Aphids are still the most serious pests of cereals

Aphids continue to be the most serious pests of cereal crops in Ireland. The issues caused by the pests were discussed in detail across two presentations at the National Tillage Conference today.

Tom Kennedy, retired Teagasc, Research Entomologist spoke on aphid control in cereals and Steve Foster of Rothamsted Research in the UK outlined the issue of aphicide resistance in grain aphids.

Kennedy highlighted to the large attendance that aphids damage crops in two ways. Firstly by transmitting virus disease BYDV to and within crops and secondly by direct feeding on tillers.

He highlighted: “Research in Oak Park found yield reductions due to virus disease as high as 3.7t/ha in winter barley and almost 2t/ha in late April sown barley.” He noted that significant reductions are also evident in from aphid feeding on winter wheat and late April sown barley.

Kennedy outlined recommendations for the control of aphids based on the results of research at Oak Park. He said: “Early September sown barley should be sprayed with aphicide at the 2-3 leaf stage and again in early November. Crops sown in late September need only a single aphicide application in early November.”

He continued: “In general, cereal crops sown in the first week of November and before the middle of March have no requirement for aphicide treatment even in bad seasons.

Kennedy noted: “The most damaging aphid species affecting cereals in Ireland is the grain aphid. The most effective means of controlling this pest has been the application of properly timed pyrethroid type insecticides.”

However recent research in the UK has confirmed the development of resistance to pyrethroid insecticides in the grain aphid. Steve Foster who took part in the research noted: “Of the thousands of aphid species that exist globally, only very few have been reported as having developed insecticide resistance. ”

He commented: “Until recently, the only species found on field crops to carry pyrethroid resistance was the peach potato aphid. However in response to growing concerns that the grain aphid was becoming harder to control in England research was carried out in 2011.”

Results indicated that high levels of BYDV virus found in cereal crops across England may in part be caused by pyrethroid resistant aphids.

Kennedy noted: “ This development is particularly concerning because there are only a limited number of alternatives to pyrethroids for aphid control.” He noted of the 30 insecticide products registered for aphid control, 17 are pyrethroids.

Pictured: Harvesting winter barley. Photo O’Gorman Photography

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