Atypical myopathy-associated hypoglycin A toxin remains in sycamore seedlings despite mowing, herbicidal spraying or storage in hay and silage.

The study investigates whether three preventative strategies – mowing, herbicidal spraying, and storage in hay and silage – can reduce or eliminate the presence of hypoglycin A (HGA), a toxic substance found in sycamore seeds and seedlings that can harm horses, but finds that none are effective.

Research Methodology

• The experimental study involved testing three groups of sycamore seedlings with different treatments: mowing (6 groups), spraying with a dimethylamine-based herbicide (2 groups), or a picolinic acid-based herbicide (1 group).
• Samples of sycamore seedlings were collected at different times: before treatment, and then at 48 hours, and 1 to 2 weeks afterwards.
• The study also examined cut grass near the mowed seedlings, collecting samples before cutting and one week after.
• Lastly, the presence of HGA in seeds and seedlings processed into haylage and silage was also evaluated.
• The researchers used a validated LC-MS-based method to measure HGA concentration in the samples.

Research Findings

• The researchers found that neither mowing nor spraying herbicides significantly reduced the HGA content in sycamore seedlings up to two weeks after treatment.
• In fact, mowing temporarily caused a significant increase in HGA content in the seedlings.
• One week after mowing, the HGA concentration also significantly increased in grass that was cut along with the seedlings, though the levels were still low.
• Additionally, even after being stored in hay or silage for 6-8 months, HGA was still present in sycamore material. This finding suggests that pastures contaminated with sycamore material should not be used to produce hay or silage, as both seeds and seedlings in the bales could still pose a risk of intoxication.

Recommendations

• In light of these findings, the researchers concluded that the best current option to prevent HGA toxicity in horses grazing on contaminated pastures is mowing followed by the collection of sycamore seedlings.
• They also recommend against using pastures contaminated with sycamore material to produce processed hay or silage due to the ongoing risk of HGA intoxication.

Please note that the study only tested a limited number of herbicide compounds, so further research is needed to fully explore the potential of this intervention strategy.