Colorado Potato Beetle larvae found in Parikkala

20.7.2007

<div>The first Colorado potato beetle larvae have been discovered in Parikkala. Larvae of the beetle were found in a potato field as a consequence of the grower contacting Evira’s inspector. Inspectors went to study the finding and destroyed the larvae that were found. New findings are expected in the weeks to come, as the larval stage of the beetle has now begun. There is reason to monitor the potato plantings, especially on the south coast and on the eastern border</div>

On Tuesday a couple of dozen about one week old larvae were found within an area of a few square metres in a potato planting in Parikkala. Potatoes had not been grown in that spot last year, so it would seem that the beetle had apparently spread from an area nearby, probably from the other side of the eastern border at the end of June/beginning of July. No adult beetles were found. The finding is in the same area as the four findings in Parikkala and Kesälahti in 2006. In Sipoo, where the first finding for the summer were discovered, larvae have been found in addition to the adults and egg masses that had been found previously. All of the adult beetles that were found and their eggs and larvae have been destroyed.

Thanks to the fast action by the growers, the beetles have been brought under control on time and it has been possible to destroy the beetles. If a beetle colony goes undetected, the number of beetles can grow into 200-300 beetles during the first summer and the following summer there can be several thousand. This number of beetles is sufficient to destroy potato plantings of about one hectare if no control is undertaken.

All potato growers, including those with small potato plots should now check the potato plantings for larvae of the beetles, as the larval stage of the beetle is usually timed for the end of July/beginning of August. It is more likely that groups of larvae will be found than individual beetles. Evira is urging all potato growers to check the potato plantings regularly every week, especially in the coastal areas between Turku and Porvoo and in the southeast in the area between Lappeenranta and Joensuu. Individual beetles may have spread into these areas with the east-south-easterly air flows from Russia and the Baltic countries. The plant protection inspectors will be monitoring the potato plantings until the end of August.

Finding the beetles requires precision, especially in large potato fields and in high vegetation. Damage caused by potato late blight can also make it more difficult to find a colony.  The search is made easier by the following: The larvae always exist in groups or colonies, the colony usually covers a couple of square metres and at the initial stage the potato leaves are eaten so that they get holes and are shredded, at the final stage there may be only the leaf stalks left.

Any findings or sightings of Colorado potato beetles have to be reported immediately to the agricultural department of the local TE Centre or to Evira’s plant protection unit.

For more information, please contact:
Senior Inspector Olli Elfving, tel. +358 20 77 25048
Deputy Director Raija Valtonen tel. +358 20 77 25040

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