Dollar Spot
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Watch it before you act
At this level the damage rarely costs the crop. Note the date, check twice a week, and act only if it reaches new growth or the weather turns favourable for it.
Rain and irrigation splash
Water splashing off soil and infected leaves carries it upward and along the row. Watering at the base and mulching the soil surface break the route.
It carries over to next season in soil, debris or seed — which is why rotation matters here, not just treatment.
Hot compost only
A heap that reaches and holds 55–65°C throughout will destroy it. A cool corner heap will not, and will return the problem to the beds with the finished compost.
When and where to look
Scout the planting while temperatures hold between 15°C and 30°C, with humidity above 85%, after rain or heavy dew, while the leaves are still wet. Risk builds after roughly 10 unbroken hours of those conditions, so the morning after such a night is the moment to look.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Dollar spot (Clarireedia species) shows up on closely mown turf during warm days followed by heavy dew and cool nights. Like red thread it is strongly associated with low nitrogen and a dry root zone under a wet surface.
Symptoms
Small, sharply defined straw-coloured spots the size of a coin, which can merge into larger sunken areas. Individual blades carry a bleached lesion with a distinct reddish-brown border across the leaf.
Organic Treatment
Apply a light nitrogen feed and water deeply but infrequently so the root zone is moist while the surface dries. Switch irrigation to early morning and drag a hose or brush across the lawn to knock dew off.
Chemical Treatment
Systemic turf fungicides control it, but resistance builds quickly where they are used routinely. Reserve them for high-value turf and always alternate active ingredients.
Prevention
Keep nitrogen adequate through summer, raise the mowing height in hot weather, remove dew in the morning, and reduce thatch by scarifying so the canopy dries faster.
Crops at risk
Related problems
Dollar Spot risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.