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Branch out for more OSR pods

Agronomy Issues
Georgina Wood OSR

Oilseed rape crops are poised for growth, as soon as soil temperatures warm up. Having been held in check by cold conditions and wet soils in recent weeks, the strong potential set down in the autumn is now likely to see rapid recovery in spring.

Using a PGR to suppress main stem dominance and to encourage side shooting could prove highly beneficial this season, believes Syngenta Technical Manager, Georgina Wood (above).

“Increased branching allows side shoots to develop along with the main stem, producing a better canopy structure and help to ensure crops reach the target 3.5 GAI at flowering,” she advised.

“That will maximise potential for more seed-bearing pods.”

OSR poised for spring growth

As day length now increases, oilseed rape plants will be triggered to grow away faster as soon as temperatures start to rise. “Earlier timing of PGR application, at the onset of stem extension, will have the greatest impact in reducing height and lodging risk,” she advocated, “particularly on hybrid or tall weak-stemmed varieties that will benefit most from Toprex application on actively growing crops.”

However, Miss Wood highlighted that the later timing for Toprex or Circle applications, targeted at the early to late green bud stage, would beneficially influence canopy architecture and flowering patterns, as well as reducing final height.

Not only does more consistent managed crop growth give potential to build green leaf area, but the synchronisation of flowering on both the main stem and branches into a short, intense period helps to reduce light reflectance and optimize energy capture for photosynthesis, she explained.

Open OSR canopy to let in light

Syngenta trials had shown that PGR treated plants had an average three to eight extra branches at harvest, compared to untreated. The greater number of secondary branches produced an additional 400 kg/ha yield. Branching is important to fulfill the post flowering determination of seed number and subsequent seed size. 

“Growers and agronomists can utilise the flexibility of PGR timing to tailor treatments to specific crops’ growth, with the potential to achieve more consistent results.”

Toprex contains the PGR, paclobutrazol, in combination with difenconazole fungicide, whilst Circle contains the PGR trinexapac-ethyl, which can be used in conjunction with a spring fungicide programme.