Matching oilseed rape variety type to drilling date can have a significant effect on whether growers triumph over flea beetle and create the foundation for a strong healthy crop the following spring, says Sarah Hawthorne do DSV UK.
Whilst the debate around whether early or late drilling is the best option continues, growers need to ensure whatever route the chose that they have a variety most likely to stack the cards in their favour, she believes.
“It’s an over-simplification to say it’s all down to vigour. High vigour is undoubtedly very important in the first 40 – 45 days after drilling so the plant establishes quickly but excessive vigour beyond this can be a problem rather than a benefit.
“What is more important is how vigour is exhibited at different stages of the growing cycle and how the plant responds to stresses at key stages.”
It is becoming increasingly clear that a variety’s ability to produce compensatory growth when damaged is critically important but so too is spring vigour, she says.
“Evidence from trials this year suggest that spring vigour is incredibly important, at least as important as autumn vigour growth and potentially more so.
“Strong hybrid varieties that are faster to develop before winter and start stem elongation earlier in spring can markedly limit damage from cabbage stem flea beetle larvae.
“In-built agronomic properties are important too as unseen diseases such as Verticillium Wilt and Turnip Yellow Virus (TuYV) can significantly weaken plants and make them less able to tolerate pest threats.”
“TuYV resistance can also help to protect the plant through its life cycle. Plants with high levels of TuYV infection will find it difficult to shrug off larval damage in spring.
“TuYV resistance helps protect the crop from the stress caused by repeated aphid attacks and viral infection plus it’s been noted that varieties with TuYV protection often have higher vigour profiles in the spring.”
The TuYV resistant variety Temptation has performed exceedingly well in Agrivice trials where flea beetle numbers have been monitored, Sarah Hawthorne explains.
“The variety’s exceptional flexibility, versatility and outright vigour means it is also ideally suited to both earlier and later drilling strategies.
“Planting early at the beginning of August means plants have day length and day light hours working in their favour, although this can result in a longer period where the beetles could be attacking plants and laying eggs.
“Drilling later means there is simply less chance of attack but valuable growing time is lost.
“In either situation, Temptation shows a good early vigour without the tendency to overgrow so that the winter hardiness of this variety is exceptional further adding to the chances of crop success. It also exhibits strong compensatory growth throughout the growing cycle.”
Temptation is on the AHDB RL for 2019/20 with a yield of 101% of control and has also been broadly introduced on the European continent with leading results in the important post official trials in France and Czech Republic, she points out.
“Besides its TuYV resistance the variety has a broad quantitative resistance against Phoma and a good tolerance against Verticillium Wilt – another largely invisible disease that can cause long-term stress to the plant and drastically reduce final yields.”
Whilst Temptation is one of DSV’s double-layer varieties having multi-gene resistance to Phoma Stem Canker and Light Leaf Spot plus TuYV resistance, two new high yielding triple-layer varieties coming through the UK testing system could further add to the ability of oilseed rape to tolerate pest problems.
“DSV Dazzler is one of the fastest autumn growing varieties available which could help significantly mitigate against the effects of flea beetle attack as it can quickly grow new leaves if attacked.
“Dazzler has good standing power so can tolerate being sown at higher seed rates. Strong autumn vigour and fast, early regrowth in spring help to compensate for any lost biomass in autumn and helps the plant to grow away quickly in spring.
“IN addition, RLM7 Phoma Stem Canker resistance helps in tighter rotations where there is greater risk of the disease.”
DSV Darling is another new high yielding triple-layer variety with high levels of compensatory growth and high levels of advantageous spring vigour, she says.
“Due to Darling’s high levels of vigour in the spring it can often benefit from a PGR application to ensure the canopy is optimised and well branched.”
In 2019/20 AHDB Candidate Trials, Dazzler and Darling have achieved 104% and 105% of control respectively
The genetic resistance to rapeseed pod shattering built into both varieties has been shown to dramatically cut seed losses around harvest, improving yields and reducing volunteer pressures, she says.
“This is especially valuable in protecting against summer storms, weather or workload harvesting delays or less than ideal combining condition.
“Even under low shattering pressures a few days harvesting delay could give significant harvest advantage over non shatter resistant varieties.”
Quad-Layers offer further yield stability and resilience
The first ever DSV ‘quad-layer’ oilseed rape varieties featuring enhanced disease resistance and physical properties to deliver high yields with minimal agronomic inputs could be available next year.
The total number of individual gene-related characteristics available on the layered varieties now totals seven covering resistances to Phoma Stem Canker, Light Leaf Spot, Turnip Yellow Virus, Clubroot and Pod Shatter together with Verticillium Wilt tolerance and Clearfield.
According to DSV UK’s Sarah Hawthorne, Breeding technology developed by the company is ensuring the usual complications of drops in yield and consistency when disease resistance and agronomic features are added to oilseed rape, are now eliminated, says Sarah Hawthorne
“The penalty for better disease resistance and agronomic functionality has historically been reduced yields, but modern hybrid breeding techniques are allowing us to quickly assimilate different genetic characteristics without yield drops.
“Furthermore, this can be done in a fraction of the time it used to take so we can react rapidly to demands from growers and move quickly to achieving our ambition of ‘drill and forget’ oilseed rape varieties.
“The developments allow us to build on a solid base of high gross output and strong genetic resilience in the face of more variable growing conditions and the reduced chemistry UK growers now have at their disposal.
“It is increasingly possible to add layers of disease resistance and physical properties without compromising yield and gross output in any way.”