31 May 2024

Tailoring disease control strategies for spring barley

With many spring barley crops at the stem extension stage, Head of Crops Knowledge Transfer at Teagasc, Michael Hennessy discusses the importance of knowing your varieties when selecting the most appropriate disease control strategy.

The weather forecasters tell us a high pressure will dominate our weather for the next week or so. This will allow ground to dry after all the rain and heavy showers over the past 10 days.

It has been an excellent time for planting late crops, allowing them to develop a strong base to provide every chance of returning a decent yield. However, we can’t get too complacent.

As we are now at the cusp of June, spring barley crops are experiencing warmer temperatures and longer days. This encourages the barley crop to transition as fast as it can into the stem extension stage, and almost all crops are at this stage at the moment.

The differences in harvest date between an early April sown and late April sown crop may only be as little as one week. This concentrates the growing season, lowering total biomass production and resulting in shorter crops and lower yields.

Hopefully, given the start we've had this year, the prospect of very low yields have receded. On the other hand, however, it is probably unlikely that the average yields for the farm will be broken or exceeded. Being conscious of the lower yield should also make you conscious of the potential output or potential margin. Lower yields equals a squeezed margin.

Disease control

Now that the weather is much drier, attention will turn to disease control in spring barley crops. Growers should not take a blanket approach to controlling disease, especially where there are a number of varieties planted on farm.

Consult the Department of Agriculture, Food and the Marine’s Spring Barley Recommended List 2024 to see if the varieties you’ve planted have good disease resistance.

Varieties with a strong disease package include: Geraldine; Gretchen; Mermaid; Spinner; and Rockway; with SY Amity a little further back. RGT Planet stands out because it is now quite susceptible to both Rhynchosporium and Net Blotch.

Generally the varieties with good disease resistance are free from disease, whereas Planet - particularly in a rotation following spring barley - is quite dirty with net blotch and some rhynchosporium.

As many crops may be only about two weeks until the flag leaf is visible, and this is close to the final fungicide application timing, there is a reasonable argument to monitor disease in the cleaner varieties and delay the first fungicide application if disease does not develop. This decision may be easier if the weather stays dry over the next couple of weeks.

In this scenario, one fungicide application targeted at Ramularia may suffice. Trials in Teagasc Oak Park tell us Revystar (plus Folpet) is one of the strongest products against Ramularia and, in terms of yield, Prothioconazole (Proline) plus a strob (plus Folpet) is a close second. There is potential to source generic products, which may represent value for your farm.

For those with Planet, there is little choice other than to apply a fungicide as soon as the weather allows or at the start of stem extension. It's advisable to use a reasonable rate of Prothioconazole (Proline) plus pyraclostrobin (Comet or generic form), as both of these are needed to control Rhynchosporium and Net Blotch in crops. A follow up fungicide treatment at awns peeping will be necessary on these crops, again with Ramularia the main target.