Foliar diseases can significantly reduce hay and milling oat yield and quality. The major foliar diseases of oats in Victoria include Red leather leaf, Bacterial blight, Septoria blotch, Crown (Leaf) rust and Stem rust. Recent surveillance activities in Victoria (2018-2021) identified Red  leather leaf and Bacterial blight as the most common foliar diseases with other diseases such as Stem rust, Crown rust and Septoria blotch observed at low incidence.

Crops grown in the high and medium rainfall zones generally had higher disease severity compared to crops grown in low rainfall zones. In this chapter we describe the identification and management of these important foliar diseases affecting oats.

Overview of symptoms and the optimal temperature range for oat foliar diseases

Disease	Pathogen	Symptoms	Optimal Temperature Range for Infection (°C)
Red leather leaf	Neospermospora avenae	Leathery textured reddish brown irregular shaped lesions on leaves	5-16
Stripe blight	Pseudomonas syringae pv. striafaciens	Reddish-brown stripes with yellow and red margins on leaves	Unknown
Halo blight	Pseudomonas syringae pv. coronafaciens	Yellow-brown oval shaped water-soaked spots with yellow-green halo on leaves	Unknown
Crown rust (leaf rust)	Puccinia coronata var. avenae	Small round to oblong, orange to yellow-coloured pustules on leaves, leaf sheaths and heads	15-22
Stem rust	Puccinia graminis var. avenae	Reddish-brown, powdery, oblong pustules with a characteristic torn margin on both sides of the leaves, on the stems and the glumes	18-30