Winter linseed: i. comparison of winter and spring varieties ii. weed control trials

Abstract

i. Linseed variety trails were grown at three locations during the 1995-96 season to compare yield potential of winter and spring linseed. The effect of sowing date on the performance of spring linseed was also investigated.

In the 1995/96 season, the two commercially available winter hardy varieties, Arctica and Oliver, were grown in autumn-sown plots as controls. Their mean seed yield was 55% greater than the mean of the seven mid-March sown spring linseed varieties in spring trials and 78% greater than their mid-April sown mean yield. A general trend for improved oil content from autumn sowing was seen. Spring linseed varieties, sown in the autumn, showed a clear susceptibility to winter damage and gave very low yields, or failed to survive at all.

The same winter varieties, grown in spring, showed only moderate yield. It was concluded that the greater yield obtained from the autumn plots was the result of more effective exploitation of soil moisture, rather than variety performance as such.

A strong effect of sowing date on seed yield in spring-sown linseed was noted in these experiments. Early-sown plots gave higher yields than later down plots by an average of 15% but these improvements were small compared with the advantage shown by the winter linseeds sown in autumn. It was concluded that the advantage came from better utilisation of available soil moisture in a dry season. However, a considerable range of seedling vigour was observed which supported earlier experience, and breeder's advice, that establishment may be more reliable if delayed until early April, especially for small-seeded varieties, given adequate moisture.

The winter linseed trails came to harvest 2-4 weeks earlier than those of spring-sown linseed. For spring-sown linseed, no maturity advantage was gained from early sowing.

ii. Winter linseed is now commercially available in the UK. It has many advantages over spring linseed which make it more attractive to growers, these being its early maturity, its higher yield potential and it is less susceptible to attack from the flax flea beetle.

A one-year investigation, from October 1995 to August 1996, at ADAS Boxworth, Cambridge evaluated a number of pre-emergence and post-emergence herbicides, at set timings, to winter linseed to determine their  performance on seed quality and yield. Herbicides included trifluralin, linuron, metazachlor, metsulfuron-methyl, bentazone, bromoxynil plus ioxynil plus clopyralid. The objectives were to evaluate broad-leaved weed control programmes for winter linseed in terms of their efficacy and crop safety. This encompassed both autumn and spring weed control programmes in comparison with untreated controls.

Linseed plant populations were decreased by pre-emergence applications of metazachlor Amidosulfuron was most effective spring applied herbicide on cleavers and when in combination with metsulfuron-methyl, as a tank-mix or a sequence, chickweed was also controlled.

At the time of writing (February 1997) amidosulfuron is not approved for use in winter linseed. Data has been submitted by the chemical company towards full label approval of the product for spring application, but it is unlikely to be available for spring 1997. This study has shown that there are no alternatives that provide the degree of control of cleavers shown by amidosulfuron. There was no effect of post-emergence herbicides on yield of seed. Gross margins were decreased by between £11 and £100 by herbicide treatment.