Effects of fungicide treatment on transmission of <i>Epichloë</i> endophyte in rye (<i>Secale cereale</i>)

<p dir="ltr">Seed-borne asexual species of <i>Epichloë</i> fungal endophyte have proven to be of critical importance in temperate grasses, particularly those grasses sown in pastures in the USA, New Zealand and Australia. These obligate mutualistic fungal endophytes impart benefits to the host plant through enhancing the plant’s ability to counter various abiotic and biotic stresses. Although there may be detrimental effects on livestock, selected endophytes have been identified and used to address animal health and productivity issues, while still providing protection to the host grass from stresses. </p><p dir="ltr">The use of selected endophytes has also been explored for cultivated cereals such as rye and wheat (<i>Triticum</i> spp.), with the goals of reducing usage of fungicides and insecticides, and improving the plants tolerance of abiotic stresses. A complicating factor is that fungicides may still be required for crop management, which in turn could be detrimental to the <i>Epichloë</i> endophyte. While this issue has been studied for pasture and amenity grasses, no similar studies have been performed with endophyte-infected cereals. Fungicide treatments, representing a total of five chemical families, were applied either to seed prior to sowing or to foliage of established crops of rye infected with selected strains of <i>Epichloë bromicola</i> (AR3002) or <i>Epichloë bromicola </i><i>× amarillans</i> (AR3068). In a field trial, two spring applications of five foliar-applied fungicidal products had no detrimental effect on transmission of endophyte to seed (seed-borne endophyte), but one combination did result in 8% lower viable endophyte in the seed. In a greenhouse trial, three seed-applied fungicidal products had no detrimental effect on transmission of endophyte from seed to seedlings. These results demonstrate that if fungicides are required, then options are available that will not adversely affect the <i>Epichloë</i> endophyte. In addition to further work on rye, the effect of fungicides on <i>Epichloë</i>-infected wheat requires investigation.</p>