Article taken from the Farmers Guide
The reality of living without neonicotinoid seed dressings on oilseed rape is becoming apparent as cabbage stem flea beetle (CSFB) becomes active in crops across the east.
The pest will need careful monitoring to minimise damage to young oilseed rape plants, says Norfolk-based Agrovista agronomist Craig Green.
“The key danger period is from emergence to two true leaves. In really bad cases a CSFB attack can wipe out an emerging crop. Watch for signs of shot-holing caused by adults feeding and treat as soon as you see it.
“But be prepared to continue treating to the four-leaf stage if necessary where significant shot-holing continues to hold growth back.”
Foliar-applied pyrethroids are the only defence. “It’s not clear how much resistance there is. I’ll start with Afrisect (cypermethrin) as it has no non-target insect buffer zone requirement, but if control is not what is should be I’ll move onto lambda-cyhalothrin and then other alternatives if needs be.
“Look out for HGCA information for occurrences of resistance in your area, and be careful not to exceed application limits and to heed any new buffer zones requirements.”
Those still to sow OSR should aim to create a fine, firm, moist seedbed to encourage rapid germination and early growth to help plants outgrow the pest.
Applying up to 30kg/ha in the seed bed or soon after drilling will help further, he says.
The early harvest has provided a great opportunity for growers with black-grass problems to extend their out-of-crop control through repeat stale seedbeds before sowing cereals, says Craig.
“Cultivation to a maximum of 1.5in will allow volunteer cereals/OSR and black-grass to germinate quickly which can then be sprayed off with glyphosate.”
For more difficult weeds such as mugwort, nettle, volunteer OSR, groundsel and bindweeds, Craig will recommend Kyleo, which contains glyphosate, 2,4-D and surfactants to improve uptake, at 3 to 5 litres/ha plus 0.5 litres/ha of Companion Gold to enhance efficacy even further and reduce drift.
Repeating stale seed-beds to reduce the burden on cereal graminicides will be time well spent, he advises. Relatively dry soils at depth also provide an excellent opportunity to correct any soil damage, he adds.
“Take a spade out to the field and investigate if the middle of the field needs doing or just the tramlines and headlands. If subsoiling is needed, how deep is the problem? It might be satisfying to hear the tractor “bark” but the problem may only be 6-8in deep. Targeting the problem can save metal, diesel and time.”
Slug numbers are high in stubbles and standing crops so trapping and monitoring is imperative, says Craig. “Cultivations and rolled seedbeds help reduce numbers and the use of Redigo Deter on cereal seed will help against hollowing, but for high numbers, pellets applied through a calibrate pelleter will be the best option.”
Growers must heed Metaldehyde Stewardship Group guidelines in terms of application practice and maximum doses, he maintains. “What’s in Your Back Yard” is a useful website to identify high risk areas and create appropriate slug control programmes, including the use of alternatives like ferric phosphate.”
With so much black-grass following over from last year, growers need to adopt a zero tolerance approach early on, says Craig. Growers with a large cereal area to drill should pick their first-drill should pick their first-drilled fields carefully, leaving heavily infested ones until last.
“Wheat pre-em programmes will be mostly based around flufenacet and pendimethalin with the addition of Avadex (tri-allate) where black-grass is present. These herbicides should be applied as soon as possible after drilling. Last autumn too many growers made a quick start and kept drilling, and applied their pre-ems too late and in some cases didn’t get them on at all. The results were plain to see.”
Good application is also vital to ensure growers get the best performance, he adds.
Craig reports keen interest in cover crops this year, especially autumn-sown black oats and vetch recommended as a specialist mix for black-grass control and soil conditioning to aid the establishment of the following spring crop.
“Early drilled crops are doing very well with the recent moisture and look promising on a wide variety of soil types in Norfolk,” he says.
More growers are also experimenting with companion plants in oilseed rape, says Craig. “French trials have shown nitrogen capture typically reduces the need for bagged N by 30kg/ha. Companion plants also improve weed control, soil structure, crop rooting and pest control, typically delivering 0.2-0.3t/ha of extra yield.”
Craig Green is an agronomist with Agrovista, based at Great Ellingham, Norfolk (craig.green@agrovista.co.uk).
