Crop Watch: Aphids strike combining peas

Foliar nitrogen applications on milling wheat and insecticide sprays on combining peas are key considerations this week, say our Crop Watch contributors.


Some high-yielding milling wheats would need foliar nitrogen to achieve the 13% protein threshold, said Wiltshire agronomist Dan Dines from Wessex Agronomy Services.

“But there appears to be a renewed debate on the use of late foliar nitrogen on milling wheats. While some millers are not keen on it, I fear that in higher-yield situations we will not hit protein requirements without it.”

In the meantime, care was required when applying late foliar nitrogen to avoid scorching stressed crops, he said.

Grassweed control has been variable and, in a number of cases, poor, he said. “Is this due to resistance? I feel poor conditions for herbicides this spring and a lack of crop competition have played a part.”

One positive was that it renewed focus on cultural controls, he said. “Management that was traditionally viewed as good practice, such as crop rotation, drilling date and cultivations, will have to be embraced.”

Hot weather in the south meant there was a serious brown rust threat in susceptible wheat and spring barley varieties, said Agrovista agronomist Swaran Bachoo from Hampshire. “Carefully monitor fields where the T3 fungicide was missed or a less than robust rate was used at T2,” he said. “Brown rust, even at this late stage, can lead to a yield reduction of up to 25%.”

Late spring bean variety Fuego was showing downy mildew symptoms and should be sprayed with Folio Gold (chlorthalonil + metalaxyl) as soon as symptoms developed. “These include felt-like, grey-brown growths on the underside of the leaf and yellowing on the top surface. This is a devastating disease which can lead to serious yield losses.”

Oilseed rape would be ready for desiccation in two weeks and glyphosate should be used in crops with low weed populations, he said. “Add the adjuvant Transcend to glyphosate to reduce seed loss from pod shatter. In weedy fields use Reglone (diquat) or Harvest (glufosinate ammonium).”

In Yorkshire, combining peas were beginning to flower, said David Martindale from Arable Alliance. “Aphid numbers are building fast in the recent warm weather and in most cases are exceeding threshold levels. An insecticide will need to be applied.”

Low disease pressure and correct fungicide timing meant wheat was clean down to leaf five, he said. New varieties only offered marginal benefits, so it was sensible to stick with known quantities, he said. “Winter barley is causing a headache with many wondering whether to reduce the acreage for 2011 or drop it all together. With more local biofuel plants coming on-stream the temptation will be to grow more wheat.”

Combining peas in Lincolshire received their second fungicide, which included an aphicide plus pyrethroid for pea moth, said AICC agronomist Ruth East. “A second dose of manganese was also included for the prevention of marsh spot.”

Spring beans were being treated with their second fungicide spray, which included an insecticide for bruchid beetle where pressure was high, she said. “Vining peas are being monitored for pea midge.”


Click below to read the full reports:

Crop Watch north – David Martindale

Crop Watch south – Swaran Bachoo

Crop Watch east – Ruth East

Crop Watch west – Dan Dines

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