Lawn Rust Disease: Orange Powder on Grass Blades

title: "Lawn Rust Disease: Orange and Yellow Powder on Grass Blades"

A lawn turning orange in late summer, with grass blades coated in powdery orange-yellow dust that rubs off on shoes and clothing, is a familiar sight on Long Island in August and September. The cause is lawn rust — a group of fungal diseases that attack cool-season turfgrasses during the warm, humid stretch at the end of summer.

Lawn rust is rarely a serious threat to an established lawn. Per Rutgers NJAES, it is "most common on slow-growing turf" — the disease thrives when grass is growing slowly due to heat, drought, low nitrogen, or shade. A lawn that is actively growing fast enough is largely able to outgrow the infection.

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What causes lawn rust

Lawn rust is caused by several species of fungi in the genus Puccinia and related genera. Per Penn State Extension, the most common species in the Northeast:

Per Rutgers NJAES, perennial ryegrass and Kentucky bluegrass are the most susceptible turf species to rust. Fine fescues show moderate susceptibility. Turf-type tall fescue is relatively resistant.