Dollar spot

Clarireedia jacksonii

Small bleached spots the size of a coin scattered across the lawn, each blade banded with a straw lesion. Almost always a sign the lawn is hungry, not sick.

Fungus Disfiguring Spread by contactSpread in waterSpread on tools & hands Spreads to neighbors

What you'll see

Round bleached-straw spots four to six centimeters across, sunken slightly below the surrounding turf.
Spots running together into larger irregular patches if it goes on.
Individual blades with a straw-colored band across them, bounded top and bottom by a reddish-brown line.
White cobwebby mycelium in the dew at dawn, disappearing as the lawn dries.
A lawn that is otherwise pale and slow-growing, which is the real clue.

Why it happens

A fungus that lives in the thatch and moves blade to blade by contact, on mowers and on shoes. It is a disease of hungry turf above all — low nitrogen slows the grass so much that it cannot outgrow the small lesions, which is why the same lawn shrugs it off after a feed.

Warm days and cool nights with heavy dew, from late spring through autumn. Drought stress, thin soil, low fertility and long dew periods all favor it; overwatered turf does not, which sets it apart from brown patch.

Treating it

Feed with a light nitrogen application; on a garden lawn this alone usually clears it in a fortnight.
Water deeply and early in the morning to shorten the dew period rather than lengthen it.
Drag a hose or a light brush across the lawn at dawn to knock the dew off.
Mow regularly with a sharp blade and collect the clippings while spots are active.
Leave the fungicide alone on a garden lawn; the grass recovers from the crown once it is fed.

Keeping it away

Keep the lawn adequately and evenly fed through the season rather than starving it and then dosing it.
Water deeply and infrequently in the morning so the roots go down and the dew period is short.
Reduce thatch, which holds both the fungus and the moisture.
Overseed with improved cultivars, which vary a great deal in susceptibility.
Improve drainage and air movement in the corners of the lawn where it always starts.

Who gets it

Lawn grasses of all kinds, worst on bentgrass, fine fescue and Bermudagrass.