Leatherjacket Report – Autumn Update 30th September 2014

crows and rooksRecent reports of adult crane-flies in Central England and Northern Ireland mean growers need to be alert for damage. Earlier this spring the SRUC reported numbers in the soil at the highest recorded levels in 39 years.

Adult crane-flies lay eggs July-September particularly on grassland or in “grassy” stubbles. Hatched leatherjackets are vulnerable to desiccation especially when young, however the rainfall forecast next week may aid their survival. Growers should be alert for any damage particularly on newly established cereals and grass leys.

Leatherjacket Damage Thresholds

 >0.3-0.5 million/ha (30-50/m2) Damage likely in new ley or cereal
 >0.5-0.6 million/ha (50-60/m2) Autumn population in grassland likely to cause damage in following cereals.
 >1 million/ha (100/m2) Population in permanent grass where treatment likely to give economic benefit.
 >2 million/ha (200/m2) Population in permanent grass likely to show visible damage if untreated.

 

crows and rooks

Crows and rooks feeding on larvae

leatherjacket larvae

Leatherjacket larvae


Action

Fields with a history of leatherjacket damage should be monitored for large numbers of rooks and crows feeding on the larvae. Risk assessments and testing for the presence of leatherjacket larvae will provide a good indication of fields that are most likely to need treatment.

For cereals applications may be made from post-drilling.

Find out more about controlling leatherjackets in grassland and cereals.

If treatment is justified use Equity® at 1.5 L/ha applied in 200 to 1000 litres of water/ha.

If using Dursban® WG at the recommended rate is 1.0 Kg/ha applied in 200 to 1000 litres of water/ha.

Be aware control will be reduced if soil temperatures are below 5°C or soils are dry as the larvae will move deeper into the soil profile.

Use low drift nozzles and extend buffer zones to preserve Dursban WG and Equity use.

For conventional boom sprayer:

  • Use LERAP – low drift – three star nozzles
  • AND adopt a 20 metre no-spray buffer zone (1 metre for dry water bodies)

Say No to Drift

 

 

 

Beating Beans in cereals in vital in the blackgrass battle

vol_bean_trial_NorfolkVolunteer beans in cereals must be controlled in the battle against blackgrass, warns John Humphreys, Dow AgroSciences national business manager.

Under the CAP three-crop rule more farmers are considering pulses in their rotations, he points out; and because they may no longer use CMPP (mecoprop) products in the autumn, controlling emerging grass weeds could become harder.

“Volunteer beans tend to grow in clusters and quite quickly, so they can soon shade the grass weeds,” explains Mr Humphreys.

“As grass weed control in cereals becomes ever more difficult, farmers need to maximise the weed target to give post-em graminicides the best chance to work. That means removing any beans as soon as possible.”

Spray grassland weeds now

Dr. Simon Pope, Crop Protection Manager, Wynnstay.

Dr. Simon Pope, Crop Protection Manager, Wynnstay.

 

Warm soils and heavy dews are providing ideal growing conditions for grassland weeds such as docks, thistles and dandelions, so it is a good time to control them, according to Wynnstay’s Crop Protection Manager Simon Pope.

“Autumn is often overlooked when it comes to spraying weeds in grass fields – but actually there are good reasons for doing it at the end of the season,” he says.

“As day-length shortens and perennial weeds move from reproductive to vegetative growth patterns, they switch their internal transport systems around. Instead of moving nutrients up into their leaves, they start pumping them down into their roots, to build food stores for winter. This means any translocated herbicide applied now is immediately carried deep into the root network to affect a good kill.

Tackle dandelions when they are green

“It is also a great time to tackle dandelions – which ideally should be sprayed before flowering for best results. Once a field has turned yellow with flower heads in late April/early May, it is too late to get great control. Many farmers miss the boat in spring. But in September and October, the dandelions are putting on strong leaf growth again, providing an ideal opportunity to spray with a good translocated product like Pastor.”

Dandelions at green leaf stage

Dandelions are putting on leafy growth which is ideal for spraying with herbicide

Dr. Pope goes on to say: “Spraying now may also help ease workload next spring. The treatment window was unusually long this year with plenty of time before first cut – but most years this can be just a few weeks. Hitting the weeds now may preclude the need to spray next spring and give silage and grazing swards a clean start to the season – whatever the weather throws at us this winter.”

As with spring spraying, it is important to follow basic rules to ensure good results when applying herbicides.

“Essentially farmers need to get a lethal dose into the root,” explains Dr. Pope. “For this to happen there has to be sufficient leaf area and the plant has to be actively growing. Using the best product for the target weed, at the right rate, in the right amount of water is also very important.”

Agronomy Update – 10 September 2014

In this Edition

Drilling cereals Mundford Norfolk2 - 9-11-12Which pre-emergence for grassweeds in winter wheat?
Complete the programme to control weeds in grassland.
Reduce winter N losses from FYM, biosolids or digestate.

This Edition’s FAQs:
Does Dow AgroSciences have anything for Cabbage Stem Flea Beetle in rape?
What do you think about Centurion Max in Oilseed Rape grassweed programmes?
Can I use Galera this autumn?

Dates for the diary

Action plan needed for Blackgrass

Blackgrass in wheatContinuing with current practices to fight the growing threat of blackgrass in winter wheat is not a solution, says Dow AgroSciences Stuart Jackson; farmers need a comprehensive action plan for autumn 2014.

The action plan, which should be developed as soon as possible, begins by reviewing crop rotation.