West: Oilseed rape flowering is extremely variable

Some of my colleagues have been gently reminding me about my recent article in the 2011 Bayer Spring Crop Focus in which I stated that the 25% less rainfall we experienced in spring 2010 was “likely to be the exception rather than the norm”. But having had around 10mm here since the beginning of March, conditions are now extremely dry.

Temperatures reached 24C here at the end of last week. Some growers have been lucky enough to be situated under a thunderstorm over the last few days, but the storms have cleared pretty quickly. We have also been experiencing heavy dews over the last 7-10 days which has meant that crops have been wet in the mornings.

In winter wheats, yellow rust has appeared in crops of Oakley that did not receive a T0 fungicide seven days ago. They went from nothing to major infection in the space of a week. Mildew is the worst I have seen for some time, with Diego the worst affected, despite all the late frosts. I think that the primary reason is the stress levels being placed upon crops.

Irrigators are out and about on light land wheat crops in Shropshire. There are two blocks of Grafton second wheat where Diego was finished off before the Grafton was started and in both situations, the Grafton is much greener and less stressed than the Diego. 

However, despite the drought conditions, most crops are coping quite well. Light land crops with no inherent fertility have been hit hardest with tiller loss occuring. All wheat has had a T1 fungicide with a strobilurin of some description to prevent any further outbreaks of yellow rust.

Early-sown Humber and Grafton have leaf two fully out with the flag leaf thinking of poking through. Some crops will be 21 days from T1 to T2 by Friday, 6 May. We will decide what we to do nearer the time dependent on rainfall events or not and consider stretching the interval.

Barley crops are just starting to poke out the awns and will more than likely look at T2 next week. Some good crops on strong ground will have Terpal (2-chloroethylphosphonic acid + mepiquat chloride) applied this week, but we will generally steer clear of applying growth regulators on most barley crops.

Winter oilseed rape crops are anywhere from 25-80% flowering. Cubic is the most forward with the main raceme having 80% developed pods and petals dropping with a percentage sticking to the leaves. We will be starting applications this week on most crops. Some light land crops appear to be aborting flowers with pods being small. There is also evidence of frost damage to late crops, primarily after pigeon damage. I have found seed weevils in some crops and I have also seen two crops with significant club root symptoms.

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