Question
I live in Utah and have spots in my grass that are turning limegreen.  I saw a previous question like this that was asked and you said it was lack of iron.  I had 2 spots like this last year and both spots died.  I put down iron this year and now I have lime green in many spots in my yard.  I dont want to wait for it to die.  What can I do?  Could it be sod webworm?  What else could it be?

Answer
Hi Greg;
I have not had sod webworm, so I don't know what the damage looks like.
I looked up sod webworms, and that doesn't mention the grass turning lime green, just turning brown.
Tis is how it says to check for sod webworms.
In spring,,,

There are several species of caterpillars called sod webworms that can be highly destructive pests of Ohio lawns. They may also become important pests of grass covered parks, cemeteries, golf courses. They have even been noted to cause damage in small grain crops such as corn, wheat and oats. Damage to grass is caused by the feeding of the larval or "worm" stage. The adult moth does not cause damage to turf, other plants or clothing.

The damage caused by sod webworms may first appear in early spring. The damage shows up as small dead patches of grass among the normally growing grass. The summer generation may cause general turf thinning or even irregular dead patches in late June into early August. Sod webworms prefer sunny areas and the larvae are often found on south facing, steep slopes and banks, where it is hot and dry. Heavily shaded turf is seldom attacked by the larvae.

The most severe damage usually shows up in July into early August. Sod webworms prefer sunny areas and the larvae are often found on south facing, steep slopes and banks, where it is hot and dry. Heavily shaded turf is seldom attacked by the larvae.
The most severe damage usually shows up in July and August when the temperature is hot and the grass is not growing vigorously. In fact, most sod webworm damage is mistaken for heat and drought stress. Sod webworm-damaged lawns may recover slowly.
These thin turf areas allow weeds to establish in the lawn making it unsightly.

The general thinning of turf is usually not associated with sod webworm activity, and thus, goes undiagnosed. The sod webworm caterpillars live in tunnels constructed in turf thatch or extending to the soil under the turf. These tunnels are silk lined and the webbing joins soil particles and leaves together. The larvae emerge from these burrows to chew grass blades off just above the thatch line, usually at night.
In thick, green turf, injury appears as small brown patches about the size of a quarter to three inches in diameter. When many larvae are present in mid-summer, the small brown patches run together and form large irregular, thin and brown areas.

Confirming Sod Webworm Activity
The surest way to tell if you have sod webworms is to find a suspected area of infestation (brown patches). Get down on your hands and knees, take your two index fingers and part the grass blades in the area between dead and live grass and look for an area with small green pellets. The pellets, called frass, are the excrement of the larvae and indicate that a larva is close by. Sod webworm adults are about 3/4-inch long, cigar-shaped and buff-colored moths. They typically roll their wings around the body when resting on a grass blade. Two small snout-like projections are visible at the front of the head.

When the grass dies, can you easily pull up some of it, and feel a moist slimy feel?
You may have a fungus.
Good treatments for fungus are. corn gluten, agricultural corm meal, or baking soda disolved in water.
I use baking soda. I disolve 1/4th cup soda to 1 gallon of water, and spray to drench the area thoroughly.
there are other nutrients that when they are lacking, will turn the plant life light green, but a feeding should take care of that.
I am going to post this on the furum on the organic site I belong to, and should have some more answers in a few days.
I am having trouble with my email, so i may not get an answer when they send it, so if you don't hear from me in 3 or 4 days, write me, and I will check in there again.
In the meantime,. if you spray with the baking soda in water, or use corn gluten or agricultural cornmeal, it may stop it, and it cretainly won't do any damage to your lawn.
Charlotte