12 April 1996

No blueprints for linseed

By Andrew Blake

TALK of production blueprints for autumn-sown linseed are premature, say specialists.

Inferences made from the site at ADAS Bridgets (Arable, Mar 15) could be misleading, says ADASs Dr Jenny Smith. "The optimum sowing date may be different for different regions of the UK."

Minimum soil temperatures, at the end of December, at High Mowthorpe, Yorks, were -15.5C (4F) – much lower than the -7.5C (18.5F) experienced at Bridgets in Hampshire, she notes.

"At both sites, plants sown on or before Oct 12 survived the winter. A large proportion of the plants which were sown late in October and November died during the winter."

Plants from late September and early October drillings had the best growth habit to survive, suggesting this is the best time to sow. "However this needs to be verified in further work," says Dr Smith.

"We may well need different recommendations for the north and the south," says Chris Green of Semundo. He believes it is much too soon to be specific about optimum sowing dates.

The company is trialling Oliver alongside autumn-sown spring varieties at 12 sites from Aberdeen to Cornwall. Sowing dates at each site differ by 14 days from late September to early October. Four sowing rates, three levels of nitrogen, herbicides and growth regulators are also being evaluated.

"We have seen some differences in hardiness between the spring varieties. But none is hardy enough to be sold with any confidence as a winter variety." This season proved Oliver is genetically distinct from other types, he says.

Late March assessments of Semundo trials at Harlow Agricultural Merchants Herts site, where new year temperatures fell to -10C (14F), show severe winter kill of spring types. "In most cases this has proved terminal," says seeds manager Darrell Clark.

On a 0-9 scale, where 9 is dead, Oliver rated 0.5 against 9 for Antares, Barbara, Bolas and Mikael, all sown on Sep 21. The picture was little different in the Oct 5 sowings – Oliver rated nil, Bolas seven, the remaining three varieties 9.

Frosts caused the very forward spring types to snap midway along the stem, he explains. "Oliver suffered very little damage due to its prostrate growth habit."

Pigeons have been no problem, and he anticipates an end July/early August harvest – two to three weeks ahead of spring sown crops. &#42

&#8226 Too early for blueprints.

&#8226 Target sowing dates likely to vary around the country.

&#8226 Late Sept-early Oct looks best, but needs verifying.

&#8226 End July/early Aug harvest expected – 2-3 weeks early.

Optimum UK sowing dates for true winter linseeds are still unclear. But last winter showed that sowing spring types in the autumn is highly risky, say HAMs Darrell Clark and Semundos Fiona Davies.