Turnip Yellows Virus (TuYV), carried by the peach-potato aphid (Mysus persicae), can affect up to 100%1 of oilseed rape (OSR) crops, reducing yield by as much as 30%2. Up to 72%3 of peach-potato aphids carry the disease, which means that a small number of infected aphids can have a major impact on vulnerable young OSR plants during establishment, making the identification of this aphid vital in order to protect crops. The aphids are usually found on the underside of leaves and in large numbers can also cause damage through feeding on leaves.
The diagrams below outline the key features of the peach-potato aphid and its life cycle. For support on how to identify aphids, see our blog here.
Peach potato aphids are likely to move into new oilseed rape crops from host crops such as sugar beet, vegetable brassicas and potato crops, as these are commonly still in the ground in September.
Unfortunately, the peach-potato aphid is resistant to pyrethroids, which were previously effective in controlling the virus. Growers, therefore, need to look for alternative methods to minimise yield reduction through TuYV.
Here are five tips to stop TuYV in its tracks:
1. Choose your variety carefully. There are a number of seed options available now, both hybrid and conventional, that are TuYV resistant.
2. Growing wildflower strips with a diverse grass mixture will encourage parasitoids and hoverflies that prey on aphids. Typically, these would be situated around the edges of fields, but trials by the Centre for Ecology and Hydrology are seeking to establish whether running strips of wildflowers through crops at intervals will bring even better results.
3. Get into the habit of checking the AHDB’s weekly Aphid News bulletins. The newsletters will keep you up to date with the prevalence of the peach-potato aphid, and other aphids, in your area, as well as giving advice on effective controls. The bulletins’ data is based on the numbers of aphids caught in suction traps at various sites across the UK and allows quick comparison with previous years.
4. Don’t forget to walk the crops to look for infestations in the autumn, particularly if AHDB traps in your area catch peach-potato aphids. The peach-potato aphids themselves come in winged and wingless varieties. Both varieties are 1-2mm in length and oval shaped. The wingless aphids can vary considerably in colour from several shades of green to yellow, pink, red and almost black. The winged aphids have a black central patch on their upper surface with a clear window at one end. The underside of their abdomens are completely pale.
5. Consider using a chemical application, if peach-potato aphids are present. Biscaya (thiacloprid) is a fast-acting systemic insecticide, which can save you £30/ha by controlling peach-potato aphids. Remember, no more than two foliar applications of any type of neonicotinoid spray should be used in any one year, to reduce the chance of aphid resistance building up.
Biscaya is a systemic insecticide that provides you with control of aphids in your oilseed rape crop
You can check your OSR leaves for light leaf spot for free thanks to SpotCheck, a collaboration between Bayer and ADAS with extensive support from the Association of Independent Crop Consultants (AICC).