Italian defence against the cynip threat in the Dordogne

THERE was an air of confidence from Italian chestnut producers who have beaten a cynip insect infestation of their crop, as they explained how during a conference on the future of the industry in the Dordogne.

Renzo Panzacchi had come from Bologna to speak at the Printemps de la Châtaigne industry exhibition held in Mazeyrolles, that looked at ways to expand and support the chestnut sector.

He spent around 20 minutes explaining how their own region’s chestnut producers had faced the threat of the cynip, a small wasp-like insect, that was slowly killing the trees and causing great distress amongst 100 or so farms.

The chestnut growers of Bologne were made up of many small farms, but it was still an industry that brought around €2,500,000 to the area each year, and so it was decided to fight back against the cynip, and they looked to Asia for a solution.

The original cynip infestation was traced to imports of horticultural material from China, and further study showed that the problem had been dealt with in Japan in the 1980s.

This was achieved through the introduction of another insect, the Torymus sinensis, which feeds on the cynip whilst in galls found on the chestnut and when properly managed can eventually reduced the damage to the trees.

The small red and green galls can be seen forming on this chestnut tree in Loubéjac.

And that damage can be severe as Renzo Panzacchi described seeing 25 galls spread along just 20 cm of chestnut tree branch. While a producer in France explained earlier in the morning how his own production was reduced by more than half, despite doubling the number of hectares under production.

Renzo Panzacchi continued and said that working with university and ministry of agriculture researchers the local producers began to introduce the Torymus sinensis after setting up a system across the region that slowly saw their presence spread naturally.

After five years the patience and determination of the Bologna chestnut farmers was rewarded as they saw the cynip population decline, yet retained a balance with the Torymus sinensis, and saw their production levels back to around 95% of what they were before the arrival of the cynip.

The cynip can be beaten, Renzo Panzacchi said, without turning to chemicals and if the industry works as one.

See the full presentation from Renzo Panzacchi below (click on the slides to advance).