Spurge and rust
First the spurge. I assume that you are talking about either of these two plants called Spotted or Creeping Spurge.http://www.ipm.ucdavis.edu/PMG/WEEDS/creeping_spurge.html OR http://www.ipm.ucdavis.edu/PMG/WEEDS/spotted_spurge.html
IF so, then your control strategy hinges on the fact that these two spurges are summer annuals. Summer annuals grow from seed in the spring and die in the same year after producing flowers and seed. Your best bet is going to be to treat your lawn with a spring time preemergent weed killer that will inhibit the germination of these weed seeds.
Rust: This is a fungal problem that begins as as small yellow spots on leaves and stems that form elongated, reddish brown or orange pustules. This disease will kill leaves and it can debilitate plants when it is severe. The turfgrass quality is reduced because of poor color and reduced plant vigor. Rust is contagious from other plants and can survive and over winter in infected turf types that include Bluegrasses, ryegrasses, zoysiagrass, and tall fescue.
Control will require you to do the following:
Avoid overhead watering in temperatures (70-72 deg) that favor prolonged leaf wetness of 10-12 hours.
Irrigation in the morning and provide good air movement across the lawn- remove low hanging tree branches, raise foliage that blocks the breeze..
Make sure that your turf is in good health with adequate nutrients for optimal growth- especially Nitrogen. Optimal fertilizer regimens for your turf type will depend on what type of grass you have and on your results of soil testing.
Do not overapply N fertilizer
Mow regularly and remove clippings to remove infected blades and spores of the fungus.
Choose rust resistant varieties of grass and for best results have a mixed turf with different kinds of grass species in it.