Article taken from the Agronomist & Arable Farmer
Oilseed rape growers will need to work hard this summer to ensure their crops establish quickly and evenly.
Plants that are slow to get away are most prone to cabbage stem flea beetle attack, as shown graphically in some areas last season following the ban on neonicotinoid seed treatments, says Agrovista technical manager Chris Martin.
“Some crops were so badly damaged they were written off, with areas in Bedfordshire and Hertfordshire particularly badly affected,” he notes.
DEFRA’s recent decision not to grant emergency use of neonicotinoid seed treatments in areas most in need could mean many of the worst-affected growers will not risk a repeat this season, says Mr Martin.
However, he believes most other growers will stick with the crop, albeit in some cases on a smaller area, especially now the rapeseed market appears to be staging a much-needed recovery.
“Establishing a small-seeded crop at low seed rates during the summer can pose a significant challenge at the best of times, say Mr Martin. “This is demonstrated by the enormous variability we see in plant populations and eventual yields every season.
“Slow-growing crops will be more susceptible to all seedling pests and diseases, but are especially prone to early attack from cabbage stem flea beetle, which can wipe out a backward crop as it struggles to come through the ground. However, by following a few simple guidelines, growers can help crops to grow away strongly, tipping the odds very much in their favour.
OSR establishment has been at the heart of Agrovista’s Growcrop Gold trials, carried out over a range of sites across the UK over the past six years. These show that the highest yields tend to be achieved with lower seed rates on good seedbeds with adequate moisture, giving evenly established low plant populations in the autumn, says Mr Martin.
“By getting the right plant population from the outset we stand a much better chance of achieving the optimum canopy toward the end of flowering, which is the crucial period when seed is set.”
The first step to successful establishment is to remove compaction, he advises. “Oilseed rape is a lazy rooter and needs soils with plenty of cracks and pores so it can put down the deep taproots that underpin high yields. The crop is also very intolerant of waterlogging.”
Locating the position of any soil pan is important to cure, rather than create, problems. “Use a spade or a penetrometer to ensure remedial cultivations are carried out at the right depth. Going too deep will compress the compaction layer from below and increase when slippage.”
A good seedbed is next on the list. Maintaining moisture is critical, so cultivations should be kept to the minimum possible to achieve a seedbed that contains a mix of fine soil and small aggregates.
Fine Balance
“We want to encourage good seed-to-soil contact while minimising capping. It’s a fine balance, but the trick is not to overwork soils and roll them straight after drilling to conserve moisture in the surface layer.”
Optimum seed depth is 15mm, though growers should check pre-emergence herbicide labels first to ensure this is permitted. The best way to achieve this is by conventional drilling, though sub-casting can achieve good results, or coulters can be fitted to the back of subsoiler legs. Manufacturers are also developing their own systems.
Establishing the correct plant population is vital to achieving consistent yields, Mr Martin. “Several years of Growcrop Gold work has shown that highest yields are typically achieved by sowing 15-20 seeds per m of row to produce 12 -15 plants.”
As a rule of thumb 40-60 seeds/sq m will achieve an acceptable result at 12.5-25cm spacing, where normal establishment is expected. However, at 50cm spacing this would produce 30 seeds/m of row, so seed rates should be reduced accordingly.
“Establishing more than 12-15 plant creates too much early competition. Plants fight for light, which reduces establishment and tends to produce tall, spindly plants that are more prone to pest attack. Too high a seed rate also wastes money.”
Correct plant spacing alos encourages crops to produce open, branched architecture the following spring that makes best use of sunlight and optimises yields, Mr Martin adds.
Where higher levels of flea beetle attack are predicted, seed rates can be increased, but narrower row spacings must be used rather than cramming more seed along the row.
“The rule of not exceeding 60 seeds/sq m should still be observed. If growers remain uneasy they should choose varieties with the best early autumn vigour.”
Phosphate is an important nutrient to aid early crop growth. The nutrient is immobile so accurate placement is important as small rape plants have poorly developed roots.
“Place soluble phosphate fertiliser alongside and just beneath seeds to produce optimum results,” says Mr Martin.
Growers who do not have access to specialist kit can achieve good results by incorporating phosphate into the top inch of seedbed, he adds.
Mesurol seed dressing has an effect on flea beetle and is legally available on imported seed.
“It can help in some situations, though results are not overly consistent,” he notes.
“In addition, mesurol is not systemic, so well-timed, approved pyrethroid sprays will still be needed to combat flea beetle. Be prepared to spray at the first sign of shot-holing.
