Aphids increase whilst predators lag behind

Following the cold winter relatively few aphids were seen in arable crops in early summer. However, recent trap results suggest that numbers are building and could pose a serious risk to autumn sowings.

The numbers of aphids flying in recent weeks are at similar levels to this time last year. The Brooms Barn aphid traps also record the number of ladybirds and these have not built up; at the moment they are at 25% of the level in 2009.

This could mean that the risk of turnip yellows (TuYV) in rape and BYDV in cereals this autumn might be higher than last year. This is particularly worrying as our and other surveys for TuYV in the current crop show that levels are high in many areas. Growers will need to use a good seed treatment to control TuYV and BYDV, advises Adrian Cottey, Seed Treatment Manager for Bayer CropScience. Clothianidin is a new generation neonicotinoid treatment that gives good control of establishment pests but, importantly, it also prevents aphids spreading these viruses. As Modesto in oilseed rape it is the only treatment with label approval for TuYV. As Redigo Deter it will control BYDV in cereals.

Recent work by Brooms Barn shows that TuYV is present in all plant parts, including the roots of infected rape. This is worrying as aphids feeding on regrowth in stubbles could pick up the virus and pass on to newly emerged rape this autumn. Obviously numbers of volunteers can be reduced by good stubble cultivations, but the risk of virus transfer from other sources including weeds and field margins, suggest that investment in clothianidin seed treatments will be well worthwhile this season, advises Mr Cottey.

About Bayer CropScience

Bayer is a global enterprise with core competencies in the fields of health care, nutrition and high-tech materials. Bayer CropScience AG, a subsidiary of Bayer AG with annual sales of about EUR 6.5 billion (2009), is one of the worlds leading innovative crop science companies in the areas of crop protection, non-agricultural pest control, seeds and traits. The company offers an outstanding range of products and extensive service backup for modern, sustainable agriculture and for non-agricultural applications. Bayer CropScience has a global workforce of 18,700 and is represented in more than 120 countries.