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26 May 2021

Sustainable stem canker resistance

As featured in Arable Farming Magazine

Sustainable stem canker resistance

by Arable Farming

New traits coming to the market bring advances in disease resistance and nitrogen use efficiency in winter oilseed rape.

A new source of resistance to phoma stem canker, labelled RlmS, will confer effective and sustainable resistance to the disease, says plant breeder LS Plant Breeding (LSPB).

The company is introducing RlmS to the UK market in two varieties: Respect and Flemming.

Respect is a hybrid set to become a new benchmark for plant health and yield stability, says LSPB.

Along with its resistance to phoma stem canker, it is also said to have a high, consistent yield performance and vigorous growth habit in autumn and spring regrowth.

The variety was added to the AHDB Recommended List (RL) for the East/West region for 2021/22.

Flemming is another first for the UK market as a next generation hybrid with stacked traits, adding turnip yellows virus resistance (TuYV) to the RlmS resistance.

A RL candidate variety, it is due to be considered for addition to the RL this autumn.

Flemming promises the same yield performance and autumn vigour as Respect with a more prostrate growth habit, says LSPB.

Chris Guest, LSPB managing director, explains the innovations behind RlmS.

This gene was identified by breeders at NPZ, LSPBs shareholder, who have been researching phoma resistances for decades. It was integrated into our breeding programmes and developed into a viable trait for commercial varieties. Genetics It is important to note that the RlmS gene is distinct from those widely found in current oilseed rape varieties. Hence, by developing our hybrids with different genetics, we give extended and resilient phoma resistance in the field.

The unique phoma resistance is also associated with strong overall plant health and the gene has especially good stem resistance that brings better protection against the increasingly important pathogens of verticillium and sclerotinia. While cabbage stem flea beetle is seen as the major current threat by growers, it should be emphasised that stem canker/phoma is one of the most important diseases in oilseed rape that has widespread and regular occurrence, taking up to 50% off yield potential.

It is estimated that total economic losses from the disease reach about £100 million each season.

The oilseed rape area is set to rebound to sustainable levels this autumn as, by most measures, it is the best break crop on a gross margin basis. The heightened resistance from our new varieties to stem canker/phoma and added TuYV resistance will be an important weapon in the armoury of growers.

Other winter OSR varieties to have emerged from the LSPB breeding programme in recent years have included clubroot resistant varieties Croozer and Crome, plus the HEAR variety Resort, which are all currently on the Recommended List.

Respect and Flemming are a new and exciting generation of hybrids, concludes Mr Guest.

Breakthrough sclerotinia tolerance trait

The first winter oilseed rape variety with a claim for tolerance to the stem disease sclerotinia has recently been launched by Pioneer, the seed brand of Corteva Agriscience.

The Pioneer Protector Sclerotinia PT303 hybrid has gained National Listing and the results from the independent AHDB Candidate List trials have been published.

PT303 has delivered the highest gross output yields in each AHDB region including a UK region yield of 111%.

It was ranked first with a gross output yield of 116% in the East/West region and also topped the North region with a yield of 105%.

PT303 also delivers turnip yellows virus and RLM7-based phoma resistance.

In Corteva trials with sclerotinia infection levels at 25% or above, the severity of the disease was reduced by up to 75%.

Trials also showed the higher the severity of disease, the greater the benefit from the trait.

Corteva Agriscience seeds and inoculants sales manager Andy Stainthorpe says: Pioneer Protector Sclerotinia PT303 gives farmers the ability to reduce the incidence of disease and manage their crop protection applications with greater flexibility and assurance.

With environmental effects such as global warming, sclerotinia is becoming a bigger burden for farmers during increasingly humid and wet weather.

As domestic agricultural policy evolves and farm businesses pursue a more efficient, productive future, PT303s potential to limit the development of sclerotinia could be a significant component of disease control strategies. Sclerotinia only strikes every so often, but when it does it is hugely damaging to yield.

Having identified a genetic source of sclerotinia tolerance, Corteva breeders have spent more than a decade crossing that source into our regular hybrids through traditional breeding. Milestone No products have previously offered any level of resistance to sclerotinia but with PT303 we now have a variety that has tolerance a major milestone in our industry.

PT303 scores 6 for light leaf spot resistance and 7 for stem canker in AHDB trials and has proven turnip yellows virus resistance, adding an extra layer of protection for growers.

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