Oilseed rape growers will need to work hard this summer to ensure their crops establish quickly and evenly.
Plants that are slow to get away are most prone to cabbage stem flea beetle attack, as shown graphically in some areas last season following the ban on neonicotinoid seed treatments, says Agrovista technical manager Chris Martin.
“Some crops were so badly damaged they were written off, with areas in Bedfordshire and Hertfordshire particularly badly affected,” he notes.
DEFRA’s recent decision not to grant emergency use of neonicotinoid seed treatments in areas most in need could mean many of the worst-affected growers will not risk a repeat this season, says Mr Martin.
However, he believes most other growers will stick with the crop, albeit in some cases on a smaller area, especially now the rapeseed market appears to be staging a much-needed recovery.
“Establishing a small-seeded crop at low seed rates during the summer can pose a significant challenge at the best of times, say Mr Martin. “This is demonstrated by the enormous variability we see in plant populations and eventual yields every season.
“Slow-growing crops will be more susceptible to all seedling pests and diseases, but are especially prone to early attack from cabbage stem flea beetle, which can wipe out a backward crop as it struggles to come through the ground. However, by following a few simple guidelines, growers can help crops to grow away strongly, tipping the odds very much in their favour.
OSR establishment has been at the heart of Agrovista’s Growcrop Gold trials, carried out over a range of sites across the UK over the past six years. These show that the highest yields tend to be achieved with lower seed rates on good seedbeds with adequate moisture, giving evenly established low plant populations in the autumn, says Mr Martin.
“By getting the right plant population from the outset we stand a much better chance of achieving the optimum canopy toward the end of flowering, which is the crucial period when seed is set.”
The first step to successful establishment is to remove compaction, he advises. “Oilseed rape is a lazy rooter and needs soils with plenty of cracks and pores so it can put down the deep taproots that underpin high yields. The crop is also very intolerant of waterlogging.”
Locating the position of any soil pan is important to cure, rather than create, problems. “Use a spade or a penetrometer to ensure remedial cultivations are carried out at the right depth. Going too deep will compress the compaction layer from below and increase when slippage.”
A good seedbed is next on the list. Maintaining moisture is critical, so cultivations should be kept to the minimum possible to achieve a seedbed that contains a mix of fine soil and small aggregates.
Fine Balance
“We want to encourage good seed-to-soil contact while minimising capping. It’s a fine balance, but the trick is not to overwork soils and roll them straight after drilling to conserve moisture in the surface layer.”
Optimum seed depth is 15mm, though growers should check pre-emergence herbicide labels first to ensure this is permitted. The best way to achieve this is by conventional drilling, though sub-casting can achieve good results, or coulters can be fitted to the back of subsoiler legs. Manufacturers are also developing their own systems.
Establishing the correct plant population is vital to achieving consistent yields, Mr Martin. “Several years of Growcrop Gold work has shown that highest yields are typically achieved by sowing 15-20 seeds per m of row to produce 12 -15 plants.”
As a rule of thumb 40-60 seeds/sq m will achieve an acceptable result at 12.5-25cm spacing, where normal establishment is expected. However, at 50cm spacing this would produce 30 seeds/m of row, so seed rates should be reduced accordingly.
“Establishing more than 12-15 plant creates too much early competition. Plants fight for light, which reduces establishment and tends to produce tall, spindly plants that are more prone to pest attack. Too high a seed rate also wastes money.”
Correct plant spacing alos encourages crops to produce open, branched architecture the following spring that makes best use of sunlight and optimises yields, Mr Martin adds.
Where higher levels of flea beetle attack are predicted, seed rates can be increased, but narrower row spacings must be used rather than cramming more seed along the row.
“The rule of not exceeding 60 seeds/sq m should still be observed. If growers remain uneasy they should choose varieties with the best early autumn vigour.”
Phosphate is an important nutrient to aid early crop growth. The nutrient is immobile so accurate placement is important as small rape plants have poorly developed roots.
“Place soluble phosphate fertiliser alongside and just beneath seeds to produce optimum results,” says Mr Martin.
Growers who do not have access to specialist kit can achieve good results by incorporating phosphate into the top inch of seedbed, he adds.
Mesurol seed dressing has an effect on flea beetle and is legally available on imported seed.
“It can help in some situations, though results are not overly consistent,” he notes.
“In addition, mesurol is not systemic, so well-timed, approved pyrethroid sprays will still be needed to combat flea beetle. Be prepared to spray at the first sign of shot-holing.