A pasture is to a horse what a buffet is to a human; what it sees is what it eats. And like humans, the healthier the buffet option, the healthier the horse. Horses, as we know, are herbivores who require a diet rich in grasses and herbs. Where there is grass, however, there are also pesky weeds. Some weeds are harmless, causing only minor distress to the digestive system of a horse. Some property owners choose to apply herbicides to their fields to control these weeds. Glyphosate and phenoxy herbicides are most commonly used. In 1974 in the United States Monsanto commercialized a popular glyphosate-based herbicide called Roundup. This invention gave farmers access to weed-free fields indefinitely. According to Monsanto, glyphosate is a breakthrough in farming. The company claims that glyphosate products work well on ridding weeds, but they also help to “grow crops more sustainably” by allowing for less disturbance of the soil itself.
Hazards of Glyphosate Herbicides
From an outside perspective, glyphosate-based herbicides seem to be the end-all-be-all of producing weed-free pastures and crops for horses to feed. So what’s the catch? The use of herbicides in our ecosystem have put many lives, including your horses at risk. While Monsanto claims their product is safe for consumption, science disagrees. Several major health problems are related to the increased consumption of glyphosate-based herbicides such as Roundup. The exposure to the chemical herbicide put horses at risk for diarrhea, colic, inflammatory bowel disorders, endocrine disorders, fertility problems, impaired nutrient absorption, cancer, and more. When Roundup is applied to horse pastures and is found on the food consumed by the horses via soy, oats, barley, corn, wheat, peas, carrots, alfalfa, and grass hay, it can be contributing to serious harm for your horses. So what are the other options? Are they as hazardous as glyphosate-based herbicides?
Other common pasture herbicides include:
1. Lorsban — This is an herbicide that has a 7-day grazing and 30-day haying restrictions, meaning a horse must be absent from its pasture for at least 7 days before grazing. According to the toxicity sheet, Lorsban is fatal/poisonous if swallowed or absorbed through the skin. It is extremely toxic to fish and aquatic organisms and mammals and must be kept away from water by all means possible.
2. Dicamba — This herbicide does not carry any restrictions because it is ranked as only moderately toxic by ingestion and only slightly toxic by inhalation or skin exposure. Dicamba, however, is rapidly absorbed into the bloodstream from the gastrointestinal tract. So if there are granules that have not been tilled into the dirt, a horse could ingest Dicamba unknowingly and suffer the consequences.
3. Overdrive — Like Dicamba, there are no grazing or haying restrictions for Overdrive. The safety data sheet advises users to avoid release into the environment, stating specifically for farmers not to discharge Overdrive into the soil or subsoil or water because it is not readily biodegradable.
4. ForeFront — Like Lorsban, ForeFront requires a 7-day grazing restriction after being applied. Hay fields that have been sprayed with Forefront can only be used on the farm where the product is applied. The manure and hay that comes in contact with ForeFront cannot be used as compost due to its toxicity. Once a pasture has been sprayed it cannot be entered for at least 48 hours. It is highly toxic to aquatic organisms as well, and all runoff into the water should be avoided at all costs.
5. Cimarron — This herbicide carries no grazing or haying restrictions. However, after application of Cimarron, the toxic plants may become more appetizing to horses and livestock. Because of this, the pasture must be left alone until the plants have had ample time to dry. A field sprayed with Cimarron cannot be entered for at least 48 hours afterward. Cimarron is highly toxic to aquatic life and runoff into groundwater must be avoided.
Safdar Khan, who has served as director of toxicology at the ASPCA Animal Poison Control Center, says that “When herbicides are used it can bring certain chemical changes in the plant, which for some reason can make it more attractive to the horse.” Which means that no matter what herbicide you use, a horse may be more inclined to consume the toxic plants. Alternatives to herbicides are always available. A farmer can pull weeds up by their roots and keep pastures mowed early in the season, but this can be a daunting task if a pasture is large enough for livestock. There may not be a “safe”, non-toxic” way to prevent weeds in a horse pasture. However, by knowing the risks of exposure to animals, farmers can choose the best alternatives for their land.
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