Factors influencing successful disease management

Preventing cereal diseases begins with soil health. Focus on maintaining optimum pH levels with lime applications and ensure balanced nutrition. Take care to avoid applying too much nitrogen as this creates the conditions for diseases like powdery mildew to thrive. 

Getting out in your fields early and often can help you identify diseases before they have a severe impact. It also allows you to build up a picture of what’s happening on-farm so you can proactively manage disease in the coming season.

Planting resistant crop varieties can help reduce the risk of yield loss from cereal diseases. You can also plant varieties which mature at different times. For example, Fusarium disease in wheat is most prevalent in warm, humid conditions. If you plant varieties that flower at different times, it can help to spread the risk and mitigate yield loss. 

Crop rotation can help reduce disease carryover into the next growing season. Changing the type of crop you plant in a field can disrupt the cycle of cereal diseases which are specific to certain types of crop.

Weeds are well known hosts to cereal diseases, and they also compete with cereal crops for water, sunlight, and essential nutrients. Effective weed management using cultural control and herbicides will help you protect your crop yield quality. 

Many cereal diseases such as yellow rust, brown rusts, and Septoria tritici can be managed with fungicide applications at the crop growth stage. For example, in wheat:

T1 application as early as the four-leaf stage can help control diseases like powdery mildew and protect against Septoria tritici. 

T2 application once the flag leaf has emerged can help protect the leaf against Septoria tritici. This is important as it is the main yield producing leaf. 

T3 application when the head has just fully emerged protects the head from Fusarium disease which causes significant reductions in grain quality. 

Yellow rust is a damaging wheat crop disease. It can occur in barley, but it is not as common as many varieties are resistant. Yield losses of as much as 40-50% can occur in wheat, but you can minimise the risk by planting resistant varieties and applying fungicide at the right time. 

Yellow rust symptoms:

• Rows of yellow/orange pustules on plant leaves which form bands as leaves get older

• Infected leaves die off in May/June

• In severe cases, the ears can become infected, and spores can form between the grain and glumes

• Later in the season, black spores appear among the pustules

Yellow rust control in wheat

• Planting resistant varieties can help however be sure to check for disease regularly, as new strains can always develop.

• Applying fungicide can be very effective for the control of yellow rust - an SDHI fungicide like ELATUS^® Era offers powerful protection against yellow rust.

• Resistance is not currently reported in any of the major chemistry classes within yellow rust, but maintaining normal resistance management principles remains the right thing to do.

• Avoiding late drilling can reduce disease pressure.

• Managing nitrogen applications as excessive levels in crops can encourage fungal disease.

Brown rust affects wheat and barley crops. Brown rust in wheat is most common in the South and East of the UK due to their milder summers. As it develops later in the summer than yellow rust, brown rust causes a considerable loss of green leaf area and therefore yield. In barley, brown rust can spread fast. Disease that occurs early in the season can considerably reduce final yield. 

Brown rust symptoms:

• Tiny pustules appear on crops which range in colour from orange to brown-these may be mistaken for yellow rust

• Brown rust pustules appear more random, occurring in stripes like yellow rust

• Symptoms most often affect the leaves, but they can be seen on stems, leaf sheaths, and ears in severe cases

• As leaves get older, a green ‘island’ forms around pustules

• Later in the season, thick darker spores appear

Brown rust control:

• Plant resistant varieties and monitor for disease throughout the season.

• Manage nitrogen applications to avoid excessive levels in crops.

Apply a fungicide to protect against disease or to control established disease in wheat, apply when symptoms are visible or at T2 or T3 where risk of disease is high. In barley, use fungicides to control disease. Consider a combination of an azole and SDHI such as MIRAVIS^® Plus and ELATUS^® Era. 

Ramularia leaf spot is becoming an increasingly important barley disease in the UK. Very difficult to identify, Ramularia is often mistaken for other cereal diseases. 

