In this month’s Crop Walk and Talk Steven Gate of Agrovista, highlights the agronomic issues affecting wheat, barley and oilseed rape crops near Penrith, Cumbria. Abby Kellett reports.
Despite a predominantly dry winter, significant rainfall during March resulted had aided septoria development while poor soil conditions meant fertiliser application was delayed in many areas across the region.
A turn in the weather during the last week of March allowed the first of the nitrogen to be applied, causing a surge of spring growth.
But with a large amount of septoria visible on the lower leaves of winter wheat crops, as well yellow rust, in some instances, Mr Gate said growers should consider a pre T0 fungicide application.
“Where crops have high levels of active septoria, and where the T0 timing is still some way off, I would probably add a minus T0 fungicide in the form of chlorothalonil, to help clear up some of the over-winter septoria on the older leaves and to protect the new leaves.”
On inspecting the growth stage of a crop of Graham drilled on October 10, Mr Gate predicted the T0 timing - marked by GS30 - would be between April 5 and April 10.
He said: “I dictate my GS30 timing three weeks before I would potentially be looking to apply my T1. Looking at the stage crops are at, we will be looking at applying a T1 between mid and late April.
See also: VIDEO: Delayed drilling dampens disease
“We will put some protection on, in the form of chlorothalonil, along with a little bit of triazole for some eradication activity.”
Assessing weed populations ahead of the T0 timing is useful in determining whether a broad-leaved weed herbicide is required alongside the T0 fungicide, he added.
Where crop growth had been most rapid, powdery mildew was identified on several plants, warranting the need for an early mildewicide.
“In more forward lush crops, we can easily find powdery mildew in the stem base. Protection is key in dealing with the disease in winter wheat, as eradication is pretty unsuccessful.”
The combination of slow migration and advanced crop growth meant pollen beetle was of little threat to OSR crops. With some crops beginning to flower, pollen beetle will help pollinate the crop going forward and so an insecticide will not be necessary, said Mr Gate.
More urgently, growers should be thinking about applying their first sclerotinia spray.
“As the crop approaches flowering, we contemplate the start of the sclerotinia programme. This will include a strobilurin and a triazole, which will have a growth regulatory affect, and we will look to follow that up at mid-flowering, or first petal fall, with an SDHI.
“This second spray will contain some amino acids to aid pod set,” he said.
While the crops assessed showed little in the way of disease, he identified the first sclerotinia spray as an opportunity to control phoma and light leaf spot that had survived the winter.
Evidence of boron deficiency was found on some plants, characterised by the splitting of the main stem. However, at this stage in the season, treatment would be ineffective. Instead, growers should look to rectify soil micronutrient levels in the autumn.
On inspection, barley crops were nearing GS31. “The developing ear is starting to move up the stem of the main tiller and so this particular crop has just left growth stage 30.
“Within the next week, the crop will be at GS31, when the first node is 1cm off the base of plant, which marks the all-important T1 timing.”
Forward crops of barley, with dense canopies, were carrying quite high levels of disease, predominantly rhynchosporium and powdery mildew, which could be found readily. Mr Gate advised a prothioconazole-triazole fungicide mix to provide a combination of protectant and eradicant activity, alongside a PGR at the T1 timing.
“It may be a good idea at this stage to do some leaf tissue analysis to test the micronutrient levels within the leaf in order to address any deficiencies in the T1 spray,” he added.