For an entirely descriptive mark (like 'fruit business' would almost certainly be) to be able to appear on the principal register, the USPTO would need to determine that 'fruit business' has come to have a meaning secondary to its regular, wholly-descriptive meaning. Thus, for 'fruit business' to appear on the primary register, the USPTO would need to find that 'fruit business' has come to be associated with this one particular company amongst a relatively substantial segment of the market. The USPTO would also need to find that 'fruit business' isn't generic (and a name like 'fruit business' is probably a pretty good bet to be a wholly generic term for a business dealing in fruits of various types.) Without a finding of these factors, the USPTO would relegate 'fruit business' to the supplemental register, where it gets basically no respect from the USPTO, and no real protection beyond what the common law would give.
It's also possible that 'fruit business' could also be incorporated into a logo containing non-generic design elements, but in that case, the fruit business with 'fruit business' in its logo would likely have to disclaim any right to the name 'fruit business' when used outside of its distinctive logo. Again, it seems like 'fruit business' would be the sort of mark that would be completely generic for a fruit business, and so would likely need to be disclaimed if 'fruit business' didn't want to deal with a long process of trying to prove secondary meaning and the likelihood of a denial at the end of the process.
And even if 'fruit business' were a mark on the principal register, it's entirely unlikely that they would be able to completely block any company operating on a similarly fruit-based model from using the term 'fruit', since after all, 'fruit' is a wholly generic term for... well, for fruit. So I would think that 'fruit services' or 'fruit market' would be able to use the word 'fruit' in their names, but would also need to expect similar obstacles to registration as a company like 'fruit business' would, since all those terms are so generic or descriptive -- I would expect any such business applying for registration to have to have their mark sit in the cheap seats of the supplemental register until there's simply no question that people have come to think of 'fruit services' as a very particular fruit services company (and all this assuming that the USPTO wouldn't just find 'fruit services' to be entirely too generic a name for a company which provides services to apples, pears, or even tomatoes and cayenne peppers.)
Due to these considerations, I would think that coming up with some sort of fanciful or suggestive name to tack onto your fruit services company, such as 'Perihelion fruit services', would greatly enhance the likelihood of your trademark being approved for registration, and you wouldn't have quite so many uncertainties regarding whether or not you would be able to ever get any trademark protection for your name (since it's not just a generic term for your type of business). Adopting some sort of fanciful or suggestive name for your fruit company would also tend to reduce the likelihood that the USPTO would decline your application due to your mark having a substantial likelihood of confusion with another mark.