Dear Linda,

Thank you for your question.  There are several alternatives to glyphosate (active ingredient in Roundup Weed & Grass Killer and many other brands), but first a reminder on why glyphosate use is so widespread.  

• Offers broad-spectrum (i.e., nonselective), systemic activity (ability to move within the plant) reducing the need for retreatment
• Is less mobile in the environment than other herbicides available
• Allows for planting sensitive species after the treatment dries
• Has low acute toxicity

None of the following alternative active ingredients offer all of glyphosate's characteristics.

• Glufosinate (sounds similar, acts very differently)- The main difference here is that it only has contact activity, so it will only harm plant tissue that is contacted. It is not a good choice for perennial weeds that have extensive root systems/carbohydrate reserves. It can be a good choice for small annual weeds that are not yet flowering.
• Ammonium nonanoate- Similar to glufosinate as it only has contact activity. It is sometimes offered as an organic alternative because it can be naturally derived.
• Ammoniated soap of fatty acids- Similar comments as ammonium nonanoate.
• Acetic acid (aka vinegar)- Similar to those above as far as activity and useful scenarios. Has the potential risk of lowering soil pH with repeated use, possibly influencing future plant communities.      

 Attached are articles on alternatives to glyphosate.  I hope you will find them helpful.

Are There Alternatives to Glyphosate for Weed Control in Landscapes? | NC State Extension Publications (ncsu.edu)

Glyphosate (Roundup) Information and Alternatives for Weed Management | University of Maryland Extension (umd.edu)