Crop Clinic

The UKCPVS survey monitors changes in the cereal diseases which may have implications for break downs in variety resistance to major cereal diseases including yellow rust in wheat and powdery mildew in barley.

Most cereal diseases are specific to each crop. Most wheat diseases for example, will not attack barley or oats and vice versa. Diseases will however spread from winter cereals onto spring cereals of the same type.

Although varieties show differences in resistance to diseases, the fungi which cause disease are constantly changing and finding ways to break down the resistance. This survey monitors these changes and the information can give  plant breeders and growers early warnings in the likely breakdown in varietal resistance, or provide assurance that varietal resistance is still effective.

Wheat diseases

Yellow rust

The yellow rust race,  commonly known as the Oxbow race is now widespread. A new race which attacks Solstice was widespread in 2009. This race can overcome the resistance of Viscount, QPlus and Humber. 

An isolate which showed virulence for Claire at the seedling stage failed to infect adult plants of the variety
Brown rust

There were indications that Oakley, Scout and Viscount are susceptible to the Robigus-virulent isolates of brown rust.

Virulence to Robigus was detected in less than 20% of isolates.

Only two commercial varieties Timber and Cassius were resistant to all isolates.

Mildew

Most varieties have good resistance to mildew, but the varieties Claire and Option are susceptible and this should be taken into account when choosing varieties for mildew prone areas. Robigus is now susceptible to mildew and it as also been found on some crops of Alchemy.

Barley diseases

Mildew

The mlo resistance remains effective and is used in many spring barley varieties.

Virlulence is common for most of the other resistances found in current UK barley varieties. 

Rhynchosporium

Spring barley varieties are mostly susceptible to rhynchosporium. Although the resistance rating for winter barley crops are generally high, in high risk areas of the UK, varieties with ratings of 6, 7 and 8 can be badly affected.

Brown rust

Brown rust was widespread in winter barley in 2007. This may be a consequence of an exceptionally warm April, but the samples collected in 2006 carry complex combinations of virulence factors.

 

Yellow rust

Reports of yellow rust were more frequent in 2002, 2004 and 2005. None were reported in 2006. The majority of samples were received from Northumberland and Cambrige. Winter varieties most susceptible to yellow rust on the 2006 Recommended List  include Colossus (3) and Amarena (3). Spring varieties include: NFC Tipple (3), Cocktail (3), Tocada (3), Doyen (3) Rebecca (3). The number in  brackets refers to the resistance rating for yellow rust.

 
Oat diseases

Crown rust

The winter variety Millennium is becoming more susceptible to crown rust.

Acknowledgements

The Survey is  sponsored by HGCA and FERA. Full details of the survey are available on the HGCA web site.