The Effects of Arbuscular Mycorrhizal Fungi Inoculants on Pink Root and Onion Growth in Field Trials Near Connell, WA, 2016

This Plant Disease Management Reports article describes two 2016 field trials near Connell, Washington, evaluating two commercial arbuscular mycorrhizal fungi inoculants, MYKOS Gold Liquid and MycoApply Endo Liquid, on onion cultivars 16000 and Arcero. Researchers tested the inoculants with two liquid fertilizer rates at planting to determine effects on AMF root colonization, plant biomass, foliar nutrients, pink root severity, bulb firmness, and yield. In the Arcero trial, MycoApply Endo Liquid increased AMF root colonization significantly compared to the no-AMF control, but neither inoculant produced consistent improvements in stand, bulb yield, pink root severity, or firmness. In the 16000 trial, AMF root colonization remained very low regardless of treatment. Foliar nutrient effects were limited and inconsistent across cultivars and fertilizer rates. Overall, the trials showed no consistent benefit of either AMF liquid inoculant on onion performance under these field conditions, even where inoculation increased root colonization.