Hot water treatment: an effective method for disinfecting Castanea sativa mill. dormant scions against Dryocosmus kuriphilus Yasumatsu.

Background: The Asian chestnut gall wasp (ACGW) Dryocosmus kuriphilus Yasumatsu is the most severe pest of the genus Castanea worldwide. After its arrival in Europe, the insect dispersed rapidly from Italy to other European countries, as well as spreading over long distances within each country because of the unintentional transport of infested chestnut material owing to the fact that infestation inside the dormant buds is visually undetectable. Hot water treatment (HWT) has been tested in terms of pest and diseases control in propagation processes with a wide range of plant material and species, including the Asian chestnut Castanea mollissima cv 'Qing'. Taking into account the different thermal tolerances of plant species, an experiment to disinfect Castanea sativa scions from ACGW by HWT was performed. The effects of the immersion of dormant scions for 10 min at two water temperatures (49 and 52 °C), with and without a previous period of water hydration, were tested.

Results: A 10 min soak at 49 °C was effective in killing ACGW larvae while retaining an excellent percentage of successful grafts. The pre-HWT hydration stage did not influence the success of the treatment. Positive shoot growth was also recorded after HWT.

Conclusions: We report for the first time the effectiveness of a simple and environmentally friendly protocol based on hot water for the disinfection of European chestnut (C. sativa) scions against D. kuriphilus. This will enable nurseries to supply plants free from this pest, preventing the insect dispersion, which will have a positive socio-economic impact to the chestnut tree sector. Also positive environmental impact will be favoured as gall wasp proliferation will decrease. © 2019 Society of Chemical Industry.