Disease pressure is high in wheat crops, with yellow rust and septoria already being seen, plus warnings of a higher eyespot risk.
To help you identify these diseases, Farmers Weekly has teamed up with the HGCA to produce this guide.
This is the most damaging foliar disease of wheat in the UK and can lead to yield losses, worth about £250/ha based on a grain price of £150/t and an average treated yield of 8.5t/ha.
Symptoms: During winter, brown oval lesions with small black fruiting bodies (pycnidia) can be found on older leaves. Moving into spring, lesions tend to be rectangular and confined by leaf veins. These lesions are often surrounded by areas of yellowing or leaf death.
Crops affected: While septoria tritici mainly affects wheat, the disease is also seen on rye.
Can be confused with: Symptoms do not appear immediately on a new leaf and only appear in the last third of its lifecycle, so can appear disease-free.
If left untreated, yellow rust can cause yield losses of up to 50%, but well-timed fungicide treatment usually keeps losses down.
Symptoms: In late winter and spring, small patches of yellow pustules show the disease is present. From this stage, the disease can spread rapidly so it is important to control it promptly. As the disease develops, pustules form distinctive yellow stripes between the leaf veins.
Crops affected: Wheat, barley and triticale are all affected by yellow rust. Different forms of the fungus (Puccinia striiformis) attack different crops so you do not normally get cross-infection. Also, for each crop, there are different races that mainly attack specific varieties.
Can be confused with: Early on, the yellow-to-orange-coloured pustules can be confused with brown rust, until they form the stripes.
There is a large seasonal and geographic variation in brown rust severity and it is more common in southern and eastern England. In 2007, a particularly bad year, losses were estimated at £11.2m.
Symptoms: In winter, individual orange-brown pustules can be found on older leaves. Later in the season, pustules can cover leaves in a random pattern. The infection can also affect the glumes and the stem.
Crops affected: Specific types of brown rust attack wheat, barley, rye and triticale, but they do not cross-infect. Like yellow rust, there are specific races that are particularly virulent against specific varieties.
Can be confused with: Early in the season, the pustules may be confused with yellow rust. The key difference is that brown rust appears in a scattered, random pattern and not in stripes like yellow rust.
This disease affects nutrient and water uptake, which in turn affects yield and quality. It can also cause lodging in weakened stems, with severe cases reducing yield by up to 30%.
Symptoms: Eyespot affects the stem base of cereals. The first visible symptom is a brown smudge on the leaf sheath at the stem base. In early-sown crops, lesions may penetrate one or two leaf sheaths. Later in the season, the symptoms are more distinct, with a large eye-shaped lesion just below the first node.
Crops affected: Eyespot can affect all cereal crops commonly grown in the UK.
Can be confused with: The early symptoms of eyespot can be confused with sharp eyespot and fusarium spp. However, these diseases usually only affect the outer leaf sheath, making it easier to tell them apart as the season progresses.
(Source – http://www.fwi.co.uk/articles/06/03/2014/143628/top-tips-on-identifying-four-key-wheat-diseases.htm)