- Forecasts risk of Barley Yellow Dwarf Viruses
- System is simple but very effective
- Helps to reduce insecticide usage
Farmer-led aphid monitoring could help reduce the use of insecticides to tackle barley yellow dwarf virus (BYDV) in cereals.
A simple field-based monitoring system – run by farmers – could help combat BYDV following the 2019 neonicotinoid ban, according to the study by the Game & Wildlife Conservation Trust (GWCT).
A potentially devastating disease, BYDV can reduce yields by 30% in wheat and 75% in barley. Yields are most affected by autumn infestations of virus carrying aphids flying into cereal crops.
Pyrethroid insecticides used as an alternative to neonicotinoids are toxic to the beneficial insects in the crop. They also have the potential to contaminate waterways where they are highly toxic to aquatic insects.
Funded by the Agriculture and Horticulture Development Board (AHDB), the study shows that field-based monitoring to count aphid numbers can predict the risk of BYDV transmitted by cereal aphids in the autumn.
It also showed that better understanding of aphid infestations improves both the targeting and the timing of insecticide applications. This reduces spray usage because aphids are controlled before they have a chance to spread within the crop.
Researchers tested the practicality of field-based monitoring by equipping seven farmers and agronomists with yellow sticky traps – 20cm² cards coated with wet-stick mounted horizontally just above the crop.
Yellow is known to be attractive to aphids. The farmers and agronomists were asked to trial the traps for a month, changing them every week. They were given a simple guide to assess aphid numbers.
John Holland, head of the GWCT’s farmland ecology unit, said: “The participants liked the simplicity of the approach and would be willing to use it, but wanted better training in aphid identification in future.”
Traps were deployed in the headlands and middle of different fields so researchers could examine whether landscape composition, boundary type and tillage methods affect aphid immigration into crops.
“We found at least three times as many flying aphids in the headland area compared with the field centre in both studies, and especially next to tall boundaries, indicating that wind currents determined aphid immigration patterns within fields.”
The scientists found that the type of tillage had no impact on levels of aphid immigration. By studying a range of landscapes, they found more aphids where there was a higher proportion of grassland with a 1km radius of the sampled field.
“We found considerable variation in aphid numbers between fields (24% had none), even on the same farm, which confirms the merits of field-based monitoring to reduce insecticide use.”