Effect of the localized insecticides spray technique to control Halyomorpha halys in Actinidia chinensis orchards.

Kiwifruit production is rapidly expanding worldwide with China, New Zealand and Italy being the three major producing countries. Halyomorpha halys, the brown marmorated stink bug, is an invasive insect pest that in the last two decades has become a major problem for several agricultural commodities, including kiwifruit. Its management relies on integrating different control methods, including board-spectrum insecticides. Nevertheless, the chemical control may not achieve satisfactory results and there is still margin for improvement, considering for instance the optimization of the spray technique. This problem is even more relevant in kiwifruit due to its peculiar training system, which reduce fruit exposure to pesticide sprays. In this study, two spray techniques were tested to maximize the insecticides efficacy in controlling H. halys in both yellow- and green-flesh kiwifruit cultivars (‘Jintao’ and ‘Hayward’). The effects of a conventional ray atomizer and a trumpet-modified atomizer, which localizes insecticide applications in the fruit area, were assessed on H. halys mortality (with artificial infestations) and fruit damages (due to H. halys naturally occurring in the orchards). The localized spray technique resulted in an overall significantly higher H. halys mortality in ‘Hayward’, but not in ‘Jintao’ cultivar. This is likely due to the differences in the canopy size and structure of these cultivars, observed recording biometric parameters of the vines. However, the fruit injury level was not different between the spray techniques. Further investigations in this direction are needed also to assess the efficiency of the localized spray technique in reducing insecticide dose and volume, in accordance to European strategies for sustainable developments that foreseen a restriction of authorized insecticidal active substances and an overall reduction of plant protection products usage.