Colorado beetle is one of the worst potato pests but not, however, established permanently in Finland. The first Colorado beetles for this summer have been detected in Etelä-Savo and Uusimaa provinces.
The Finnish Food Safety Authority Evira was on Tuesday 19 June informed of a new colony of Colorado beetles in Kangasniemi in Etelä-Savo. A few adult beetles were found in Pornainen in Uusimaa on Wednesday 20 June. It is now vitally important that commercial potato farmers as well as home farmers monitor and inspect their fields regularly and report the sightings, if any, to Evira.
A home farmer in Kangasniemi detected dozens of adult beetles and clusters of eggs in different parts of his field. Due to the abundance of the beetles and the time of the year, it must have been a beetle from last summer whose new genration adults have overwintered in the ground and are now returning to the plants.
While inspecting an infestation site from last summer in Pornainen, the inspector detected a couple of adult beetles on potato plants which had been planted at the site of last year’s colony.
The beetles have now been destroyed at both the locations.
Colorado beetles were detected in 38 locations last summer. It is quite likely that every single beetle was not found and destroyed last summer and, consequently, new genration adults have survived the winter in the ground and are now emerging to feed on potato leaves and to reproduce. New beetles may also arrive in Finland, carried by heavy winds.
What to do when detecting a Colorado beetle?
Evira urges everyone who believes to have seen a Colorado beetle to immediately contact Evira and phone the hotline for sightings of Colorado beetles. Evira will then provide instructions for further measures, if needed. Inspectors at Economic Development, Transport and the Environment Centres (ELY-Centres) answer for the inspections and eradication of Colorado beetles. Farmers are urged not to start destroying the beetles on their own because it will complicate the eradication measures taken by the authorities. The link below gives instructions for monitoring and measures when detecting beetles.
At this time of the year, one can find both adult beetles and eggs on potato plants, and soon also larvae. An adult beetle is about one centrimetre long and has ten black longitudinal stripes on its yellow back. Its yellow-orange eggs, about the size of a semolina grain, appear in compact masses on the underside of potato leaves.
Newly hatched larvae are about 1-2 millimetres long and darkish in colour. They grow fast and their arched backs soon turn orange-reddish. Below, on both sides of their thorax run two rows of black spots. A full-grown larva is a little over one centrimetre long.
At first, adult beetles and larvae eat up holes in potato leaves. The worst danger comes from the larvae which, in large populations, eat up nearly all the foliage. The potato plants which have lost their leaves form spots that are easy to distinguish from other plants.
The hotline for reporting the sightings: 040 801 4407 (preferably 10-18 hrs, also in the weekends).
Further information and photos of Colorado beetles:
www.evira.fi/koloradonkuoriainen (in Finnish)
Evira.fi > Plants > Cultivation and Production > Plant pests and diseases > Quarantine pests and diseases
Raija Valtonen, Head of Section, Evira, tel. +358 40 560 2510
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