I own a construction business; however, I mostly do noxious weed control & tree removal for cattle ranches in recent years. Is 238900 the best business code/activity?

That code is fine. It doesn’t really affect your return. 

You should be able to type in 238190 if that was the business code you used last year.

The code is not all that important, but I would use the same code year after year unless your business service changes. 

The code is useful to determine the types of expenses that would be related to that type of work. 

@Drake1960 

I tried typing it in, but it would not accept the old code.  It is no longer in the code list on TurboTax.

If you cannot use the same code as last year, see the list of acceptable codes to use for a Schedule C business in the link below.  The code list is on pages 19 through 21 of the PDF document.

2024 Instructions for Schedule C

@Drake1960