Ramularia symptoms:

• Symptoms of the disease rarely appear until after flowering, though they may appear earlier in stressed crops. Once they do, you’ll see them first on the upper leaves. Typical signs of the disease include:

• Small, reddish/brown rectangular lesions which may be surrounded by a yellow margin

• Rapid aging and death of leaves-black spots with visible spores appear on dead leaves 

Ramularia leaf spot control

Preventative fungicide applications at growth stages 39-45 tend to be most effective. Later applications, up to growth stage 59 can also work if you are growing malting barley crops. However, post-flowering applications won’t be effective once symptoms are visible on the upper leaves. 

Fusarium affects wheat, barley, and oat crops in the UK, causing poor establishment and reducing yields. However, the most common concern is that some species of the disease produce mycotoxins, chemicals produced by fungi which are toxic to humans and animals. 

Fusarium symptoms:

• Symptoms of Fusarium in cereal crops include:

• Seedling death and poor establishment

• Foot rot, particularly from the late stem extension stage

• Ear blight, causing bleached ears with visible orange/pink spores on spikelets

Fusarium control:

• Rotate crops to break the cycle of disease.

• Apply a fungicide to suppress the disease.

• Spread chaff and straw across your fields during harvest. This can soak up moisture and slow down Fusarium growth. 

• Plant resistant varieties.

Rhynchosporium is a damaging barley disease that occurs in the UK. Most prevalent in the South-West, West, and North of the UK due to the wetter climate, the disease can severely impact crop yield quality and cause significant yield losses. 

Rhynchosporium symptoms:

Spring crops sown from December-February and early sown winter crops are more at risk from the disease. Symptoms are often first visible at the base of the leaf. They then spread to the rest of the leaf, followed by the ears and grain. Look out for:

• Oval or irregular pale green-grey lesions which develop a dark brown margin over time

• Leaf yellowing and death 

• Symptoms developing rapidly after the flag leaf has emerged

Rhynchosporium control

Control of this yield-robbing barley disease involves:

• Growing resistant varieties.

• Avoiding saving seeds from infected crops.

• Managing nitrogen-excessive levels can create the ideal conditions for the disease to thrive.

• Applying a protectant fungicide, ideally a combination of an azole and SDHI fungicide like MIRAVIS^® Plus and ELATUS^® Era, can help with disease management. 

Net blotch is a prevalent disease of barley in the UK. It reduces crop quality, which is bad news for growers of malting barley, and can cause yield losses of between 10-40% if it’s not controlled. Most damage is caused when symptoms occur during the winter and continue into the spring as the crop develops. The disease affects both winter and spring barley, though are often more damaging to winter barley. 

Net blotch symptoms:

• This barley disease infects the crop via infected seed or crop waste. Symptoms include:

• Spots develop which are often mistaken for ramularia leaf spot. These turn into brown stripes or blotches which spread from the base of the leaves. The way to tell the difference is that unlike ramularia, lesions are not rectangular and occur throughout the season, not just post-flowering. 

• In severe cases, yellowing of the leaves can occur and dark brown flecks develop on the glumes and awns. 

Net blotch control: 

• Planting resistant varieties can help with disease management, though you should continue to monitor for disease throughout the season.

• Clearing crop debris from infected crops is important as it can harbour disease.

• Avoiding early sowing can reduce disease risk.

• Managing nitrogen to avoid excessive levels helps avoid creating the conditions for the disease to thrive.

• Using clean seed reduces the risk of infection.

• Applying a mixture of fungicides at the T1 and T2 timings can control net blotch and reduce the risk of fungicide resistance. 

Crown rust is a major cereal disease affecting oats in the UK. Infections caused by the pathogen Puccinia coronata have become increasingly common and can reduce yield by between 10-20%. 
As the disease needs warm conditions to thrive, it often occurs just before harvest. 

Crown rust symptoms:

• Symptoms most often occur in June or July in higher temperatures. Here’s what to look out for:

• Orange/brown pustules appear on the surface of leaves. These may look similar to brown rust

• Infection can also affect the leaf sheaths and oat panicle 

• Later in the season, black pustules appear

Crown rust control:

Controlling this prevalent cereal disease involves:

• Growing resistant crop varieties.

• Using a fungicide that’s effective against crown rust, like ELATUS^® Era.