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With T0 approaching, watch out for disease

Agronomy Issues
Yellow rust spores

Although we have recently had frost, ice and a fair amount of snow in many areas, disease has been present over winter, with mildew found on many winter barley and wheat varieties.  The cold snap might have cleared up some disease, but rust is still lurking and as the weather starts to get better, it will rear its ugly head again!  Even in 2018, where the “beast from the east” helped reduce early season yellow rust infections, yield responses of 0.4T/ha were seen from T0 applications on susceptible varieties.

A number of sightings of yellow rust have been reported so far this year, though very little has been seen on our Innovation Centres across the UK. 

"Only 5 winter wheat varieties on the AHDB Recommended List are resistant to yellow rust at the seedling stage, therefore regular checks before the T0 application are advisable to map the progression of rust in different varieties"

Kathryn Hamlen, Technical Manager Conventional Cereals

GRAHAM has an 8 rating for Yellow Rust, and both SHABRAS and GLEAM have 7 ratings, however we often see the disease on these varieties in the autumn.  Many varieties with high resistance rating for yellow rust will show symptoms at the seedling stage before they reach stem extension.  Adult plant resistance will kick in later and this is the rating seen on the AHDB Recommended List.

Septoria tritici can also be found in low levels across winter wheat varieties at this stage in the year.  The key to controlling this disease effectively is getting on top of it early, especially as the available curative activity is somewhat limited.  Factors affecting disease include early drilling and variety choice as well as weather patterns later in the year. 

At the T0 timing, the advice is to base the program on Septoria tritici management, starting with Chlorothalanil products such as BRAVO. If rust is deemed a risk, apply a rust active triazole such as CHEROKEE or ALTO ELITE if rust is active; if rust is not active, but the variety has a low rating, AMISTAR OPTI can be used.

GRAHAM is now well established as a ‘cleaner variety’ with a high Septoria tritici resistance rating of 6.9.  There are some exciting new varieties recommended this year with very high Septoria resistance, however, even on these varieties we are seeing a moderate level of disease on our Platform Sites this autumn.  In order to maintain the canopy to maximise yield, a fungicide program will still be required, although this should be adapted to the disease pressure on the crop, as the varietal resistance will become apparent later on in the season. 

Both GLEAM and SHABRAS perform very well as a second cereal in the rotation, GLEAM has the highest yield as a second cereal out of all the winter wheats on the Recommended List.  Second wheats have a higher risk of take all, so in areas with a history of this disease the effects can be mitigated with an application of AMISTAR or AMISAR OPTI.

It is clear that both variety and location will make a huge difference in the types and levels of disease found in each crop, which is why an adaptive approach to disease management is key to protecting yield.

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