Hot, dry weather has seen a rapid increase in the aphid numbers in potato fields and a high-risk species has been identified in a Maris Piper crop in south Lincolnshire.

With temperatures predicted to reach 30C in parts of eastern England, growers must inspect crops for the aphid migrations and be prepared to take action in vulnerable crops, said Stephen Williams, Syngenta’s potato technical manager.

“After the late planting and slow start to spring, many seed crops are still at early tuber initiation stage, when they are most susceptible to virus transmission by feeding activity of infected aphids. Growers with ware crop varieties susceptible to virus should adopt the same strategies,” he added.

While Myzus persicae (peach potato aphid) was the greatest threat for transmitting potato viruses, it presented the most difficult control challenges, said Mr Williams. Other aphid species can also spread infection and may be present in far higher numbers, which would impact on yields.

If winged aphids were seen on the crop, growers need to delve deep into the canopy and inspect a number of plants closely, to see if the aphids are isolated pests that have flown in, or have developed from existing colonies in the crop.

“Myzus colonies in particular are often present on the underside of lower leaves, which can be difficult to find.

“It also poses a real challenge for application to target aphids hidden deep in the crop. Angled sprays, using Syngenta’s potato nozzle, will help to get spray through the canopy. Revus and Shirlan blight applications will protect lower leaves and stems,” he added.

The latest information on the key aphid pest populations and migration can be obtained from the HDC Pest Bulletin, available free to all growers on the Syngenta website.