Recently, strains of N. coenophialum have been isolated from wild tall fescues growing in the Mediterranean region and artificially inoculated into elite tall fescue cultivars (see Chapter 19). These strains were selected because they result in low to nil levels of ergot alkaloids, yet retain many of the beneficial traits conferred to the plant-endophyte association, such as drought tolerance (see Chapter 4) and insect resistance. One of these novel endophytes (AR542) has been released by Grasslands AgResearch in New Zealand under the trademarked name MaxQ (Pennington Seed Co., Madison, GA). Commercially, MaxQ was inserted into either Jesup or Georgia 5 tall fescues. The lesion nematode (Pratylenchus spp.) was associated with poor stand performance of MaxQ at Tifton, GA (Timper, unpublished data, 2000). In a greenhouse experiment, reproduction of P. scribneri in plants infected with either AR542 or another nontoxic strain (‘AR584') was not different from that in E- plants (Timper et al., 2005). Because ergot alkaloids are not likely to be involved in nematode resistance in tall fescue, it should be possible to identify nontoxic strains that also confer resistance to nematodes. Identifying the mechanism by which the endophyte suppresses nematode infection and reproduction will aid in the selection of resistant tall fescue-endophyte combinations.


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