What's eating my sweet chestnut 'bouche de bétizac'?

Bouche de Bétizac is strongly resistant to oriental chestnut gall wasp via a hypersensitive reaction that kills gall wasp larvae at first instar. However, it still faces chestnut blight, grey squirrels raiding the crop, and deer browsing on young trees and fallen nuts — all common threats to Castanea in the UK and Europe.

Strip husks and take nuts from the tree before harvest; bark stripping on young stems can cause dieback. Use tree guards on young trunks. Net individual trees at ripening if practical. Trapping under licence where numbers are very high (UK regulations apply).

Orange-brown cankers on bark causing branch dieback; infected bark sinks and cracks; bark may fan out below the canker. Prune out and burn infected branches well below the canker. There is no cure; resistance breeding and biocontrol with hypovirulent strains are the long-term approaches.

Bouche de Bétizac shows near-complete resistance but may develop very occasional small galls that abort. In susceptible nearby trees, galls on buds and leaves weaken the tree. This cultivar's hypersensitive response provides natural control. Monitor nearby susceptible chestnut trees; the biocontrol wasp Torymus sinensis has been released in the UK.

Browsing of young shoots and bark stripping on saplings; fallen nuts consumed at harvest time. Fit tree shelters or deer guards (1.2 m minimum) on young trees. Fencing the plot is the most effective solution where deer pressure is high.