Tan Spot

Stripe rust (Puccinia striiformis) also known as yellow rust, is a common disease of wheat which can result in significant yield loss if not controlled. Stripe rust is favoured by cooler, moist conditions with the initial source of inoculum being infected volunteer cereals. Under favourable conditions stripe rust can develop very quickly forming disease foci surrounding the initial infection source. At first spores tend to be scattered on the leaf but on more mature leaves they show the typical stripe arrangement which gives the fungus its common name. Occasionally stripe rust can infect the ear.

Powdery mildew is a common parasitic fungus of wheat. Powdery mildew produces white, fluffy mycelial growth, usually on the leaves but also on the stems and ears and as the disease only infects the outer plant layers it can be scraped off quite easily. Powdery mildew needs to infect living plant material to survive and so wind borne spores from volunteer plants are the likely source of inoculum. Serious disease infections can lead to significant yield losses.

Ear disease complex is a term used to describe a range of weak pathogens that attack the ear, predominately of wheat, causing the ear to turn black. Due to the black colouration these fungi are often referred to as sooty moulds. While overall these fungi do not lead to high yield losses they do produce an unsightly crop and they can reduce grain quality. The problem tends to be worse in wet summers and when harvest is delayed.

Previously referred to as Septoria nodorum and typically referred to as glume blotch (Parastgonospora nodorum) because it is normally seen on wheat ears, the disease can infect wheat foliage when it is called leaf blotch Leaf blotch can be identified from Zymoseptoria tritici by the lack of black pycnidia and the more oval appearance of the lesions. Glume blotch can be a problem in wet seasons and tends to give the ears a purple-brown appearance.

Speckled leaf blotch (also known as septoria tritici and septoria leaf blotch) has recently become a common disease of wheat which can result in significant yield loss if not controlled. The main source of infection is spores from infected crop debris with first infections taking place from March to May. Following infection the fungus develops within the leaf until sporulating lesions appear. The key identification feature during winter is the presence of black pycnidia. Later in the year the lesions also tend to become stripe like. The disease undergoes multiple cycles within a crop.