Question

I’ve recently purchased a farm that possesses plenty of nutritious forage for my horses, but there are lots of weeds as well. When I can afford it, I will have the pastures renovated by an expert in pasture management. Until then I am trying to curb the proliferation of thistles growing on my acreage. Yesterday, I actually witnessed my aged mare munching merrily on a thistle. Do horses normally eat thistles, and is there any harm in allowing my mare to ingest them? What’s the best way to rein in their existence on my land until professional help arrives?

Answer

Horsemen can learn lots of interesting tidbits by simply observing horses. You’ve come across a worthy fact yourself: horses find the flowering heads of thistles flavorsome. Horses typically stumble upon thistles as they investigate their surroundings, rarely seeking them out as they might a patch of tasty clover. Interest in thistles wanes quickly, and few horses will spend considerable time devouring them if more succulent plants are available. The prickles and spines of thistles may deter some horses, but determined browsers, with their mobile lips, can pluck off the flowered head without getting so much as a prick from spiky plant structures.

For the most part, members of the thistle family—those with blue, pink, or purple flowers—are harmless and safe for horses to nibble. However, a few species of thistle are toxic to horses. The most widespread toxic thistle is the yellow star thistle, which is found in the western United States, especially California.

Thistles are a ubiquitous plant. Few farms in the United States are probably completely devoid of them. They are sometimes considered weeds because of their ability to spread quickly. Left unchecked, thistles can become quite abundant. Some stands of thistle become so thick that horses will refuse to walk through them because of their prickliness. The pasture specialist you plan to work with will become a valuable resource and will likely offer a sound line of defense for ridding your fields of thistles.

This individual should be able to explain safe herbicide options, which will mean less work for you in the future. Until then, it seems the only methods available for slowing the spread of thistles on your property involve manual labor. Eradication is simple though time-consuming.

With hands sheathed in heavy gloves, pull out individual plants. Young plants without extensive root systems will probably yield easily to a gentle pull or a quick yank, but mature thistle plants with sprawling roots might need to be dug out with a shovel or similar implement. Dispose of the plants away from any land that may be used for agricultural purposes.

Timely mowing can also help prevent further plants from becoming established. If plants are mowed before the flowering stage, seeds will not be cast, making a future generation impossible.

Keeping your acreage clear of thistles is also a goodwill act towards your neighbors. They will appreciate your efforts in keeping the thistle population to a minimum. Winds disperse thistle seeds far and wide, and winds know nothing of manmade boundaries such as property lines!