Infected-not infected: Factors influencing the abundance of the endophyte Neotyphodium lolii in managed grasslands

Temperate grasses are infected with endophytic fungi of the genus Neotyphodium. These fungi asymptomatically live inside the plant's tissue enhancing resistance of their hosts to herbivores and abiotic stresses. Perennial ryegrass (Lolium perenne), infected with Neotyphodium lolii can be detrimental to grazing livestock causing a neural disease. This study aimed at determining the impact of grassland management on fungal incidence. In a rural district of Central Germany 90 sites differing in land use intensity (extensive, intermediate and intensive) and grassland use (pastures, mown pastures, and meadows) were investigated for the presence of N. lolii. Infections were detected in 41% of the sites sampled, but overall infection rates were low (5.8 ± 9.2%). Neither the intensity of land use nor the type of grassland influenced endophytic incidences. In contrast, the geology of the sampled sites had a significant impact on the incidence of N. lolii. Grass tillers collected from limestone sites showed significantly higher infection rates than from other soils. We hypothesize that the low field capacity and high amount of potassium on limestone sites favored the survival of infected grasses under drought stress. Therefore, geology should be taken into account when considering management strategies for this endophytic fungus.