Healthy potential for remaining OSR

Hybrid vigour

FOR Cambridgeshire grower, Ian Lutey the demand for stronger growing plants has seen a switch to growing all hybrid varieties.

“We used to grow a mix of conventionals and hybrids, with the latter on more difficult or later sites,” he said.

“Now we look for hybrid vigour initially for establishment, but more importantly in spring to get crops away and build a good structure canopy, in part to outgrow CSFB effects.”

Emphasis

When selecting varieties, he now puts as much emphasis on the growth habit and health of the variety, including rooting vigour, as he does the yield figures from the Recommended List.

Larvae count

SYNGENTA technical manager Georgina Wood explained an ingenious and simple technique to assess CSFB larvae numbers, which would help growers calculate the potential impact on yield from different levels of infestation.

“Lay a sample of plants on chicken wire suspended above a plastic box with 50mm of water in the bottom, ideally in a greenhouse or somewhere light and dry,” she suggested.

Numbers

“The larvae think the plant is going into natural senescence and drop out, as if falling to the ground to pupate, only they fall into the water and drown.”

The water can be drained through a sieve and the larvae numbers easily counted.

“It has also been evident from the significant variation in larvae sizes collected, just how prolonged the infestation pressure went on for this season,” she said.

Benchmark success

MARGINAL gains from small tweaks at every stage of the OSR management could see a step change in yields and profitability, if growers can move closer to the crops’ yield potential, according to Sarah Kendall of ADAS.

It has been calculated that OSR has the capability to intercept 70% of available sunlight, which could generate the yield potential of 12 tonnes per hectare.

“Agronomic techniques, such as reduced reflectance of light by flowers and prolonging the green canopy for longer can all move the plant towards maximum performance,” she advised.

“But we also need to look at all the other factors to understand what is limiting a crop’s potential in any situation, such as root development, fertility or moisture availability.”