Question
didn't have the time this year to take care of the lawn. Need help to correct the probelms. Glover, crap grass is everywhere. Both neighbors lawn are neglected. In just one season they invaded my lawn.
What should I apply this Fall to take care of this matter? Appreciate any infomation you can give me.
Always had a nice lawn. Thanks....

Answer
Good afternoon Joyce:

Crabgrass can be treated through both chemical and nonchemical methods. Proper lawn care practices to encourage a dense stand of vigorous grass are the best way to prevent crabgrass from invading your lawn. Mowing height can have a big impact; lawns mowed higher (over 2 inches) tend to have less problems with crabgrass. Close-mowed lawns tend to open up, allowing crabgrass to invade. Light, frequent watering also favors crabgrass. Crabgrass often invades areas seeded in late spring because of bare soil, frequent watering, and onset of hot weather, ideal for its growth.
Preemergence herbicides prevent annual crabgrass from emerging. Timing of application is very important, as the weed killer should be applied before the crabgrass emerges from the soil. Crabgrass will germinate when soil temperatures are greater than 55 to 60 degrees F for 7-10 consecutive days, and continues until soils reach 95 degrees F. Other annual grasses germinate as soils get warmer than 60 degrees.
Late April to early May is the suggested time for applying a preemergence crabgrass herbicide. If the spring is very warm, consider late April. In cold, "late" springs, these materials could be put down well into May. Crabgrass prevention and spring fertilization can be done at the same time. Preemergence herbicides include benefin, benefin/trifluralin, bensulide, dithiopyr, oxzdiazon, pendimethalin, prodiamine, and siduron.  If you plan on reseeding in the spring at the same time you use the preemergence make sure you use siduron as this will not kill the new grass seedlings.
The suggested strategy to avoid crabgrass next season would be to improve the lawn through cultural practices and consider a preemergence herbicide in spring.

There are a number of broadleaf weed herbicides (weed killers) available for use on lawns to control clover. Only apply to actively growing weeds. Choices found in garden centers typically include 2,4-D (2,4-dichlorophenoxyacetic acid); mecoprop or MCPP (2-(2-methyl-4-chlorophenoxy) propionic acid); or dicamba (3,6-dichloro-o-anisic acid); with two and three-way combinations available.
Thoroughly read, understand, and follow all information on herbicide labels. There are general guidelines for using broadleaf herbicides on lawns. Avoid windy days, as these materials can damage many landscape and garden plants if they drift (spray droplets land off the lawn). Also avoid hot days (over 85 degrees F). It's best to have adequate soil moisture, but no rain for 24 hours after application. Don't mow for few days before and after application. Consider spot treating weeds rather than broadcasting weed killer over the entire area. Use caution on newly seeded areas; wait 4 mowings before treating a newly seeded lawn and wait 30 days before seeding an area treated with broadleaf herbicides. Refer to the label regarding any potential hazards when used on lawns over the root zone of trees (such as with dicamba).
Early to mid fall can be a good time to control perennial broadleaf weeds, such as clover. Control may be good as weeds prepare for winter dormancy and lawns fill-in bare areas created by the weed dying readily in the cooler weather of fall. Spring and early summer applications may not provide as good of control as fall. In addition, warmer temperatures increase the chance of lawn injury. Regardless the time of the year, weeds need to be actively growing for herbicides to work.

My suggestion would be to begin late in September using broadleaf herbicides to eliminate the clover. If you can spot treat that would be better and more economical. In late October begin to overseed the lawn in the bare areas. Wait until Spring to begin using a preemergence crabgrass killer as indicated above.

I hope I have helped you. Good luck,
"Mac McMahon