Given the unavailability of desmedipham to deliver early weed control in fodder beet and spring-sown crops, Teagasc is advising the use of phenmedipham and ethofumesate as the herbicides which will deliver the best results at the T1 growth stage.
Tillage specialist Ciaran Collins discussed the best herbicide options for beet in 2021 at the recent Teagasc Crops Update webinar.
He said:
“Phenmedipham products include Betenal Flo or Betenal Upfol, applied at rates between 0.4 and 0.5L/ha.
“Ethofumesate products include Oblix or Nortron. These can be applied at between 0.1 and 0.2L/ha.
“These herbicides should be applied to crops at the expanded cotyledon stage. Rates would need to be brought back a bit, if the plants are a bit smaller than this,” he added.
Spring-sown crops under stress
Collins continued: “If crops are under weather or nutrient stress, it is important to hold off the first herbicide application until the fodder beet recovers.”
Turning to spring beans, Teagasc’s Steven Kildea and Shay Phelan reported on the progress made by crops sown out in plots at Oakpark over recent weeks.
The purpose of the plots is to look at some of the key agronomy issues that relate to beans. They were sown out around the middle of March with a range of seed rates.
Shay explained:
“We want to see which seed rates work best in an Irish context. A sowing rate of 45 seeds per square metre should produce 30 plants per square metre.
“All the newly established plots were sprayed with Nirvana at a rate of 4L/ha.”
Pest control
Pest control is very important in bean and spring-sown crops with the impact of bean weevils already apparent within the Oakpark plots.
Shay Phelan said: “We start at the hedges and then move out towards the centre of the field to gauge the impact of any weevil damage that may have occurred.
“Weevil damage observed in the centre of a field would justify the application of an insecticide.”
According to Steven Kildea of Teagasc, chocolate spot is the main disease challenge in bean crops.
“It’s a wet weather disease mainly. So, in a wet summer growers should expect a lot of chocolate spot,” Kildea explained.
“The disease can have a significant impact, if it gets established. Leaf defoliation will follow.
“Growers should look out for chocolate spot after flowering and target a fungicide spray accordingly.”
Teagasc is recommending the use of Signum or a mix of amistar and tebuconazole to control chocolate spot.
Downey mildew and rust are other diseases that can impact on beans. Again, both thrive in mild, damp conditions.
Teagsc’s Eoin Lyons reported from just outside Enniscorthy on the progress made by a malting barley crop – variety Laureate – sown out on March 18.
“Plant counts are on target at around 300 per square metre. Nitrogen (N) management is key in crops destined for the distilling market,” he said.
“The target is to get a grain protein of 9.3% or less at harvest time.”
Malting barley growers in the Wexford area are applying N to malting barley crops at a rate of 135kg/ha at the one-leaf stage of crop growth, to ensure they meet the grain protein requirement.
Spring barley crops in the south of the country are currently at the four-leaf growth stage.
Measures to be taken
Key crop agronomy measures to be taken over the coming days will include: aphid, broad leaf weed and wild oat control.
Eoin Lyons continued:
“Teagasc research has confirmed that spring barley crops emerging in mid-April are very disposed to BYDV attack.
“An insecticide application on these crops will be necessary. Broadleaf weeds should be tackled at the four-leaf stage. Crops should be sprayed after four days of good growth and with the prospect of another four good days to follow.
“The wild oat herbicide can be applied in tandem with the T1 fungicide,” he concluded.