Weed and arthropod populations in conventional and genetically modified herbicide tolerant fodder beet fields

Published source details Strandberg B., Bruus Pederson M. & Elmegaard N. (2005) Weed and arthropod populations in conventional and genetically modified herbicide tolerant fodder beet fields. Agriculture, Ecosystems & Environment, 243-253.
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This study is summarised as evidence for the following.

	Action	Category
	Delay herbicide use Action Link

Delay herbicide use

A randomised, replicated, controlled study in 2001 on Mors, Denmark (Strandberg et al. 2005, the same study as Strandberg & Bruus Pederson 2002) found more arthropods (including insects and spiders) in July in plots receiving late herbicide applications (averaging approximately 525 arthropods/m²) compared to plots receiving herbicide at recommended (290 arthropods) or early (230 arthropods) spraying dates. The diversity of arthropod groups and species in July was also higher in plots treated late (20 groups/0.9 m²) rather than at recommended (16 groups) or early (12 groups) spraying dates. This study did not distinguish between pest and natural enemy arthropods and aphids (Aphidoidea), thrips (Thysanoptera), mites (Acari) and springtails (Collembola) were not included. More weeds occurred in mid-May to mid-August in plots sprayed late (2-89 g weed dry weight/m²) than in plots sprayed at recommended (2-10 g dry weight) or early (2 g dry weight) dates. The experiment took place in 20 x 20 m plots of beet Beta vulgaris. Glyphosate herbicide (roundup ready) was sprayed in three timing treatments: early (25 May and again 27 June), recommended (14 June and 5 July) and late (27 June and 16 July) applications. Treatments were replicated four times. Arthropods were sampled with a Dietrick vacuum sampler.