Efficacy and Selectivity of Potassium Bicarbonate Salts against Cacopsylla pyri on Pears

In recent years, the control of pear psyllid in northern Italy has not been particularly problematic, due to the presence of two insecticides (abamectin and spirotetramat) specifically for this pest, and due to the adoption of integrated pest management. However, the withdrawal of these two specific insecticides is imminent and, therefore, it has become necessary to find alternative control tools. More recently, potassium bicarbonate, known for its fungistatic activity against many phytopathogenic fungi, has also shown some activity against some insect pests. In the present study, the efficacy and possible phytotoxicity of potassium bicarbonate were tested in two field trials on second generation Cacopsylla pyri by spraying two different salt concentrations (5 and 7 kg ha^-1), with or without polyethylene glycol as an adjuvant. Spirotetramat was used as a commercial reference. The results showed that potassium bicarbonate could positively control the number of juvenile forms (with a mortality percentage of up to 89% at the infestation peak), even though spirotetramat was still more effective. Therefore, potassium bicarbonate appears to be a sustainable integrated tool for psyllid control, especially in the wake of the imminent withdrawal of spirotetramat and other insecticides currently used on this pest.