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Canker resistant variety? Dont rip up the fungicide programme


New research has revealed that oilseed rape varieties with high scores for canker resistance can still deliver improved yields when subjected to a high input fungicide programme, questioning the advantage of canker resistance.

Trials conducted through NIAB TAG over the last three seasons under the National Agricultural Centre Initiative (supported by The Morley Agricultural Foundation), have shown how yields of canker resistant varieties of OSR – Excel and ES-Astrid still undergo notable yield increases, in comparison with the untreated control, following an intense fungicide treatment programme.

Dont throw away your fungicide programme simply because you purchased a canker resistant variety, advises Ron Stobart, agronomist at NIAB TAG. Continue monitoring the crop and treat if 1 in 10 plants show signs of infection for low canker resistant varieties and 1 in 5 for the higher resistant varieties.

Within the trial, six varieties of OSR were grown under three different conditions untreated, low input and high input. All varieties showed yield responses to fungicide inputs for phoma control, even those varieties with higher resistance, explains Mr Stobart. Within the series of experiments, on average over all varieties, the low input programme (one fungicide spray) gave an response of around 0.1 t/ha over untreated plots, where as the high input programme (three fungicide sprays) gave an response of 0.2 t/ha.

Interestingly though, the average yield increase over the three years to a high input programme (compared to untreated plots) was very similar for varieties with high canker resistance scores like Excel and Es-Astrid and for varieties with lower resistance scores such as Excalibur and older susceptible varieties like Winner, points out Mr Stobart.

With the current weather conditions being favourable for phoma, growers need to consider the risks carefully. The 20 days of rain we have already had since 1st August will be enough to trigger onset of the disease and September is the time when fruiting bodies are releasing spores. These will travel on the wind and infect surrounding fields. The most visible symptoms to look for are lesions on the leaves; these areas will also produce spores which will infect more of the crop when rain falls. says Mr Stobart.

Mr Stobart also emphasised the importance of taking action at this stage in the phoma lifecycle, as once the disease is deep seated at the base of the stem there is little you can do to prevent the development of cankers in the spring. The canker infected stems will restrict the function of the plant and will not only reduce yield but can also weaken the stem and increase lodging risk.

Part of The NIAB Group, TAG is the UKs largest independent agronomy service, with influence across more than 20% of the UKs arable area. TAG provides impartial agronomic information across a range of crop types, cultivations, spray technology, environmental schemes and agronomic inputs, using information drawn from over 20 trial locations throughout England.

The National Institute of Agricultural Botany (NIAB) is a pioneering plant science organisation based at the heart of the Cambridge science, technology and university communities and a thriving UK agricultural industry. It has an internationally recognised reputation for independence, innovation and integrity and is ideally placed to meet the industrys current and future research and information needs. Founded in 1919, NIAB has over 90 years experience in the agricultural and food sectors in crop research, trialling and knowledge transfer.

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