I haven't done lawn care in an area that has a problem with sandburs but here's an article that might help.

Controlling Sandburs

Thanks for the article, it was a big help!!

Your welcome.

Here is another excerpt I stumbled across that is from KU, and I thought of this thread. It mentions both of the products noted in the article from Texas. Might be of additional help.

Hot, dry years often lead to problems with grassy
sandbur. Mature plants are difficult to control with
products that won't hurt the lawn. Glyphosate
(Roundup) works well but kills whatever it hits.
The best control for grassy sandbur is to use a
preemergence herbicide in the spring before the
plant comes up. However, not all preemergence
herbicides are effective. The two products that are
effective are oryzalin and pendimethalin.
Oryzalin is sold under the trade names of Surflan
and Weed Impede. It can be used on all
warm-season grasses as well as tall fescue. It should not be used on cool-season grasses other
than tall fescue such as Kentucky bluegrass. Apply oryzalin about April 15 when redbud trees
approach full bloom.
Pendimethalin is sold commercially as Pendulum as well as several other names. On the
homeowner side, it is sold as Scotts Halts. Pendimethalin is best applied as a split application
with the first half applied about April 15 and the second about June 1. Alternatively, make the
first application when redbud trees approach full bloom and the second six weeks later.