Yellow grass can prove frustrating to homeowners trying to maintain a lush, green lawn. Many turf problems point to a single, distinct culprit, but several conditions cause grass to take on a yellow tinge, including fungi, pests, a lack of nutrients and certain environmental conditions. Dealing with yellow grass in turf areas is a twofold problem: homeowners must examine the grass and the area to identify the cause of the yellowing, and then take steps to correct it.
Perform special maintenance tasks on the grass if it is yellowing because it is in a predominately shaded area. Grow the turf 1 inch higher than the rest of the grass, water it whenever it appears dry and treat it with half the amount of fertiliser you use in sunny, normal areas. Prune trees and bushes to allow the grass to receive as much sun as possible.
Test the soil to determine if the turf is infested with pests. Add 2 tbsp of liquid detergent to 2 gallons of water, pour it over 3 square feet of the affected lawn, and watch for bugs to surface. Pull up the yellow grass in another area and dig two inches into the dirt to look for grubs, which look like fat, white worms. Apply an insecticide appropriate for the particular pest if any are residing in the lawn. Bring one of the insects to a local cooperative extension office if you need help identifying it.
Add nutrients to the turf if the grass appears uniformly yellow. Apply a nitrogen-rich fertiliser to the turf if the grass grows in patches and the strands appear thin as well as yellow. If the lawn is already fertilised regularly, the University of Florida IFAS Extension suggests applying a granular nitrogen-and-phosphorus-free nutrient blend containing iron, manganese, magnesium and potassium to the yellow turf.
Examine the yellow grass more thoroughly if it occurs in patches but is not a result of pest infestation. Ignore 6-to-12-inch yellow rings appearing during the cooler seasons of spring and fall, which is caused by a fungus known as yellow patch. Yellow patch clears up in warmer weather. Send soil and grass samples from any otherwise unidentifiable yellow patches of turf to your local cooperative university lab for testing.
Consult with a lawn care professional or cooperative extension staff if identifying and correcting the yellow patches proves frustrating.