Winter oats may need treated with a fungicide earlier than normal this spring, as crops face higher disease pressure following a relatively mild winter, according to leading agronomy firm Hutchinsons.

“If you’ve got disease present, you need to knock it out early to prevent problems getting established, becoming harder to control and compromising yield potential,” commented the firm’s technical development director Dr David Ellerton.

Typically, many winter oat crops receive two fungicides; the first at growth stage 32 (T1) usually targets mildew and crown rust, while the T2 at GS 55-59 is normally aimed at crown rust.

“Most crops are still some way off the GS 32 timing, which usually falls around early May, so consideration should be given to applying an early T0 fungicide to crops now prior to the traditional T1 timing.

“RGT Lineout with a rating of 3, and Dalguise, Grafton, Gerald, Fusion and RGT Southwark with a rating of 4, are all at high risk of mildew infection. For crown rust, Fusion has a rating of 3 and Gerald, Grafton and Dalguise have a rating of 4.”

For controlling mildew, Dr Ellerton recommends basing the T0 on proquinazid, which offers a high level of protectant activity or cyflufenamid if there is established infection to control. However, if cyflufenamid is applied at T0, it cannot be used in the subsequent fungicide applicationn.

"Prothioconazole +/- tebuconazole, or benzovindiflupyr, also offer some mildew control, while for crown rust, using a tebuconazole-based product at T0 prior to the T1 should the disease develop strongly.

Once crops reach T1, the newly-approved combination of benzovindiflupyr + prothioconazole, or tebuconazole +/- prothioconazole, all give good levels of crown rust knockdown. Greater persistence can be achieved by including strobilurins such as azoxystrobin , pyraclostrobin or fluoxastrobin in co formulation with prothioconazole.

Increasing Septoria threat

Dr Ellerton urges growers and agronomists to look out for Septoria avenae (Septoria leaf blotch).

“Symptoms range from dark-brown or purplish spots to larger spreading light brown lesions with yellow margins. Brownish black pycnidia can be seen with a hand lens, sunken in the tissue of larger lesions," Dr Ellerton commented, adding that control should be achieved by using fluxapyroxad in combination with triazoles such as mefentrifluconazole, however, Folpet does not have clearance for use in oats.