Slow growth will bring on rust
Roughs primarily but almost any high cut turf that has slowed growth is susceptible to rust. Rust is favored by relatively warm autumn days with cool nights that produce heavy dew. With nearly 5,000 different species of rust, the likelihood of variation in rust pathogens on turf would be expected. On Kentucky bluegrass, stem rust is the most widespread. Crown rust is the most widespread on tall fescue and perennial ryegrass. Symptoms initially appear as light green specks on the leaf blade that within a week turn orangish-reddish color. The appearance of pustules (uredinal), which contain the spores that can continue to infect. Rust is most favorable on drought stressed slow growing turf. If rust is a problem, fall fertilization can slow disease progress along with watering.