Maize is one of the world’s most widely grown crops and is often associated with one of its major insect pests, the European Corn Borer (Ostrinia nubilalis) This pest is of major economic importance in many parts of the world. It is native to western Asia and Europe and was most likely introduced to the United States in the twentieth century where it has become a major problem. Prior to the widespread planting of Bt maize in the US this insect was estimated to cost growers one billion dollars annually in yield and quality losses plus control costs. Equally, losses in Europe can be significant. In Germany, the yield losses due to Corn Borer in testcross hybrids amounted to 40%.
As well as the maize, other economically important crops can act as hosts; these include potatoes, oats, tomatoes, beans and celery amongst others.
With increased mean European temperatures and in particular warmer winters in the UK over the last decade, reports of this insect pest in Southern Britain have increased considerably. First reports started in the south west in 2011 and had spread as far as Kent and the M4 corridor by 2017.
DAMAGE:
European Corn Borers will feed on and injure almost any part of the maize plant except the roots. The larvae of the Corn Borer cause direct losses by boring into plant stems and ears in addition to indirect losses by facilitating the infection by micro-organisms such as Fusarium species. The major impact to the maize plant is loss of nutrient and water transfer to the grain, due to the tunneling or boring damage caused by the larvae in the stem. The tunnelling may also cause the tassels to drop before harvest, stems to snap, and allow secondary pathogens to attack the plant. As stems are weakened the risk of lodging increases which adds potentially further losses
UK DISTRIBUTION:
In theory the Corn Borer should not be a problem for UK growers as the climate is too cold for them to establish. However, there have been several reports where the damage is severe and therefore it appears that the pest has become established in the more southern parts of this country. In 2011 a farmer in south Devon reported damage from the European Corn Borer in his maize crop. Since then an increasing number of reports have been recorded in line with increases in temperatures. Increased temperatures typically lead to an increase in both growth and populations. More recently reports by members of the maize growers association indicate that in the summer of 2019 the Corn Borer, having gained a foot hold along the south coast of England, has started to move north presumably as a result of warming climate. Growers are reporting finds from as far afield as Kent and the south-west of England specifically along the M4 corridor. It would seem a reasonable assumption that as temperatures rise infestations are likely to increase in number and move further north and west into Wales in future years
FERA consider the risk of the Corn Borer establishing in the UK as very likely with a moderate pace. Growers are urged to report sightings to Fera. Opitma Excel can advise on possible control measures
both cultural and chemical
