In terms of disease control, some early drilled crops of spring barle
However, most of the later-sown crops still have to receive a final application.
Late-season disease control in spring barley is designed to control diseases such as rhynchosporium, net blotch and ramularia.
Disease control
The risk of infection with rhynchosporium, net blotch and mildew will largely be determined by the disease rating of each individual variety. However, in the case of ramularia, it is normally caused by stress in the crop.
While different varieties have differing levels of tolerance to ramularia, being able to predict which varieties are going to show signs of infection is very difficult.
For this reason, Teagasc is recommending that growers protect all barley crops from ramularia.
Trials at Oak Park indicate that the multi-site folpet (Arizona, Stavento, Mirror, etc.) has some activity on ramularia, and when it is used with the azole, e.g., prothioconazole (Proline), reasonably good control can be expected.
However, timing of the application is critical as the fungicides are preventive only.
The Oak Park work has also clearly shown that from flag leaf fully emerged to the awns peeping is the optimum timing for applying the final fungicide.
Waiting for the heads to come fully out and start flowering, 10-14 days later, can reduce yields by 0.3-0.4t/ha.
The rationale for going in early, rather than waiting for the head to come out, is that all the products that are available will only work preventively; they will not cure the problem, once it becomes visible.
Therefore, by applying a fungicide early, growers will be attempting to delay the infection from occurring for as long as possible.
Eventually, spring barley crops will become infected with ramularia. But by delaying that infection occurring, growers will see a yield benefit.
Second fungicide
The second fungicide at awns peeping or what has become called the ‘paintbrush stage’ will consist of the multi-site folpet (Arizona) 1.5L/ha plus [half rate triazole plus strob/SDHI mix].
Teagasc trials consistently show that 50% rates of any triazole plus SDHI/strobilurin mix are adequate to control diseases such as rhynchosporium and net blotch.
Teagasc’s Deirdre Doyle discussed the issue of ramularia control at this year’s National Tillage Conference.
She explained that barley crops must produce high numbers of productive tillers in order to maximise final yields.
“The tillers produced by the plant must be protected from disease,” she said.
“Where fungicide use is concerned, it’s important to come in at growth stage 31/32 to deliver protection for the lower leaves.
“This should be followed up with another application between growth stages 45 and 49, in order to protect the upper canopy.”