St. Augustinegrass quality and nutrient content in response to granular and foliar iron, manganese, and magnesium

Iron, manganese (Mn), and magnesium (Mg) are common components of turfgrass nutrition programs. A 2-yr study was conducted simultaneously in Jay and Citra, FL, to determine the influence of Fe, Mn, and Mg on ‘Palmetto’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze.] quality and leaf nutrient concentration. Treatments included foliar Fe, Mn, and Mg sulfate and glucoheptonate; and granular Fe, Mn, and Mg sulfate and sucrate. Treatments were applied monthly from June to September during 2014 and 2015. Turfgrass receiving foliar Fe resulted in increased annual average turfgrass quality compared with untreated turfgrass in Citra during 2014 and in Jay during 2014 and 2015, which was associated with increased Fe in leaf tissue. Granular Mg did not influence turfgrass quality, whereas foliar Mg increased turfgrass quality by ∼10% during the last 4 wk of 2014 in Jay. Generally, foliar Mn did not influence turfgrass quality or tissue Mn concentrations, whereas granular Mn reduced turfgrass quality by ∼20% in Citra during 2015. Granular and foliar forms of Mn or Mg may not be warranted on turfgrass grown under similar conditions. Foliar Fe appears to be a reliable method of increasing St. Augustinegrass quality. Moreover, few differences were measured between foliar Fe sources, indicating that the least expensive foliar Fe source may be the most effective option for consumers. Evidence suggests that granular Fe does not improve turfgrass quality or tissue Fe concentrations and can therefore be removed from St. Augustinegrass nutritional programs without concerns of repercussions.