Greetings LaVern:
Dow's Remedy Ultra (a.i., triclopyr ester) is labeled for treating Osage-orange. Anytime of year will work for this herbicide as it can be used as a foliar spray, cut stump treatment, or basal bark treatment.
Remedy Ultra: For the control of woody plants and broadleaf weeds on rangeland, permanent grass pastures, and conservation reserve program (CRP) acres (including fence rows and non-irrigation ditch banks within these areas).
Best of luck and always follow the pesticide label -- it's the law!
