Spring barley crops are demonstrating tremendous potential to produce excellent yields over the coming months.
But putting in place an effective disease control programme is critically important in order to ensure that all of this potential is fully realised.
Late season disease control in spring barley is designed to control diseases such as rhynchosporium, net blotch and ramularia. Mildew has not been much of an issue in recent years.
The risk of infection of rhynchosporium or net blotch 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.
Disease control in spring barley
For this reason, Teagasc recommends that growers protect all barley crops from ramularia. Trials at Oak Park indicate that the multi-site folpet (Arizona, Stavento, Mirror) has some activity on ramularia and when it is used with an azole, e.g., prothioconazole (Proline, etc.), we can expect reasonably good control.
However, timing of the application is critical as the fungicides are preventative only. Again, Teagasc trials have shown that from flag leaf fully emerged to the awns peeping is the optimum timing for applying the final fungicide.
However, waiting for the heads to come fully out and start flowering, i.e., 10-14 days later, can reduce yields by 0.3- 0.4t/ha.
Barley crops that have received their first fungicide at late tillering should have good coverage for about three weeks, especially if an azole plus strob/SDHI mix was applied.
Some crops were sprayed a little later due to spraying conditions being tricky in mid-May.
Growers should avoid the temptation to delay the second fungicide application until the three weeks are up, as this could result in the incorrect timing for that second fungicide.
The second fungicide at awns peeping or what has been called the ‘paintbrush stage’ will consist of the multi-site folpet (Arizona) 1.5L/ha plus a half rate azole plus strob/SDHI mix.
Various options are available, but once the basic components are in the mix (folpet plus azole plus strob/SDHI), growers should expect good control of diseases.
Teagasc trials show that 50% rates of any azole plus an SDHI/strob mix are adequate to control diseases such as rhynchosporium and net blotch.