Weed control in spring linseed: effects of knotgrass, chickweed, fat hen and oats on yield

Abstract

Linseed is a poor competitor with weed plants, so it is important to determine the influence of weed populations on the subsequent performance of linseed.

Four weeds were studied at different plant populations to determine the relative importance of different weeds, and the reduction in linseed yield that weed populations could cause if left uncontrolled.

The four weed species considered were:
Knotgrass (Polygonum aviculare)
Chickweed (Stellaria media)
Fat-hen (Chenopodium album)
Cultivated oats (Avena sativa)

The main conclusions were:
- grass weeds are likely to be more damaging to linseed than broad-leaved weeds
- knotgrass is potentially more competitive than fat-hen, and common chickweed is least damaging of the three studied weeds
- bearing in mind the cost of treatment, it would be economic to treat infestations greater than 14 oat, 5 knotgrass, 6 fat-hen and 40 chickweed plants/m², in vigorous linseed crops.

These experiments were conducted in three dry summers, two being extremely dry, and so it is possible that weed competition would have been greater in years where moisture was less limiting. Both chickweed and fat-hen were more adversely affected by the moisture stress than the linseed.