South: Timing T0 fungicide around the weather.

Optimal T0 fungicide timing targets final leaf four fully emerged – too early an application can lead to a big gap before T1 and allow disease to take hold. I’ve been dissecting samples to determine leaf emergence and early drilled wheat was there a week ago, late drilled fields won’t be due for another 10 days.

Most will be at leaf four emerged over Easter, however a cool dry March has meant that crops have developed slowly, and whilst septoria is very evident, it has been held by the weather. Don’t get despondent if the weather delays application – better to wait than go too early, T0 timing is not as critical as T1 and T2.

Oilseed rape is extending and close to yellow bud. Disease is under control, thanks to an early SDHI, though active light leaf spot was seen on a spray miss last week. No significant pollen beetle numbers have been seen yet in field or traps. Hopefully we’ll reach flowering without an insecticide, but I’m still monitoring each field. Spring beans and peas are mostly in and beginning to emerge, so monitor for weevil notching and treat if needed.

With low crop prices input costs are under scrutiny. Focus on the potential value of each pass through the crop. Yield response data is invaluable in selecting products to solve particular problems, and getting optimum value is essential. Time T0 to avoid a wide gap to T1 in wheat, monitor pest thresholds in rape, peas and beans, and ensure you gain maximum efficacy from rates applied.

Test your water and if hard, add a conditioner to the tank before filling. Choosing an effective insecticide to control pollen beetle is one thing, but having your rate reduced by 40% due to calcium lock up is bad practice and poor value for money. Time your applications and apply well to gain best effect (check weather, spray quality, water volume, leaf dryness and drying time).

Reducing passes through the crop saves fuel, but beware when tank mixing. Manganese and CMPP in the same mix can precipitate and in rape, if you want a spectacular gloop in the spray tank then a mix of boron and tau-fluvalinate (Mavrik) takes some beating.

If saving time on fill ups, be aware that some water volumes are statutory. My potato, carrot and parsnip pre-emergence herbicide mixes have contained linuron (Afalon/Datura), so need at least 300l/ha of water. After my trials last season I’m now using an adjuvant (Retainer) to prolong activity of residuals, and reduce their potential for crop damage, so gaining best value (and hopefully reducing the spend on further herbicides).

It’s heartening to see that attention to soil health, organic matter and cover cropping as a tool in our armoury is being taken up more widely – it’s even made it to Ambridge!

In between showers, and trying to find a spray window, have a happy Easter.

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