The reality of living without neonicotinoid seed dressings on oilseed rape is becoming apparent as cabbage stem flea beetle (CSFB) becomes active in crops across the east.
The pest will need careful monitoring to minimise damage to young oilseed rape plants, says Norfolk-based Agrovista agronomist Craig Green.
“The key danger period is from emergence to two true leaves. In really bad cases a CSFB attack can wipe out an emerging crop. Watch for signs of shot-holing caused by adults feeding and treat as soon as you see it.
“But be prepared to continue treating to the four-leaf stage if necessary where significant shot-holing continues to hold growth back.”
Foliar-applied pyrethroids are the only defence. “It’s not clear how much resistance there is. I’ll start with Afrisect (cypermethrin) as it has no non-target insect buffer zone requirement, but if control is not what is should be I’ll move onto lambda-cyhalothrin and then other alternatives if needs be.
“Look out for HGCA information for occurrences of resistance in your area, and be careful not to exceed application limits and to heed any new buffer zones requirements.”
Those still to sow OSR should aim to create a fine, firm, moist seedbed to encourage rapid germination and early growth to help plants outgrow the pest.
Applying up to 30kg/ha in the seed bed or soon after drilling will help further, he says.
The early harvest has provided a great opportunity for growers with black-grass problems to extend their out-of-crop control through repeat stale seedbeds before sowing cereals, says Craig.
“Cultivation to a maximum of 1.5in will allow volunteer cereals/OSR and black-grass to germinate quickly which can then be sprayed off with glyphosate.”
For more difficult weeds such as mugwort, nettle, volunteer OSR, groundsel and bindweeds, Craig will recommend Kyleo, which contains glyphosate, 2,4-D and surfactants to improve uptake, at 3 to 5 litres/ha plus 0.5 litres/ha of Companion Gold to enhance efficacy even further and reduce drift.
Repeating stale seed-beds to reduce the burden on cereal graminicides will be time well spent, he advises. Relatively dry soils at depth also provide an excellent opportunity to correct any soil damage, he adds.
“Take a spade out to the field and investigate if the middle of the field needs doing or just the tramlines and headlands. If subsoiling is needed, how deep is the problem? It might be satisfying to hear the tractor “bark” but the problem may only be 6-8in deep. Targeting the problem can save metal, diesel and time.”
Slug numbers are high in stubbles and standing crops so trapping and monitoring is imperative, says Craig. “Cultivations and rolled seedbeds help reduce numbers and the use of Redigo Deter on cereal seed will help against hollowing, but for high numbers, pellets applied through a calibrate pelleter will be the best option.”
Growers must heed Metaldehyde Stewardship Group guidelines in terms of application practice and maximum doses, he maintains. “What’s in Your Back Yard” is a useful website to identify high risk areas and create appropriate slug control programmes, including the use of alternatives like ferric phosphate.”
With so much black-grass following over from last year, growers need to adopt a zero tolerance approach early on, says Craig. Growers with a large cereal area to drill should pick their first-drill should pick their first-drilled fields carefully, leaving heavily infested ones until last.
“Wheat pre-em programmes will be mostly based around flufenacet and pendimethalin with the addition of Avadex (tri-allate) where black-grass is present. These herbicides should be applied as soon as possible after drilling. Last autumn too many growers made a quick start and kept drilling, and applied their pre-ems too late and in some cases didn’t get them on at all. The results were plain to see.”
Good application is also vital to ensure growers get the best performance, he adds.
Craig reports keen interest in cover crops this year, especially autumn-sown black oats and vetch recommended as a specialist mix for black-grass control and soil conditioning to aid the establishment of the following spring crop.
“Early drilled crops are doing very well with the recent moisture and look promising on a wide variety of soil types in Norfolk,” he says.
More growers are also experimenting with companion plants in oilseed rape, says Craig. “French trials have shown nitrogen capture typically reduces the need for bagged N by 30kg/ha. Companion plants also improve weed control, soil structure, crop rooting and pest control, typically delivering 0.2-0.3t/ha of extra yield.”
Craig Green is an agronomist with Agrovista, based at Great Ellingham, Norfolk (craig.green@agrovista.co.uk).