Monday, February 11, 2008

Turf and Landscape - Star of Bethlehem Control

Star of Bethlehem control has been difficult in the past. We now have some new herbicide tools for this problem weed. The following is an article on the subject.

STAR-OF-BETHLEHEM is a major perennial weed in turfgrass and landscapes. It is a bulbous perennial with fleshy grass-like leaves that grow up to a foot long with a whitish grooved midrib. From April to June, the plant produces bright white flowers with 6 oblong petals that have a distinctive green stripe underneath.

Star-of-Bethlehem generally dies back to underground bulbs during summer following seed dispersal. Ovate bulbs of Star-of-Bethlehem grow in clumps in the soil. Reproduction by seed is minimal but plants may germinate from dormant seed during spring months.

Controlling Star-of-Bethlehem is difficult since the plant can regenerate shoot tissue from vegetative structures following herbicide injury. Most pre- and post-emergence herbicides, including some non-selective materials, do not effectively control Star-of-Bethlehem. Glyphosate-containing products (such as Roundup®) often provide inconsistent and erratic levels of control and are not recommended. Multiple applications of diquat (Reward®) at 3 week intervals may effectively control Star-of-Bethlehem but may severely injure surrounding grasses and plants.

Recently, Research conducted at Virginia Tech University demonstrated that carfentrazone (Quicksilver T&O®) has substantial herbicidal activity on Star-of-Bethlehem and is safe on all cool-season turfgrasses. Applying Quicksilver T&O at 4 oz/acre once or 2 oz/acre twice at 3 week intervals gave 88 to 95% Star-of-Bethlehem control in tall fescue. Unfortunately, single applications of Quicksilver T&O® can not currently exceed 2.1 oz/A. In addition, Quicksilver T&O® is not systemic and Star-of-Bethlehem may continue to be problematic in successive growing seasons.

Reprinted from an article by Dr Steve Hart, Extension Ornamental and Turf Weed Specialist, Rutgers University.

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