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

Simple Summary Potassium bicarbonate is a mineral salt used as a fungicide on different crops, such as pears. Recently, it has also appeared to have some insecticidal activity against arthropod pests. Pear orchards are usually infested by Cacopsylla pyri that cause serious losses. Chemical pesticides (such as spirotetramat) are still cornerstone methods to control this pest, but are soon to require substitution by more environment-friendly products. For this reason, we tested the effects of potassium bicarbonate, with or without an adjuvant, as compared to spirotetramat, on the reduction of C. pyri juvenile forms in two field trials. The higher rate tested (7 kg ha(-1)) appeared more active on the pest and did not show any phytotoxic effects on pear plants. Potassium bicarbonate could, therefore, represent a viable product in the control of pear psylla and it might be usable in integrated management strategies focused on other plant pathogens, such as Stemphylium vesicarium. 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.

Automated summary

Potassium bicarbonate has been found to effectively control the number of pear psyllids without causing any phytotoxic effects on pear plants. It can be considered as a viable integrated pest management tool for controlling this pest.