Improvement of management guidelines for linseed

Abstract

This report summarises the research undertaken by ADAS. Four separate experiments were done during the 1991, 1992 and 1993 seasons at seven sites in England. These consisted of experiments examining methods of establishment (one site for two years), nitrogen requirements and plant growth regulators (seven sites for three years), fungicide programmes (three sites for three years) and harvesting techniques (one site for two years).

The work on establishment has demonstrated that linseed can be sown into a minimally cultivated seedbed that is cheaper to prepare than that traditionally made without a significant increase in seed rate. This work supports earlier work and the recommendation to include a factor for establishment when calculating seed rates. This has been incorporated into an advisory service for growers (ADAS Linseed Sowing Guide).

The experiment on crop nitrogen requirements has demonstrated that linseed will only respond to applied nitrogen if the site has low soil nitrogen reserves. Only five sites of the twenty-one showed a yield response up to 80 kg/ha N. There are therefore cost savings to be made and the crop excels as an environmentally benign addition to the arable rotation. This experiment also examined the role of the plant growth regulator chlormequat as an input for linseed. Whilst plant height and severity of lodging were reduced, yield increases were less predictable and were not always related to lodging. The experiment demonstrated that chlormequat increased capsule numbers per plant and thus potential yield. The yield increase obtained from the use of chlomequat did not cover its cost and therefore is not recommended as a cost effective input. Lodging remains a problem in linseed; the best defence is to grow it at lower populations (c. 350 plants/2).

The experiment on fungicide programmes showed that disease levels rose as nitrogen levels increased and that a two-spray fungicide programme was required for good control of the disease. Yield responses were not closely associated with a particular timing but yield increases in the order of 10-20% were obtainable from programmes containing either a mid- flowering or capsule formation spray making a single spray cost effective. The relative importance of Alternaria declined during the three-year period as weather conditions favoured powdery mildew and Botrytis to a greater extent.

Harvesting remains the greatest potential problem for producers of linseed. The experiment showed that there was no difference between the harvesting methods used. In dry conditions the use of a desiccant was unnecessary. However, in more typical, changeable conditions a desiccant whilst giving no yield benefit, reduces seed moisture and eases harvesting.

Overall savings of between £50/ha and £23/ha can be achieved by adopting these findings when comparing 1986 guidelines with those resulting from this work. This programme of research has been widely disseminated and its findings are already being utilised by linseed producers in England.