2,4-D Amine is labeled for speedwell in general and can be used on pasture. Per label, application under drought conditions often will give poor results. The lower recommended rates will be satisfactory on susceptible annual weeds. For perennial weeds and conditions such as the very dry areas of the Western states, where control is difficult, the higher recommended rates should be used. However, germander speedwell is a pretty specific plant that is usually used as a desirable groundcover. So while I don't think that this specific species is on any labels, you will only see speewell in general on labels. We recommend reaching out to manufacturer at 334-741-9393 OR 888-ALLIGARE for further assistance in using this product for germander speedwell. It is highly recommended one removes any plants by hand, ideally as soon as they appear, as they have a fibrous root system so anything that remains may regenerate.