Ground ivy (Glechoma hederacea) control with boron and iron in Kentucky bluegrass turf

Ground ivy (Glechoma hederacea L.) is a perennial broadleaf weed in the mint family (Lamiaceae) that is commonly found in turf in the temperate climates of the United States. Cultural practices that maintain dense turf are the best way to reduce weeds; however, cultural control methods alone cannot provide complete weed control. Herbicides are commonly used to control weeds in the turfgrass industry, but interest in alternative control methods is increasing. Applications of iron-based products are an alternative chemical weed control option in turfgrass systems, but other micronutrients, such as boron, may also be a viable option. The objective of this study was to compare the efficacy of a chelated iron product as well as different boron-based products for ground ivy control and also determine if these products injure Kentucky bluegrass (Poa pratensis L.). The products evaluated included borax, boric acid, Solubor (disodium octaborate tetrahydrate), and Fiesta (FeHEDTA) with a low and high rate tested for each. Ground ivy cover was reduced 77% or more from a single October application of all boron sources at the high rates and the high rate of Fiesta when evaluated 9 months later. The high rate of all boron-containing products caused unacceptable turfgrass injury (<7) and reduced turf quality below acceptable levels (<6). No turfgrass injury or reduction in turf quality was observed in the Fiesta-treated plots. These results indicate that applications of the micronutrient boron can be used to control ground ivy, but not without causing injury to Kentucky bluegrass.