In a post titled "Rude message to Donald Trump appears as a crop circle on Stoke Mandeville farm," The Bucks Herald newspaper of Buckinghamshire, England reports,
The message has rather a naughty word in Russian (F**K), followed by Trump. Speaking to the farm owner, the crop circle has been manufactured as part of an art installation. It appears on the flight path that Donald Trump will take from London to Chequers this Thursday. ... The owner of Moat Farm in Stoke Mandeville said: "I was approached by an artist, who wished to remain anonymous to use one of my crop fields."
That story was published on Tuesday. But on Thursday, The Tenth Man, a branding and content agency with offices in London and Dublin, stepped forward to take credit, posting the above video on its YouTube channel. It turns out the actual creator of the work isn't "an artist" per se, but a British company, Circlemakers, that specializes in such stunts.
If you want to know how to pronounce the first word carved into the field, click one of the brief audio clips for it at Forvo ("All the words in the world. Pronounced"). And, courtesy of the "Russian Swear Words" section of The Russian Blog, more context on the word:
"Whore." That's the basic translation of this word, but it may also mean "bitch, slut, prostitute, or a promiscuous person." It is considered to be a general-purpose insult to anyone, so it may be used with both women and men. It may also be used as an exclamation, in which it can mean "fuck!", "shit!", or "damn (it)!" It can also be used as an intensive particle to add the meaning "fucking", "damn", etc.