If your grass develops disease, clean and sterilize your mower blades before you mow again. If you do not, you risk spreading the disease over your entire lawn, or, if you've treated for the disease, you risk reinfection. Sterilizing mower blades is not any more difficult than sterilizing other metal stools or surfaces. It takes just a few extra minutes after cleaning the blades.
Put on rubber gloves and mix 1 tbsp. of dish detergent in a 1-gallon bucket of warm water.
Lay the mower on its side so you can access the blades. This is best done on a cement patio or driveway, so you avoid getting infected grass clippings or dirt on your lawn.
Remove clumps of dirt and grass by hand (and dispose of these in a plastic bag, away from your lawn). Well-maintained mower blades are sharp, so take your time doing this so you do not cut yourself.
Wet a nylon scrubbing sponge in your bucket of water and detergent and scrub the mower blades until you've removed the dirt and debris.
Rinse the blades with a garden hose. Dry the mower blades with a towel.
Dump out your soapy water in a sink and rinse the container. Add one part household bleach to nine parts water to the container. This solution will disinfect mower blades, as suggested by Pnwmg.org (see Reference 1).
Dip a cloth in the bleach-and-water solution. Wipe this over the blades. Allow it to dry (do not rinse).