Teagasc tillage specialist Shay Phelan has reviewed the fungicide options for winter barley and winter wheat, along with weed and disease control options.
Where winter barley is concerned, there are reports of early maturing varieties (e.g., Joyau) having awns emerged or will be emerged in the coming days.
So now is the ideal time to apply the final fungicide to crops. Growers should target the awns peeping stage for the final application.
“Trials from Oak Park clearly show that waiting until growth stage (GS) 59, when heads are fully emerged, will lower yields by up to 0.4 t/ha,” Phelan explained.
Trials have also shown that 50% rates of an azole SDHI/strobilurin mix (e.g., Siltra, Elatus Era, Decoy + Priaxor) will be sufficient and mix these with a full rate of Folpet 1.5L/ha for ramularia control.
Fungicide
Most early sown crops of winter wheat are due their leaf-three fungicide application now.
This is the ideal timing for the first fungicide, which should ensure that crops remain clean up to the flag leaf stage. The next task for winter wheat is to apply the final split of nitrogen – typically 25% of the total.
“With the recent fall in grain prices, how much nitrogen in total should be applied will depend on the price that the nitrogen was bought for,” Phelan commented.
“Those who bought before Christmas paid the highest prices.
“So, applications above 200-210kg/ha will probably struggle to be economic given the value of the extra grain versus the cost of that nitrogen.”
It is now getting very late for drilling spring barley crops. Growers should only continue to do so where there is the expectation of the crop covering its costs.
The following rule of thumb is relevant – target a yield of about 6-7t/ha and cap the spend on inputs.
Growers should complete all remaining nitrogen applications on spring barley crops. They should also continue to monitor crops for nutrient deficiencies.
Weed control
There are reports of manganese/magnesium deficiency symptoms in crops. Where symptoms are present, growers should include a suitable product to help rectify the deficiency.
According to Shay Phelan, Barley Yellow Dwarf Virus (BYDV) risk is higher this year, especially with April-sown barley crops.
“It is important to walk crops and search for aphids. If aphids are present, a pyrethroid insecticide should be applied at the three- to four-leaf stage,” Phelan explained.
Phelan confirmed that weed control was difficult last year in spring barley crops. This was especially the case with acetolactate synthase (ALS) resistant weeds, including chickweed, poppy and corn marigold.
These weeds should be targeted first and the mix should contain a non-ALS partner that has activity on the target weeds.
The lesson from 2022 was that large chickweed was very difficult to control, so there is no room to delay herbicide application once the first flush or weeds have appeared.
Where disease control in spring barley crops is concerned, growers should target fungicide application at mid/late tillering in the early sown crops (i.e., those sown in late-February/early March).
This can increase yield by as much as 0.3t/ha over delayed application at GS31/32 in high disease pressure situations.
Growers should use 50% rates of any of the fungicide mixes (e.g., Decoy/Comet, Macfare Expro, Siltra, Elatus Era etc.) which will give sufficient control. There is no benefit in adding Folpet at this stage.