Warm weather brings on the pests
19 October 2001
Warm weather brings on the pests
By FARMERS WEEKLY and FWi staff
RECENT warm weather has been damned as much as it has been welcomed by growers pressing on with the autumn workload.
Most farmers across the south and midlands have now completed drilling, apart from fields following sugar beet and potatoes.
Cereal and oilseed crops have thrived in the warm, moist conditions … but so have the pests, the pathogens and the weeds.
“Ive got resistant Italian ryegrass growing faster than the crop,” says Shropshire-based independent agronomist Bryce Rham.
“Its super that everyones finished drilling, but the weeds are growing fast and the crops are looking extremely lush.”
In Lincolnshire, Aubourn agronomist Jonathan Holmes has advised two growers with extreme blackgrass problems to spray off with glyphosate and re-drill.
“The growers couldnt get the pre-emergence spray on because it was too wet and windy and now the blackgrass is like the hairs on a cats back,” he says.
Despite destroying two good chits of blackgrass pre-drilling, without a residual pre-emergence spray the blackgrass has flourished too.
“Lexus (flupyrsulfuron-methyl)/Hawk (clodinafop-methyl+trifluralin) plus oil might kill the blackgrass, but the chances are it wont get all of it and, with it so warm, we are sure to get crop damage.”
In Hampshire, Crop Management Systems Mark Glyde reports aphids have been a huge problem: “Weve got absolutely loads of them on cereal and rape crops.”
Most crops are treated with Secur (imidacloprid) to protect against Wessex flea beetle and this also keeps the aphids at bay.
But he warns that this could now be very dilute, especially in early-drilled crops with a low seed rate, and advises growers to spray a pyrethroid.
FWi Farmer to Farmer crop diarist Andrew Cullinane in Kent has been enjoying the “shirtsleeves weather”, but disease has hit his knee-high rape crop.
“I have never seen quite so much phoma pressure as this year, but all our crops have now been treated with a fungicide,” he writes.
In Wiltshire, Chris Redfearn has also found phoma in his Fortress oilseed rape: “Delaying action can be disastrous, especially if the plant is small.”
But spraying lush, soft cereal crops can be dangerous, especially if there is a frost due.
Farmacys Jim Butchart advises growers to leave an interval of at least 14 days before spraying after a pre-emergent spray if blackgrass is still emerging.
He remembers a similar situation in 1983 when there were many cases of crop scorch and plant loss from early post-emergent sprays and overlaps.
But Hampshire Arable Systems Steve Cook warns growers of being overcautious, pointing out that 1984 was a bumper harvest.
“You may have to accept some crop damage to make sure sprays get on. You do not want the first frost on a crop that has only just been sprayed.”
- For more detailed advice on herbicides, refer to this weeks FARMERS WEEKLY.
- Farmer to Farmer – find out the latest from the FWi farm diarists
- Experts warn of aphid explosion, FWi, 18 October, 2001
- FWi Arable – our arable news page
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