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Chestnut Tree Disease Now Under Control

Chestnut growers have been under a lot of strain in Curral das Freiras as trees have been affected by the chestnut gall wasp known as Dryocosmus Kuriphilus Yasumatsu.  The wasp was first identified on the island in 2014 in the main chestnut growing areas of Curral das Freiras, Câmara de Lobos and Ribeira Brava.

This year, Madeira’s 500 chestnut growers will harvest an estimated total of 114 tonnes. However, although the Regional Secretary for Agriculture said that the pest is now under control, they have blamed the hot weather for this year’s reduced yield.

Originating in China, the  Dryocosmus Kuriphilus Yasumatsu was first identified in Japan in 1951, and is considered one of the worst chestnut tree pests in the world.  The female wasp lays about 100 eggs in dormant chestnut tree buds.  These remain dormant until the spring. Growing as the tree buds develop the larvae induce the formation of green or pinkish galls on the tree which can be up to 2 cm in size.  The larvae continue to grow within the gall and finally emerge as adults; this, in turn, makes the tree vulnerable as they not only disrupt growth, reduce an individual’s trees yield by 70%.  They further increase the likelihood of a tree becoming infected with the chestnut blight (Cryphonectria parasitica) and the sweet chestnut pathogen (Gnomoniopsis smithogilvyi).   

Samantha Gannon

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Photo: Ricardo Gomez Angel

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