April 2, 2014
Pushing for yield from a strong platform
Our hybrid winter rape crops have developed especially well this spring, reports Midlands agronomist, Harry Abell. Relatively cool conditions have taken the froth off the early growth so they’ve gone into April moving from green to yellow bud – and into early flowering in some cases – with GAIs of around 2.5-3.0, having only had around 50 kg/ha of early nitrogen. What’s more, they’re nice and chunky, with solid root systems and great branching for maximum potential.
The speed with which DK Expower, DK Excellium and Excalibur, in particular, have grown away has been really valuable in out-competing large numbers of pure line volunteers in a number of cases. Overall, we’re looking at populations of 30 plants/m2 from sowings of 35-40 seeds/m2 with plenty of canopy promise.
Seeing how well the crops were developing from the autumn, we were able to separate our nitrogen from sulphur in fertiliser purchasing wherever possible. This allowed us to go on with poly-sulphate or kieserite to deliver the S as soon as we could travel in February, holding back the first N until early March to avoid excessive vegetative growth. The scavenging ability of the varieties we’re growing and warmer soils than usual coupled with applications of poultry muck before sowing or 30 kg N in the seedbed means they never looked hungry.
Having got all the N we need for our canopies, we’re continuing to hold off on further applications for as long as we can to really push for yield, targeting a good 5t/ha this season. Where we’re still on solids, we’ll almost certainly have to put the remaining 100kg/ha on by mid-April. But extra flexibility where we’re using liquids means we’ll probably be going in with half at this stage and the other half in early May for the greatest pod boost.
Generally low phoma pressure and excellent RLM 7 resistance in most of our varieties has meant we’ve had few problems from the disease this season – with the exception of one susceptible crop that was filthy with infection. Despite the season, it’s almost certain to suffer significant losses from the late stem infections we so often see and many people seem to mistake for verticillium.
We tackled light leaf spot infections coming into a number of crops with a late February dose of Kestrel (prothioconazole + tebuconazole), adding an early trace element mix. In the past week we’ve gone in with a good rate of Juventus (metconazole) at green bud for growth regulation, adding trace elements to the crops that didn’t get them earlier. After all, it’s a long way to harvest and we could easily get the sort of torrentially wet conditions that caused so much root lodging pressure two years back.
Fingers crossed, pollen beetles have continued to be notable for their scarcity. So we may get away without any extra insecticide this spring. But with crops already moving into flowering, we’re gearing-up for a well-timed spray of PrioriXtra (azoxystrobin + cyproconazole) in the near future. This will give us some useful extra growth regulation too, as well as the opportunity for a micro-nutrient top-up to avoid any yield limitation.
Like many, I suspect, clethodim damage to some crops has been causing us concern. The product has done a great job on our black-grass but only time will tell the impact the worrying hormone-like distortion of flower buds may have on yields. We seen major differences in damage levels between varieties, though. And, thankfully, the Dekalb hybrids we’re mainly growing seem to be some of the least affected.