New green herbicide offers hope against “heartbreaking” invasive weed

Crested floatingheart plants are a decidedly poor choice for Valentine’s Day, scientists with the Weed Science Society of America (WSSA) say. This showy ornamental is a native of Asia and a popular selection for water gardens – prized for its large, heart-shaped leaves with a deep red border. Unfortunately, though, crested floatingheart can wreak havoc as a weedy aquatic invader if it escapes into natural settings.

Dense, vegetative mats formed by the plant can blanket canals, reservoirs and other bodies of water – degrading fish habitats, causing flooding, and interfering with recreational activities like swimming and boating.

Crested floatingheart is also notoriously hard to control. It can reproduce both from leaf fragments and from fingerlike ramets, which are vegetative structures that form underneath its leaves.  

“Our lab studies show that on average, one crested floatingheart plant can produce 500 ramets in just six months,” says Lyn Gettys, PhD, an associate professor at the University of Florida. “Forty to 60 percent of those ramets will then sprout and produce ramets of their own, fueling exponential growth. Over a two-year timeframe, that can conservatively translate into about 80,000 new plants from a single mother plant.”

Attempts to mechanically remove crested floating heart infestations can be heartbreakingly ineffective. Leaf fragments and ramets can simply sink to the bottom of the body of water and produce new plants. Until recently, few herbicides were available to control the weed effectively.

Those options were expanded, though, with the introduction of florpyrauxifen-benzyl, an active ingredient registered for the control of hydrilla. Aquatic pest managers have recently discovered that florpyrauxifen-benzyl can also deliver a knockout punch in the fight against crested floating heart. “It’s a real game-changer,” Gettys says.

The new chemistry is applied at very low rates. It has low persistence in soil and water and exhibits low toxicity to birds, insects, fish, and other organisms. As a result, it has won multiple awards, including a Green Chemistry Challenge Award. “The goal now is to use the herbicide responsibly to avoid the evolution of herbicide resistance,” Gettys says.

One of the most important strategies, she says, is to focus on prevention. Look for native plants for your water garden instead of exotic imports like crested floating heart. And when you are enjoying water sports on a lake, reservoir, or other body of water, thoroughly clean and dry your boat and other sports equipment so you won’t accidentally transport aquatic invaders to a new site.

For more information:
Weed Science Society of America 


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