Turf Rust Disease

(Causal fungi: Puccinia spp.)

Rust diseases are foliar issues affecting turfgrasses commonly found on golf courses, athletic fields, home lawns, parks, and institutional grounds. These diseases are caused by fungi of the Puccinia genus. Some common types include stem, stripe, crown, and leaf rust.

Symptoms and Signs #

• Initial Symptoms: Pale-yellow speckling of leaves or stems.
• Progression: Yellow areas grow larger and align with leaf veins. Eventually, the leaf surface ruptures, forming reddish-brown spore masses (uredinia), also called pustules.
• Advanced Symptoms: Heavily infected plants resemble rusty iron, and an orange powder collects on shoes or fingers upon contact.
• Timing: Rust diseases typically appear in late summer or early fall.

Disease Cycle #

• Rust diseases have a complex developmental cycle, with five distinct spore production stages in most species. Some stages occur on non-turfgrass plants, like woody shrubs or ornamental plants.
• Rust diseases rarely kill turfgrasses but weaken them, increasing susceptibility to stressors like drought and heat.

Cultural Control #

• Nitrogen Management: Ensure adequate nitrogen levels to support turf growth in late summer.
• Irrigation: Maintain proper watering to minimize stress.
• Resistant Cultivars: Select rust-resistant cultivars of perennial ryegrass and Kentucky bluegrass when possible.
• Maintenance Practices: Follow proper mowing and maintenance practices to reduce susceptibility.

Chemical Control #

Fungicides are rarely needed for rust diseases but may be applied in high-visibility areas or to newly seeded turf showing symptoms. Some recommended fungicides include:

Demethylation Inhibitors (DMI) #

• Flutriafol: Found in Rayora.
• Metconazole: Found in Tourney.
• Myclobutanil: Examples include Eagle 20EW.
• Propiconazole: Examples include Banner Maxx II.
• Tebuconazole: Examples include Mirage Stressgard.
• Triadimefon: Found in Bayleton FLO.

Methyl Benzimidazole Carbamates (MBC) #

• Thiophanate-methyl: Found in products like 3336 DG and TM 4.5.

Quinone Outside Inhibitors (QoI) #

• Azoxystrobin: Examples include Heritage TL.
• Fluoxastrobin: Found in Disarm G.
• Mandestrobin: Found in Pinpoint.

Succinate Dehydrogenase Inhibitors (SDHI) #

• Penthiopyrad: Found in Velista.

Combination Fungicides #

Some products combine multiple active ingredients for improved control:

• Heritage Action (Azoxystrobin + Acibenzolar-S-methyl)
• Headway G (Azoxystrobin + Propiconazole)
• Lexicon Intrinsic (Pyraclostrobin + Fluxapyroxad)