of the candidate endophytes when tested in field soil.